1 /*
2  * Copyright © 2014 Red Hat
3  *
4  * Permission to use, copy, modify, distribute, and sell this software and its
5  * documentation for any purpose is hereby granted without fee, provided that
6  * the above copyright notice appear in all copies and that both that copyright
7  * notice and this permission notice appear in supporting documentation, and
8  * that the name of the copyright holders not be used in advertising or
9  * publicity pertaining to distribution of the software without specific,
10  * written prior permission.  The copyright holders make no representations
11  * about the suitability of this software for any purpose.  It is provided "as
12  * is" without express or implied warranty.
13  *
14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
20  * OF THIS SOFTWARE.
21  */
22 
23 #include <linux/bitfield.h>
24 #include <linux/delay.h>
25 #include <linux/errno.h>
26 #include <linux/i2c.h>
27 #include <linux/init.h>
28 #include <linux/kernel.h>
29 #include <linux/random.h>
30 #include <linux/sched.h>
31 #include <linux/seq_file.h>
32 #include <linux/iopoll.h>
33 
34 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
35 #include <linux/stacktrace.h>
36 #include <linux/sort.h>
37 #include <linux/timekeeping.h>
38 #include <linux/math64.h>
39 #endif
40 
41 #include <drm/display/drm_dp_mst_helper.h>
42 #include <drm/drm_atomic.h>
43 #include <drm/drm_atomic_helper.h>
44 #include <drm/drm_drv.h>
45 #include <drm/drm_edid.h>
46 #include <drm/drm_print.h>
47 #include <drm/drm_probe_helper.h>
48 
49 #include "drm_dp_helper_internal.h"
50 #include "drm_dp_mst_topology_internal.h"
51 
52 /**
53  * DOC: dp mst helper
54  *
55  * These functions contain parts of the DisplayPort 1.2a MultiStream Transport
56  * protocol. The helpers contain a topology manager and bandwidth manager.
57  * The helpers encapsulate the sending and received of sideband msgs.
58  */
59 struct drm_dp_pending_up_req {
60 	struct drm_dp_sideband_msg_hdr hdr;
61 	struct drm_dp_sideband_msg_req_body msg;
62 	struct list_head next;
63 };
64 
65 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
66 				  char *buf);
67 
68 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
69 
70 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
71 				     int id, u8 start_slot, u8 num_slots);
72 
73 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
74 				 struct drm_dp_mst_port *port,
75 				 int offset, int size, u8 *bytes);
76 static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
77 				  struct drm_dp_mst_port *port,
78 				  int offset, int size, u8 *bytes);
79 
80 static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
81 				    struct drm_dp_mst_branch *mstb);
82 
83 static void
84 drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
85 				   struct drm_dp_mst_branch *mstb);
86 
87 static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
88 					   struct drm_dp_mst_branch *mstb,
89 					   struct drm_dp_mst_port *port);
90 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
91 				 u8 *guid);
92 
93 static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port);
94 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port);
95 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
96 
97 static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
98 						 struct drm_dp_mst_branch *branch);
99 
100 #define DBG_PREFIX "[dp_mst]"
101 
102 #define DP_STR(x) [DP_ ## x] = #x
103 
104 static const char *drm_dp_mst_req_type_str(u8 req_type)
105 {
106 	static const char * const req_type_str[] = {
107 		DP_STR(GET_MSG_TRANSACTION_VERSION),
108 		DP_STR(LINK_ADDRESS),
109 		DP_STR(CONNECTION_STATUS_NOTIFY),
110 		DP_STR(ENUM_PATH_RESOURCES),
111 		DP_STR(ALLOCATE_PAYLOAD),
112 		DP_STR(QUERY_PAYLOAD),
113 		DP_STR(RESOURCE_STATUS_NOTIFY),
114 		DP_STR(CLEAR_PAYLOAD_ID_TABLE),
115 		DP_STR(REMOTE_DPCD_READ),
116 		DP_STR(REMOTE_DPCD_WRITE),
117 		DP_STR(REMOTE_I2C_READ),
118 		DP_STR(REMOTE_I2C_WRITE),
119 		DP_STR(POWER_UP_PHY),
120 		DP_STR(POWER_DOWN_PHY),
121 		DP_STR(SINK_EVENT_NOTIFY),
122 		DP_STR(QUERY_STREAM_ENC_STATUS),
123 	};
124 
125 	if (req_type >= ARRAY_SIZE(req_type_str) ||
126 	    !req_type_str[req_type])
127 		return "unknown";
128 
129 	return req_type_str[req_type];
130 }
131 
132 #undef DP_STR
133 #define DP_STR(x) [DP_NAK_ ## x] = #x
134 
135 static const char *drm_dp_mst_nak_reason_str(u8 nak_reason)
136 {
137 	static const char * const nak_reason_str[] = {
138 		DP_STR(WRITE_FAILURE),
139 		DP_STR(INVALID_READ),
140 		DP_STR(CRC_FAILURE),
141 		DP_STR(BAD_PARAM),
142 		DP_STR(DEFER),
143 		DP_STR(LINK_FAILURE),
144 		DP_STR(NO_RESOURCES),
145 		DP_STR(DPCD_FAIL),
146 		DP_STR(I2C_NAK),
147 		DP_STR(ALLOCATE_FAIL),
148 	};
149 
150 	if (nak_reason >= ARRAY_SIZE(nak_reason_str) ||
151 	    !nak_reason_str[nak_reason])
152 		return "unknown";
153 
154 	return nak_reason_str[nak_reason];
155 }
156 
157 #undef DP_STR
158 #define DP_STR(x) [DRM_DP_SIDEBAND_TX_ ## x] = #x
159 
160 static const char *drm_dp_mst_sideband_tx_state_str(int state)
161 {
162 	static const char * const sideband_reason_str[] = {
163 		DP_STR(QUEUED),
164 		DP_STR(START_SEND),
165 		DP_STR(SENT),
166 		DP_STR(RX),
167 		DP_STR(TIMEOUT),
168 	};
169 
170 	if (state >= ARRAY_SIZE(sideband_reason_str) ||
171 	    !sideband_reason_str[state])
172 		return "unknown";
173 
174 	return sideband_reason_str[state];
175 }
176 
177 static int
178 drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len)
179 {
180 	int i;
181 	u8 unpacked_rad[16];
182 
183 	for (i = 0; i < lct; i++) {
184 		if (i % 2)
185 			unpacked_rad[i] = rad[i / 2] >> 4;
186 		else
187 			unpacked_rad[i] = rad[i / 2] & BIT_MASK(4);
188 	}
189 
190 	/* TODO: Eventually add something to printk so we can format the rad
191 	 * like this: 1.2.3
192 	 */
193 	return snprintf(out, len, "%*phC", lct, unpacked_rad);
194 }
195 
196 /* sideband msg handling */
197 static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles)
198 {
199 	u8 bitmask = 0x80;
200 	u8 bitshift = 7;
201 	u8 array_index = 0;
202 	int number_of_bits = num_nibbles * 4;
203 	u8 remainder = 0;
204 
205 	while (number_of_bits != 0) {
206 		number_of_bits--;
207 		remainder <<= 1;
208 		remainder |= (data[array_index] & bitmask) >> bitshift;
209 		bitmask >>= 1;
210 		bitshift--;
211 		if (bitmask == 0) {
212 			bitmask = 0x80;
213 			bitshift = 7;
214 			array_index++;
215 		}
216 		if ((remainder & 0x10) == 0x10)
217 			remainder ^= 0x13;
218 	}
219 
220 	number_of_bits = 4;
221 	while (number_of_bits != 0) {
222 		number_of_bits--;
223 		remainder <<= 1;
224 		if ((remainder & 0x10) != 0)
225 			remainder ^= 0x13;
226 	}
227 
228 	return remainder;
229 }
230 
231 static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes)
232 {
233 	u8 bitmask = 0x80;
234 	u8 bitshift = 7;
235 	u8 array_index = 0;
236 	int number_of_bits = number_of_bytes * 8;
237 	u16 remainder = 0;
238 
239 	while (number_of_bits != 0) {
240 		number_of_bits--;
241 		remainder <<= 1;
242 		remainder |= (data[array_index] & bitmask) >> bitshift;
243 		bitmask >>= 1;
244 		bitshift--;
245 		if (bitmask == 0) {
246 			bitmask = 0x80;
247 			bitshift = 7;
248 			array_index++;
249 		}
250 		if ((remainder & 0x100) == 0x100)
251 			remainder ^= 0xd5;
252 	}
253 
254 	number_of_bits = 8;
255 	while (number_of_bits != 0) {
256 		number_of_bits--;
257 		remainder <<= 1;
258 		if ((remainder & 0x100) != 0)
259 			remainder ^= 0xd5;
260 	}
261 
262 	return remainder & 0xff;
263 }
264 static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr)
265 {
266 	u8 size = 3;
267 
268 	size += (hdr->lct / 2);
269 	return size;
270 }
271 
272 static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
273 					   u8 *buf, int *len)
274 {
275 	int idx = 0;
276 	int i;
277 	u8 crc4;
278 
279 	buf[idx++] = ((hdr->lct & 0xf) << 4) | (hdr->lcr & 0xf);
280 	for (i = 0; i < (hdr->lct / 2); i++)
281 		buf[idx++] = hdr->rad[i];
282 	buf[idx++] = (hdr->broadcast << 7) | (hdr->path_msg << 6) |
283 		(hdr->msg_len & 0x3f);
284 	buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4);
285 
286 	crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1);
287 	buf[idx - 1] |= (crc4 & 0xf);
288 
289 	*len = idx;
290 }
291 
292 static bool drm_dp_decode_sideband_msg_hdr(const struct drm_dp_mst_topology_mgr *mgr,
293 					   struct drm_dp_sideband_msg_hdr *hdr,
294 					   u8 *buf, int buflen, u8 *hdrlen)
295 {
296 	u8 crc4;
297 	u8 len;
298 	int i;
299 	u8 idx;
300 
301 	if (buf[0] == 0)
302 		return false;
303 	len = 3;
304 	len += ((buf[0] & 0xf0) >> 4) / 2;
305 	if (len > buflen)
306 		return false;
307 	crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1);
308 
309 	if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) {
310 		drm_dbg_kms(mgr->dev, "crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]);
311 		return false;
312 	}
313 
314 	hdr->lct = (buf[0] & 0xf0) >> 4;
315 	hdr->lcr = (buf[0] & 0xf);
316 	idx = 1;
317 	for (i = 0; i < (hdr->lct / 2); i++)
318 		hdr->rad[i] = buf[idx++];
319 	hdr->broadcast = (buf[idx] >> 7) & 0x1;
320 	hdr->path_msg = (buf[idx] >> 6) & 0x1;
321 	hdr->msg_len = buf[idx] & 0x3f;
322 	idx++;
323 	hdr->somt = (buf[idx] >> 7) & 0x1;
324 	hdr->eomt = (buf[idx] >> 6) & 0x1;
325 	hdr->seqno = (buf[idx] >> 4) & 0x1;
326 	idx++;
327 	*hdrlen = idx;
328 	return true;
329 }
330 
331 void
332 drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
333 			   struct drm_dp_sideband_msg_tx *raw)
334 {
335 	int idx = 0;
336 	int i;
337 	u8 *buf = raw->msg;
338 
339 	buf[idx++] = req->req_type & 0x7f;
340 
341 	switch (req->req_type) {
342 	case DP_ENUM_PATH_RESOURCES:
343 	case DP_POWER_DOWN_PHY:
344 	case DP_POWER_UP_PHY:
345 		buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
346 		idx++;
347 		break;
348 	case DP_ALLOCATE_PAYLOAD:
349 		buf[idx] = (req->u.allocate_payload.port_number & 0xf) << 4 |
350 			(req->u.allocate_payload.number_sdp_streams & 0xf);
351 		idx++;
352 		buf[idx] = (req->u.allocate_payload.vcpi & 0x7f);
353 		idx++;
354 		buf[idx] = (req->u.allocate_payload.pbn >> 8);
355 		idx++;
356 		buf[idx] = (req->u.allocate_payload.pbn & 0xff);
357 		idx++;
358 		for (i = 0; i < req->u.allocate_payload.number_sdp_streams / 2; i++) {
359 			buf[idx] = ((req->u.allocate_payload.sdp_stream_sink[i * 2] & 0xf) << 4) |
360 				(req->u.allocate_payload.sdp_stream_sink[i * 2 + 1] & 0xf);
361 			idx++;
362 		}
363 		if (req->u.allocate_payload.number_sdp_streams & 1) {
364 			i = req->u.allocate_payload.number_sdp_streams - 1;
365 			buf[idx] = (req->u.allocate_payload.sdp_stream_sink[i] & 0xf) << 4;
366 			idx++;
367 		}
368 		break;
369 	case DP_QUERY_PAYLOAD:
370 		buf[idx] = (req->u.query_payload.port_number & 0xf) << 4;
371 		idx++;
372 		buf[idx] = (req->u.query_payload.vcpi & 0x7f);
373 		idx++;
374 		break;
375 	case DP_REMOTE_DPCD_READ:
376 		buf[idx] = (req->u.dpcd_read.port_number & 0xf) << 4;
377 		buf[idx] |= ((req->u.dpcd_read.dpcd_address & 0xf0000) >> 16) & 0xf;
378 		idx++;
379 		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff00) >> 8;
380 		idx++;
381 		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff);
382 		idx++;
383 		buf[idx] = (req->u.dpcd_read.num_bytes);
384 		idx++;
385 		break;
386 
387 	case DP_REMOTE_DPCD_WRITE:
388 		buf[idx] = (req->u.dpcd_write.port_number & 0xf) << 4;
389 		buf[idx] |= ((req->u.dpcd_write.dpcd_address & 0xf0000) >> 16) & 0xf;
390 		idx++;
391 		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff00) >> 8;
392 		idx++;
393 		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff);
394 		idx++;
395 		buf[idx] = (req->u.dpcd_write.num_bytes);
396 		idx++;
397 		memcpy(&buf[idx], req->u.dpcd_write.bytes, req->u.dpcd_write.num_bytes);
398 		idx += req->u.dpcd_write.num_bytes;
399 		break;
400 	case DP_REMOTE_I2C_READ:
401 		buf[idx] = (req->u.i2c_read.port_number & 0xf) << 4;
402 		buf[idx] |= (req->u.i2c_read.num_transactions & 0x3);
403 		idx++;
404 		for (i = 0; i < (req->u.i2c_read.num_transactions & 0x3); i++) {
405 			buf[idx] = req->u.i2c_read.transactions[i].i2c_dev_id & 0x7f;
406 			idx++;
407 			buf[idx] = req->u.i2c_read.transactions[i].num_bytes;
408 			idx++;
409 			memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
410 			idx += req->u.i2c_read.transactions[i].num_bytes;
411 
412 			buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 4;
413 			buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
414 			idx++;
415 		}
416 		buf[idx] = (req->u.i2c_read.read_i2c_device_id) & 0x7f;
417 		idx++;
418 		buf[idx] = (req->u.i2c_read.num_bytes_read);
419 		idx++;
420 		break;
421 
422 	case DP_REMOTE_I2C_WRITE:
423 		buf[idx] = (req->u.i2c_write.port_number & 0xf) << 4;
424 		idx++;
425 		buf[idx] = (req->u.i2c_write.write_i2c_device_id) & 0x7f;
426 		idx++;
427 		buf[idx] = (req->u.i2c_write.num_bytes);
428 		idx++;
429 		memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
430 		idx += req->u.i2c_write.num_bytes;
431 		break;
432 	case DP_QUERY_STREAM_ENC_STATUS: {
433 		const struct drm_dp_query_stream_enc_status *msg;
434 
435 		msg = &req->u.enc_status;
436 		buf[idx] = msg->stream_id;
437 		idx++;
438 		memcpy(&buf[idx], msg->client_id, sizeof(msg->client_id));
439 		idx += sizeof(msg->client_id);
440 		buf[idx] = 0;
441 		buf[idx] |= FIELD_PREP(GENMASK(1, 0), msg->stream_event);
442 		buf[idx] |= msg->valid_stream_event ? BIT(2) : 0;
443 		buf[idx] |= FIELD_PREP(GENMASK(4, 3), msg->stream_behavior);
444 		buf[idx] |= msg->valid_stream_behavior ? BIT(5) : 0;
445 		idx++;
446 		}
447 		break;
448 	}
449 	raw->cur_len = idx;
450 }
451 EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_encode_sideband_req);
452 
453 /* Decode a sideband request we've encoded, mainly used for debugging */
454 int
455 drm_dp_decode_sideband_req(const struct drm_dp_sideband_msg_tx *raw,
456 			   struct drm_dp_sideband_msg_req_body *req)
457 {
458 	const u8 *buf = raw->msg;
459 	int i, idx = 0;
460 
461 	req->req_type = buf[idx++] & 0x7f;
462 	switch (req->req_type) {
463 	case DP_ENUM_PATH_RESOURCES:
464 	case DP_POWER_DOWN_PHY:
465 	case DP_POWER_UP_PHY:
466 		req->u.port_num.port_number = (buf[idx] >> 4) & 0xf;
467 		break;
468 	case DP_ALLOCATE_PAYLOAD:
469 		{
470 			struct drm_dp_allocate_payload *a =
471 				&req->u.allocate_payload;
472 
473 			a->number_sdp_streams = buf[idx] & 0xf;
474 			a->port_number = (buf[idx] >> 4) & 0xf;
475 
476 			WARN_ON(buf[++idx] & 0x80);
477 			a->vcpi = buf[idx] & 0x7f;
478 
479 			a->pbn = buf[++idx] << 8;
480 			a->pbn |= buf[++idx];
481 
482 			idx++;
483 			for (i = 0; i < a->number_sdp_streams; i++) {
484 				a->sdp_stream_sink[i] =
485 					(buf[idx + (i / 2)] >> ((i % 2) ? 0 : 4)) & 0xf;
486 			}
487 		}
488 		break;
489 	case DP_QUERY_PAYLOAD:
490 		req->u.query_payload.port_number = (buf[idx] >> 4) & 0xf;
491 		WARN_ON(buf[++idx] & 0x80);
492 		req->u.query_payload.vcpi = buf[idx] & 0x7f;
493 		break;
494 	case DP_REMOTE_DPCD_READ:
495 		{
496 			struct drm_dp_remote_dpcd_read *r = &req->u.dpcd_read;
497 
498 			r->port_number = (buf[idx] >> 4) & 0xf;
499 
500 			r->dpcd_address = (buf[idx] << 16) & 0xf0000;
501 			r->dpcd_address |= (buf[++idx] << 8) & 0xff00;
502 			r->dpcd_address |= buf[++idx] & 0xff;
503 
504 			r->num_bytes = buf[++idx];
505 		}
506 		break;
507 	case DP_REMOTE_DPCD_WRITE:
508 		{
509 			struct drm_dp_remote_dpcd_write *w =
510 				&req->u.dpcd_write;
511 
512 			w->port_number = (buf[idx] >> 4) & 0xf;
513 
514 			w->dpcd_address = (buf[idx] << 16) & 0xf0000;
515 			w->dpcd_address |= (buf[++idx] << 8) & 0xff00;
516 			w->dpcd_address |= buf[++idx] & 0xff;
517 
518 			w->num_bytes = buf[++idx];
519 
520 			w->bytes = kmemdup(&buf[++idx], w->num_bytes,
521 					   GFP_KERNEL);
522 			if (!w->bytes)
523 				return -ENOMEM;
524 		}
525 		break;
526 	case DP_REMOTE_I2C_READ:
527 		{
528 			struct drm_dp_remote_i2c_read *r = &req->u.i2c_read;
529 			struct drm_dp_remote_i2c_read_tx *tx;
530 			bool failed = false;
531 
532 			r->num_transactions = buf[idx] & 0x3;
533 			r->port_number = (buf[idx] >> 4) & 0xf;
534 			for (i = 0; i < r->num_transactions; i++) {
535 				tx = &r->transactions[i];
536 
537 				tx->i2c_dev_id = buf[++idx] & 0x7f;
538 				tx->num_bytes = buf[++idx];
539 				tx->bytes = kmemdup(&buf[++idx],
540 						    tx->num_bytes,
541 						    GFP_KERNEL);
542 				if (!tx->bytes) {
543 					failed = true;
544 					break;
545 				}
546 				idx += tx->num_bytes;
547 				tx->no_stop_bit = (buf[idx] >> 5) & 0x1;
548 				tx->i2c_transaction_delay = buf[idx] & 0xf;
549 			}
550 
551 			if (failed) {
552 				for (i = 0; i < r->num_transactions; i++) {
553 					tx = &r->transactions[i];
554 					kfree(tx->bytes);
555 				}
556 				return -ENOMEM;
557 			}
558 
559 			r->read_i2c_device_id = buf[++idx] & 0x7f;
560 			r->num_bytes_read = buf[++idx];
561 		}
562 		break;
563 	case DP_REMOTE_I2C_WRITE:
564 		{
565 			struct drm_dp_remote_i2c_write *w = &req->u.i2c_write;
566 
567 			w->port_number = (buf[idx] >> 4) & 0xf;
568 			w->write_i2c_device_id = buf[++idx] & 0x7f;
569 			w->num_bytes = buf[++idx];
570 			w->bytes = kmemdup(&buf[++idx], w->num_bytes,
571 					   GFP_KERNEL);
572 			if (!w->bytes)
573 				return -ENOMEM;
574 		}
575 		break;
576 	case DP_QUERY_STREAM_ENC_STATUS:
577 		req->u.enc_status.stream_id = buf[idx++];
578 		for (i = 0; i < sizeof(req->u.enc_status.client_id); i++)
579 			req->u.enc_status.client_id[i] = buf[idx++];
580 
581 		req->u.enc_status.stream_event = FIELD_GET(GENMASK(1, 0),
582 							   buf[idx]);
583 		req->u.enc_status.valid_stream_event = FIELD_GET(BIT(2),
584 								 buf[idx]);
585 		req->u.enc_status.stream_behavior = FIELD_GET(GENMASK(4, 3),
586 							      buf[idx]);
587 		req->u.enc_status.valid_stream_behavior = FIELD_GET(BIT(5),
588 								    buf[idx]);
589 		break;
590 	}
591 
592 	return 0;
593 }
594 EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_decode_sideband_req);
595 
596 void
597 drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req,
598 				  int indent, struct drm_printer *printer)
599 {
600 	int i;
601 
602 #define P(f, ...) drm_printf_indent(printer, indent, f, ##__VA_ARGS__)
603 	if (req->req_type == DP_LINK_ADDRESS) {
604 		/* No contents to print */
605 		P("type=%s\n", drm_dp_mst_req_type_str(req->req_type));
606 		return;
607 	}
608 
609 	P("type=%s contents:\n", drm_dp_mst_req_type_str(req->req_type));
610 	indent++;
611 
612 	switch (req->req_type) {
613 	case DP_ENUM_PATH_RESOURCES:
614 	case DP_POWER_DOWN_PHY:
615 	case DP_POWER_UP_PHY:
616 		P("port=%d\n", req->u.port_num.port_number);
617 		break;
618 	case DP_ALLOCATE_PAYLOAD:
619 		P("port=%d vcpi=%d pbn=%d sdp_streams=%d %*ph\n",
620 		  req->u.allocate_payload.port_number,
621 		  req->u.allocate_payload.vcpi, req->u.allocate_payload.pbn,
622 		  req->u.allocate_payload.number_sdp_streams,
623 		  req->u.allocate_payload.number_sdp_streams,
624 		  req->u.allocate_payload.sdp_stream_sink);
625 		break;
626 	case DP_QUERY_PAYLOAD:
627 		P("port=%d vcpi=%d\n",
628 		  req->u.query_payload.port_number,
629 		  req->u.query_payload.vcpi);
630 		break;
631 	case DP_REMOTE_DPCD_READ:
632 		P("port=%d dpcd_addr=%05x len=%d\n",
633 		  req->u.dpcd_read.port_number, req->u.dpcd_read.dpcd_address,
634 		  req->u.dpcd_read.num_bytes);
635 		break;
636 	case DP_REMOTE_DPCD_WRITE:
637 		P("port=%d addr=%05x len=%d: %*ph\n",
638 		  req->u.dpcd_write.port_number,
639 		  req->u.dpcd_write.dpcd_address,
640 		  req->u.dpcd_write.num_bytes, req->u.dpcd_write.num_bytes,
641 		  req->u.dpcd_write.bytes);
642 		break;
643 	case DP_REMOTE_I2C_READ:
644 		P("port=%d num_tx=%d id=%d size=%d:\n",
645 		  req->u.i2c_read.port_number,
646 		  req->u.i2c_read.num_transactions,
647 		  req->u.i2c_read.read_i2c_device_id,
648 		  req->u.i2c_read.num_bytes_read);
649 
650 		indent++;
651 		for (i = 0; i < req->u.i2c_read.num_transactions; i++) {
652 			const struct drm_dp_remote_i2c_read_tx *rtx =
653 				&req->u.i2c_read.transactions[i];
654 
655 			P("%d: id=%03d size=%03d no_stop_bit=%d tx_delay=%03d: %*ph\n",
656 			  i, rtx->i2c_dev_id, rtx->num_bytes,
657 			  rtx->no_stop_bit, rtx->i2c_transaction_delay,
658 			  rtx->num_bytes, rtx->bytes);
659 		}
660 		break;
661 	case DP_REMOTE_I2C_WRITE:
662 		P("port=%d id=%d size=%d: %*ph\n",
663 		  req->u.i2c_write.port_number,
664 		  req->u.i2c_write.write_i2c_device_id,
665 		  req->u.i2c_write.num_bytes, req->u.i2c_write.num_bytes,
666 		  req->u.i2c_write.bytes);
667 		break;
668 	case DP_QUERY_STREAM_ENC_STATUS:
669 		P("stream_id=%u client_id=%*ph stream_event=%x "
670 		  "valid_event=%d stream_behavior=%x valid_behavior=%d",
671 		  req->u.enc_status.stream_id,
672 		  (int)ARRAY_SIZE(req->u.enc_status.client_id),
673 		  req->u.enc_status.client_id, req->u.enc_status.stream_event,
674 		  req->u.enc_status.valid_stream_event,
675 		  req->u.enc_status.stream_behavior,
676 		  req->u.enc_status.valid_stream_behavior);
677 		break;
678 	default:
679 		P("???\n");
680 		break;
681 	}
682 #undef P
683 }
684 EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_dump_sideband_msg_req_body);
685 
686 static inline void
687 drm_dp_mst_dump_sideband_msg_tx(struct drm_printer *p,
688 				const struct drm_dp_sideband_msg_tx *txmsg)
689 {
690 	struct drm_dp_sideband_msg_req_body req;
691 	char buf[64];
692 	int ret;
693 	int i;
694 
695 	drm_dp_mst_rad_to_str(txmsg->dst->rad, txmsg->dst->lct, buf,
696 			      sizeof(buf));
697 	drm_printf(p, "txmsg cur_offset=%x cur_len=%x seqno=%x state=%s path_msg=%d dst=%s\n",
698 		   txmsg->cur_offset, txmsg->cur_len, txmsg->seqno,
699 		   drm_dp_mst_sideband_tx_state_str(txmsg->state),
700 		   txmsg->path_msg, buf);
701 
702 	ret = drm_dp_decode_sideband_req(txmsg, &req);
703 	if (ret) {
704 		drm_printf(p, "<failed to decode sideband req: %d>\n", ret);
705 		return;
706 	}
707 	drm_dp_dump_sideband_msg_req_body(&req, 1, p);
708 
709 	switch (req.req_type) {
710 	case DP_REMOTE_DPCD_WRITE:
711 		kfree(req.u.dpcd_write.bytes);
712 		break;
713 	case DP_REMOTE_I2C_READ:
714 		for (i = 0; i < req.u.i2c_read.num_transactions; i++)
715 			kfree(req.u.i2c_read.transactions[i].bytes);
716 		break;
717 	case DP_REMOTE_I2C_WRITE:
718 		kfree(req.u.i2c_write.bytes);
719 		break;
720 	}
721 }
722 
723 static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len)
724 {
725 	u8 crc4;
726 
727 	crc4 = drm_dp_msg_data_crc4(msg, len);
728 	msg[len] = crc4;
729 }
730 
731 static void drm_dp_encode_sideband_reply(struct drm_dp_sideband_msg_reply_body *rep,
732 					 struct drm_dp_sideband_msg_tx *raw)
733 {
734 	int idx = 0;
735 	u8 *buf = raw->msg;
736 
737 	buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
738 
739 	raw->cur_len = idx;
740 }
741 
742 static int drm_dp_sideband_msg_set_header(struct drm_dp_sideband_msg_rx *msg,
743 					  struct drm_dp_sideband_msg_hdr *hdr,
744 					  u8 hdrlen)
745 {
746 	/*
747 	 * ignore out-of-order messages or messages that are part of a
748 	 * failed transaction
749 	 */
750 	if (!hdr->somt && !msg->have_somt)
751 		return false;
752 
753 	/* get length contained in this portion */
754 	msg->curchunk_idx = 0;
755 	msg->curchunk_len = hdr->msg_len;
756 	msg->curchunk_hdrlen = hdrlen;
757 
758 	/* we have already gotten an somt - don't bother parsing */
759 	if (hdr->somt && msg->have_somt)
760 		return false;
761 
762 	if (hdr->somt) {
763 		memcpy(&msg->initial_hdr, hdr,
764 		       sizeof(struct drm_dp_sideband_msg_hdr));
765 		msg->have_somt = true;
766 	}
767 	if (hdr->eomt)
768 		msg->have_eomt = true;
769 
770 	return true;
771 }
772 
773 /* this adds a chunk of msg to the builder to get the final msg */
774 static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg,
775 					   u8 *replybuf, u8 replybuflen)
776 {
777 	u8 crc4;
778 
779 	memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
780 	msg->curchunk_idx += replybuflen;
781 
782 	if (msg->curchunk_idx >= msg->curchunk_len) {
783 		/* do CRC */
784 		crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1);
785 		if (crc4 != msg->chunk[msg->curchunk_len - 1])
786 			print_hex_dump(KERN_DEBUG, "wrong crc",
787 				       DUMP_PREFIX_NONE, 16, 1,
788 				       msg->chunk,  msg->curchunk_len, false);
789 		/* copy chunk into bigger msg */
790 		memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
791 		msg->curlen += msg->curchunk_len - 1;
792 	}
793 	return true;
794 }
795 
796 static bool drm_dp_sideband_parse_link_address(const struct drm_dp_mst_topology_mgr *mgr,
797 					       struct drm_dp_sideband_msg_rx *raw,
798 					       struct drm_dp_sideband_msg_reply_body *repmsg)
799 {
800 	int idx = 1;
801 	int i;
802 
803 	memcpy(repmsg->u.link_addr.guid, &raw->msg[idx], 16);
804 	idx += 16;
805 	repmsg->u.link_addr.nports = raw->msg[idx] & 0xf;
806 	idx++;
807 	if (idx > raw->curlen)
808 		goto fail_len;
809 	for (i = 0; i < repmsg->u.link_addr.nports; i++) {
810 		if (raw->msg[idx] & 0x80)
811 			repmsg->u.link_addr.ports[i].input_port = 1;
812 
813 		repmsg->u.link_addr.ports[i].peer_device_type = (raw->msg[idx] >> 4) & 0x7;
814 		repmsg->u.link_addr.ports[i].port_number = (raw->msg[idx] & 0xf);
815 
816 		idx++;
817 		if (idx > raw->curlen)
818 			goto fail_len;
819 		repmsg->u.link_addr.ports[i].mcs = (raw->msg[idx] >> 7) & 0x1;
820 		repmsg->u.link_addr.ports[i].ddps = (raw->msg[idx] >> 6) & 0x1;
821 		if (repmsg->u.link_addr.ports[i].input_port == 0)
822 			repmsg->u.link_addr.ports[i].legacy_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
823 		idx++;
824 		if (idx > raw->curlen)
825 			goto fail_len;
826 		if (repmsg->u.link_addr.ports[i].input_port == 0) {
827 			repmsg->u.link_addr.ports[i].dpcd_revision = (raw->msg[idx]);
828 			idx++;
829 			if (idx > raw->curlen)
830 				goto fail_len;
831 			memcpy(repmsg->u.link_addr.ports[i].peer_guid, &raw->msg[idx], 16);
832 			idx += 16;
833 			if (idx > raw->curlen)
834 				goto fail_len;
835 			repmsg->u.link_addr.ports[i].num_sdp_streams = (raw->msg[idx] >> 4) & 0xf;
836 			repmsg->u.link_addr.ports[i].num_sdp_stream_sinks = (raw->msg[idx] & 0xf);
837 			idx++;
838 
839 		}
840 		if (idx > raw->curlen)
841 			goto fail_len;
842 	}
843 
844 	return true;
845 fail_len:
846 	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
847 	return false;
848 }
849 
850 static bool drm_dp_sideband_parse_remote_dpcd_read(struct drm_dp_sideband_msg_rx *raw,
851 						   struct drm_dp_sideband_msg_reply_body *repmsg)
852 {
853 	int idx = 1;
854 
855 	repmsg->u.remote_dpcd_read_ack.port_number = raw->msg[idx] & 0xf;
856 	idx++;
857 	if (idx > raw->curlen)
858 		goto fail_len;
859 	repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
860 	idx++;
861 	if (idx > raw->curlen)
862 		goto fail_len;
863 
864 	memcpy(repmsg->u.remote_dpcd_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_dpcd_read_ack.num_bytes);
865 	return true;
866 fail_len:
867 	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
868 	return false;
869 }
870 
871 static bool drm_dp_sideband_parse_remote_dpcd_write(struct drm_dp_sideband_msg_rx *raw,
872 						      struct drm_dp_sideband_msg_reply_body *repmsg)
873 {
874 	int idx = 1;
875 
876 	repmsg->u.remote_dpcd_write_ack.port_number = raw->msg[idx] & 0xf;
877 	idx++;
878 	if (idx > raw->curlen)
879 		goto fail_len;
880 	return true;
881 fail_len:
882 	DRM_DEBUG_KMS("parse length fail %d %d\n", idx, raw->curlen);
883 	return false;
884 }
885 
886 static bool drm_dp_sideband_parse_remote_i2c_read_ack(struct drm_dp_sideband_msg_rx *raw,
887 						      struct drm_dp_sideband_msg_reply_body *repmsg)
888 {
889 	int idx = 1;
890 
891 	repmsg->u.remote_i2c_read_ack.port_number = (raw->msg[idx] & 0xf);
892 	idx++;
893 	if (idx > raw->curlen)
894 		goto fail_len;
895 	repmsg->u.remote_i2c_read_ack.num_bytes = raw->msg[idx];
896 	idx++;
897 	/* TODO check */
898 	memcpy(repmsg->u.remote_i2c_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_i2c_read_ack.num_bytes);
899 	return true;
900 fail_len:
901 	DRM_DEBUG_KMS("remote i2c reply parse length fail %d %d\n", idx, raw->curlen);
902 	return false;
903 }
904 
905 static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband_msg_rx *raw,
906 							  struct drm_dp_sideband_msg_reply_body *repmsg)
907 {
908 	int idx = 1;
909 
910 	repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
911 	repmsg->u.path_resources.fec_capable = raw->msg[idx] & 0x1;
912 	idx++;
913 	if (idx > raw->curlen)
914 		goto fail_len;
915 	repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
916 	idx += 2;
917 	if (idx > raw->curlen)
918 		goto fail_len;
919 	repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
920 	idx += 2;
921 	if (idx > raw->curlen)
922 		goto fail_len;
923 	return true;
924 fail_len:
925 	DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen);
926 	return false;
927 }
928 
929 static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_msg_rx *raw,
930 							  struct drm_dp_sideband_msg_reply_body *repmsg)
931 {
932 	int idx = 1;
933 
934 	repmsg->u.allocate_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
935 	idx++;
936 	if (idx > raw->curlen)
937 		goto fail_len;
938 	repmsg->u.allocate_payload.vcpi = raw->msg[idx];
939 	idx++;
940 	if (idx > raw->curlen)
941 		goto fail_len;
942 	repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
943 	idx += 2;
944 	if (idx > raw->curlen)
945 		goto fail_len;
946 	return true;
947 fail_len:
948 	DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen);
949 	return false;
950 }
951 
952 static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_rx *raw,
953 						    struct drm_dp_sideband_msg_reply_body *repmsg)
954 {
955 	int idx = 1;
956 
957 	repmsg->u.query_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
958 	idx++;
959 	if (idx > raw->curlen)
960 		goto fail_len;
961 	repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
962 	idx += 2;
963 	if (idx > raw->curlen)
964 		goto fail_len;
965 	return true;
966 fail_len:
967 	DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen);
968 	return false;
969 }
970 
971 static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_msg_rx *raw,
972 						       struct drm_dp_sideband_msg_reply_body *repmsg)
973 {
974 	int idx = 1;
975 
976 	repmsg->u.port_number.port_number = (raw->msg[idx] >> 4) & 0xf;
977 	idx++;
978 	if (idx > raw->curlen) {
979 		DRM_DEBUG_KMS("power up/down phy parse length fail %d %d\n",
980 			      idx, raw->curlen);
981 		return false;
982 	}
983 	return true;
984 }
985 
986 static bool
987 drm_dp_sideband_parse_query_stream_enc_status(
988 				struct drm_dp_sideband_msg_rx *raw,
989 				struct drm_dp_sideband_msg_reply_body *repmsg)
990 {
991 	struct drm_dp_query_stream_enc_status_ack_reply *reply;
992 
993 	reply = &repmsg->u.enc_status;
994 
995 	reply->stream_id = raw->msg[3];
996 
997 	reply->reply_signed = raw->msg[2] & BIT(0);
998 
999 	/*
1000 	 * NOTE: It's my impression from reading the spec that the below parsing
1001 	 * is correct. However I noticed while testing with an HDCP 1.4 display
1002 	 * through an HDCP 2.2 hub that only bit 3 was set. In that case, I
1003 	 * would expect both bits to be set. So keep the parsing following the
1004 	 * spec, but beware reality might not match the spec (at least for some
1005 	 * configurations).
1006 	 */
1007 	reply->hdcp_1x_device_present = raw->msg[2] & BIT(4);
1008 	reply->hdcp_2x_device_present = raw->msg[2] & BIT(3);
1009 
1010 	reply->query_capable_device_present = raw->msg[2] & BIT(5);
1011 	reply->legacy_device_present = raw->msg[2] & BIT(6);
1012 	reply->unauthorizable_device_present = raw->msg[2] & BIT(7);
1013 
1014 	reply->auth_completed = !!(raw->msg[1] & BIT(3));
1015 	reply->encryption_enabled = !!(raw->msg[1] & BIT(4));
1016 	reply->repeater_present = !!(raw->msg[1] & BIT(5));
1017 	reply->state = (raw->msg[1] & GENMASK(7, 6)) >> 6;
1018 
1019 	return true;
1020 }
1021 
1022 static bool drm_dp_sideband_parse_reply(const struct drm_dp_mst_topology_mgr *mgr,
1023 					struct drm_dp_sideband_msg_rx *raw,
1024 					struct drm_dp_sideband_msg_reply_body *msg)
1025 {
1026 	memset(msg, 0, sizeof(*msg));
1027 	msg->reply_type = (raw->msg[0] & 0x80) >> 7;
1028 	msg->req_type = (raw->msg[0] & 0x7f);
1029 
1030 	if (msg->reply_type == DP_SIDEBAND_REPLY_NAK) {
1031 		memcpy(msg->u.nak.guid, &raw->msg[1], 16);
1032 		msg->u.nak.reason = raw->msg[17];
1033 		msg->u.nak.nak_data = raw->msg[18];
1034 		return false;
1035 	}
1036 
1037 	switch (msg->req_type) {
1038 	case DP_LINK_ADDRESS:
1039 		return drm_dp_sideband_parse_link_address(mgr, raw, msg);
1040 	case DP_QUERY_PAYLOAD:
1041 		return drm_dp_sideband_parse_query_payload_ack(raw, msg);
1042 	case DP_REMOTE_DPCD_READ:
1043 		return drm_dp_sideband_parse_remote_dpcd_read(raw, msg);
1044 	case DP_REMOTE_DPCD_WRITE:
1045 		return drm_dp_sideband_parse_remote_dpcd_write(raw, msg);
1046 	case DP_REMOTE_I2C_READ:
1047 		return drm_dp_sideband_parse_remote_i2c_read_ack(raw, msg);
1048 	case DP_REMOTE_I2C_WRITE:
1049 		return true; /* since there's nothing to parse */
1050 	case DP_ENUM_PATH_RESOURCES:
1051 		return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
1052 	case DP_ALLOCATE_PAYLOAD:
1053 		return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
1054 	case DP_POWER_DOWN_PHY:
1055 	case DP_POWER_UP_PHY:
1056 		return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
1057 	case DP_CLEAR_PAYLOAD_ID_TABLE:
1058 		return true; /* since there's nothing to parse */
1059 	case DP_QUERY_STREAM_ENC_STATUS:
1060 		return drm_dp_sideband_parse_query_stream_enc_status(raw, msg);
1061 	default:
1062 		drm_err(mgr->dev, "Got unknown reply 0x%02x (%s)\n",
1063 			msg->req_type, drm_dp_mst_req_type_str(msg->req_type));
1064 		return false;
1065 	}
1066 }
1067 
1068 static bool
1069 drm_dp_sideband_parse_connection_status_notify(const struct drm_dp_mst_topology_mgr *mgr,
1070 					       struct drm_dp_sideband_msg_rx *raw,
1071 					       struct drm_dp_sideband_msg_req_body *msg)
1072 {
1073 	int idx = 1;
1074 
1075 	msg->u.conn_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
1076 	idx++;
1077 	if (idx > raw->curlen)
1078 		goto fail_len;
1079 
1080 	memcpy(msg->u.conn_stat.guid, &raw->msg[idx], 16);
1081 	idx += 16;
1082 	if (idx > raw->curlen)
1083 		goto fail_len;
1084 
1085 	msg->u.conn_stat.legacy_device_plug_status = (raw->msg[idx] >> 6) & 0x1;
1086 	msg->u.conn_stat.displayport_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
1087 	msg->u.conn_stat.message_capability_status = (raw->msg[idx] >> 4) & 0x1;
1088 	msg->u.conn_stat.input_port = (raw->msg[idx] >> 3) & 0x1;
1089 	msg->u.conn_stat.peer_device_type = (raw->msg[idx] & 0x7);
1090 	idx++;
1091 	return true;
1092 fail_len:
1093 	drm_dbg_kms(mgr->dev, "connection status reply parse length fail %d %d\n",
1094 		    idx, raw->curlen);
1095 	return false;
1096 }
1097 
1098 static bool drm_dp_sideband_parse_resource_status_notify(const struct drm_dp_mst_topology_mgr *mgr,
1099 							 struct drm_dp_sideband_msg_rx *raw,
1100 							 struct drm_dp_sideband_msg_req_body *msg)
1101 {
1102 	int idx = 1;
1103 
1104 	msg->u.resource_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
1105 	idx++;
1106 	if (idx > raw->curlen)
1107 		goto fail_len;
1108 
1109 	memcpy(msg->u.resource_stat.guid, &raw->msg[idx], 16);
1110 	idx += 16;
1111 	if (idx > raw->curlen)
1112 		goto fail_len;
1113 
1114 	msg->u.resource_stat.available_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
1115 	idx++;
1116 	return true;
1117 fail_len:
1118 	drm_dbg_kms(mgr->dev, "resource status reply parse length fail %d %d\n", idx, raw->curlen);
1119 	return false;
1120 }
1121 
1122 static bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
1123 				      struct drm_dp_sideband_msg_rx *raw,
1124 				      struct drm_dp_sideband_msg_req_body *msg)
1125 {
1126 	memset(msg, 0, sizeof(*msg));
1127 	msg->req_type = (raw->msg[0] & 0x7f);
1128 
1129 	switch (msg->req_type) {
1130 	case DP_CONNECTION_STATUS_NOTIFY:
1131 		return drm_dp_sideband_parse_connection_status_notify(mgr, raw, msg);
1132 	case DP_RESOURCE_STATUS_NOTIFY:
1133 		return drm_dp_sideband_parse_resource_status_notify(mgr, raw, msg);
1134 	default:
1135 		drm_err(mgr->dev, "Got unknown request 0x%02x (%s)\n",
1136 			msg->req_type, drm_dp_mst_req_type_str(msg->req_type));
1137 		return false;
1138 	}
1139 }
1140 
1141 static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,
1142 			     u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
1143 {
1144 	struct drm_dp_sideband_msg_req_body req;
1145 
1146 	req.req_type = DP_REMOTE_DPCD_WRITE;
1147 	req.u.dpcd_write.port_number = port_num;
1148 	req.u.dpcd_write.dpcd_address = offset;
1149 	req.u.dpcd_write.num_bytes = num_bytes;
1150 	req.u.dpcd_write.bytes = bytes;
1151 	drm_dp_encode_sideband_req(&req, msg);
1152 }
1153 
1154 static void build_link_address(struct drm_dp_sideband_msg_tx *msg)
1155 {
1156 	struct drm_dp_sideband_msg_req_body req;
1157 
1158 	req.req_type = DP_LINK_ADDRESS;
1159 	drm_dp_encode_sideband_req(&req, msg);
1160 }
1161 
1162 static void build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg)
1163 {
1164 	struct drm_dp_sideband_msg_req_body req;
1165 
1166 	req.req_type = DP_CLEAR_PAYLOAD_ID_TABLE;
1167 	drm_dp_encode_sideband_req(&req, msg);
1168 	msg->path_msg = true;
1169 }
1170 
1171 static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg,
1172 				     int port_num)
1173 {
1174 	struct drm_dp_sideband_msg_req_body req;
1175 
1176 	req.req_type = DP_ENUM_PATH_RESOURCES;
1177 	req.u.port_num.port_number = port_num;
1178 	drm_dp_encode_sideband_req(&req, msg);
1179 	msg->path_msg = true;
1180 	return 0;
1181 }
1182 
1183 static void build_allocate_payload(struct drm_dp_sideband_msg_tx *msg,
1184 				   int port_num,
1185 				   u8 vcpi, uint16_t pbn,
1186 				   u8 number_sdp_streams,
1187 				   u8 *sdp_stream_sink)
1188 {
1189 	struct drm_dp_sideband_msg_req_body req;
1190 
1191 	memset(&req, 0, sizeof(req));
1192 	req.req_type = DP_ALLOCATE_PAYLOAD;
1193 	req.u.allocate_payload.port_number = port_num;
1194 	req.u.allocate_payload.vcpi = vcpi;
1195 	req.u.allocate_payload.pbn = pbn;
1196 	req.u.allocate_payload.number_sdp_streams = number_sdp_streams;
1197 	memcpy(req.u.allocate_payload.sdp_stream_sink, sdp_stream_sink,
1198 		   number_sdp_streams);
1199 	drm_dp_encode_sideband_req(&req, msg);
1200 	msg->path_msg = true;
1201 }
1202 
1203 static void build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
1204 				   int port_num, bool power_up)
1205 {
1206 	struct drm_dp_sideband_msg_req_body req;
1207 
1208 	if (power_up)
1209 		req.req_type = DP_POWER_UP_PHY;
1210 	else
1211 		req.req_type = DP_POWER_DOWN_PHY;
1212 
1213 	req.u.port_num.port_number = port_num;
1214 	drm_dp_encode_sideband_req(&req, msg);
1215 	msg->path_msg = true;
1216 }
1217 
1218 static int
1219 build_query_stream_enc_status(struct drm_dp_sideband_msg_tx *msg, u8 stream_id,
1220 			      u8 *q_id)
1221 {
1222 	struct drm_dp_sideband_msg_req_body req;
1223 
1224 	req.req_type = DP_QUERY_STREAM_ENC_STATUS;
1225 	req.u.enc_status.stream_id = stream_id;
1226 	memcpy(req.u.enc_status.client_id, q_id,
1227 	       sizeof(req.u.enc_status.client_id));
1228 	req.u.enc_status.stream_event = 0;
1229 	req.u.enc_status.valid_stream_event = false;
1230 	req.u.enc_status.stream_behavior = 0;
1231 	req.u.enc_status.valid_stream_behavior = false;
1232 
1233 	drm_dp_encode_sideband_req(&req, msg);
1234 	return 0;
1235 }
1236 
1237 static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
1238 			      struct drm_dp_sideband_msg_tx *txmsg)
1239 {
1240 	unsigned int state;
1241 
1242 	/*
1243 	 * All updates to txmsg->state are protected by mgr->qlock, and the two
1244 	 * cases we check here are terminal states. For those the barriers
1245 	 * provided by the wake_up/wait_event pair are enough.
1246 	 */
1247 	state = READ_ONCE(txmsg->state);
1248 	return (state == DRM_DP_SIDEBAND_TX_RX ||
1249 		state == DRM_DP_SIDEBAND_TX_TIMEOUT);
1250 }
1251 
1252 static int drm_dp_mst_wait_tx_reply(struct drm_dp_mst_branch *mstb,
1253 				    struct drm_dp_sideband_msg_tx *txmsg)
1254 {
1255 	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1256 	unsigned long wait_timeout = msecs_to_jiffies(4000);
1257 	unsigned long wait_expires = jiffies + wait_timeout;
1258 	int ret;
1259 
1260 	for (;;) {
1261 		/*
1262 		 * If the driver provides a way for this, change to
1263 		 * poll-waiting for the MST reply interrupt if we didn't receive
1264 		 * it for 50 msec. This would cater for cases where the HPD
1265 		 * pulse signal got lost somewhere, even though the sink raised
1266 		 * the corresponding MST interrupt correctly. One example is the
1267 		 * Club 3D CAC-1557 TypeC -> DP adapter which for some reason
1268 		 * filters out short pulses with a duration less than ~540 usec.
1269 		 *
1270 		 * The poll period is 50 msec to avoid missing an interrupt
1271 		 * after the sink has cleared it (after a 110msec timeout
1272 		 * since it raised the interrupt).
1273 		 */
1274 		ret = wait_event_timeout(mgr->tx_waitq,
1275 					 check_txmsg_state(mgr, txmsg),
1276 					 mgr->cbs->poll_hpd_irq ?
1277 						msecs_to_jiffies(50) :
1278 						wait_timeout);
1279 
1280 		if (ret || !mgr->cbs->poll_hpd_irq ||
1281 		    time_after(jiffies, wait_expires))
1282 			break;
1283 
1284 		mgr->cbs->poll_hpd_irq(mgr);
1285 	}
1286 
1287 	mutex_lock(&mgr->qlock);
1288 	if (ret > 0) {
1289 		if (txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT) {
1290 			ret = -EIO;
1291 			goto out;
1292 		}
1293 	} else {
1294 		drm_dbg_kms(mgr->dev, "timedout msg send %p %d %d\n",
1295 			    txmsg, txmsg->state, txmsg->seqno);
1296 
1297 		/* dump some state */
1298 		ret = -EIO;
1299 
1300 		/* remove from q */
1301 		if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED ||
1302 		    txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
1303 		    txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
1304 			list_del(&txmsg->next);
1305 	}
1306 out:
1307 	if (unlikely(ret == -EIO) && drm_debug_enabled(DRM_UT_DP)) {
1308 		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
1309 
1310 		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
1311 	}
1312 	mutex_unlock(&mgr->qlock);
1313 
1314 	drm_dp_mst_kick_tx(mgr);
1315 	return ret;
1316 }
1317 
1318 static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
1319 {
1320 	struct drm_dp_mst_branch *mstb;
1321 
1322 	mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
1323 	if (!mstb)
1324 		return NULL;
1325 
1326 	mstb->lct = lct;
1327 	if (lct > 1)
1328 		memcpy(mstb->rad, rad, lct / 2);
1329 	INIT_LIST_HEAD(&mstb->ports);
1330 	kref_init(&mstb->topology_kref);
1331 	kref_init(&mstb->malloc_kref);
1332 	return mstb;
1333 }
1334 
1335 static void drm_dp_free_mst_branch_device(struct kref *kref)
1336 {
1337 	struct drm_dp_mst_branch *mstb =
1338 		container_of(kref, struct drm_dp_mst_branch, malloc_kref);
1339 
1340 	if (mstb->port_parent)
1341 		drm_dp_mst_put_port_malloc(mstb->port_parent);
1342 
1343 	kfree(mstb);
1344 }
1345 
1346 /**
1347  * DOC: Branch device and port refcounting
1348  *
1349  * Topology refcount overview
1350  * ~~~~~~~~~~~~~~~~~~~~~~~~~~
1351  *
1352  * The refcounting schemes for &struct drm_dp_mst_branch and &struct
1353  * drm_dp_mst_port are somewhat unusual. Both ports and branch devices have
1354  * two different kinds of refcounts: topology refcounts, and malloc refcounts.
1355  *
1356  * Topology refcounts are not exposed to drivers, and are handled internally
1357  * by the DP MST helpers. The helpers use them in order to prevent the
1358  * in-memory topology state from being changed in the middle of critical
1359  * operations like changing the internal state of payload allocations. This
1360  * means each branch and port will be considered to be connected to the rest
1361  * of the topology until its topology refcount reaches zero. Additionally,
1362  * for ports this means that their associated &struct drm_connector will stay
1363  * registered with userspace until the port's refcount reaches 0.
1364  *
1365  * Malloc refcount overview
1366  * ~~~~~~~~~~~~~~~~~~~~~~~~
1367  *
1368  * Malloc references are used to keep a &struct drm_dp_mst_port or &struct
1369  * drm_dp_mst_branch allocated even after all of its topology references have
1370  * been dropped, so that the driver or MST helpers can safely access each
1371  * branch's last known state before it was disconnected from the topology.
1372  * When the malloc refcount of a port or branch reaches 0, the memory
1373  * allocation containing the &struct drm_dp_mst_branch or &struct
1374  * drm_dp_mst_port respectively will be freed.
1375  *
1376  * For &struct drm_dp_mst_branch, malloc refcounts are not currently exposed
1377  * to drivers. As of writing this documentation, there are no drivers that
1378  * have a usecase for accessing &struct drm_dp_mst_branch outside of the MST
1379  * helpers. Exposing this API to drivers in a race-free manner would take more
1380  * tweaking of the refcounting scheme, however patches are welcome provided
1381  * there is a legitimate driver usecase for this.
1382  *
1383  * Refcount relationships in a topology
1384  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1385  *
1386  * Let's take a look at why the relationship between topology and malloc
1387  * refcounts is designed the way it is.
1388  *
1389  * .. kernel-figure:: dp-mst/topology-figure-1.dot
1390  *
1391  *    An example of topology and malloc refs in a DP MST topology with two
1392  *    active payloads. Topology refcount increments are indicated by solid
1393  *    lines, and malloc refcount increments are indicated by dashed lines.
1394  *    Each starts from the branch which incremented the refcount, and ends at
1395  *    the branch to which the refcount belongs to, i.e. the arrow points the
1396  *    same way as the C pointers used to reference a structure.
1397  *
1398  * As you can see in the above figure, every branch increments the topology
1399  * refcount of its children, and increments the malloc refcount of its
1400  * parent. Additionally, every payload increments the malloc refcount of its
1401  * assigned port by 1.
1402  *
1403  * So, what would happen if MSTB #3 from the above figure was unplugged from
1404  * the system, but the driver hadn't yet removed payload #2 from port #3? The
1405  * topology would start to look like the figure below.
1406  *
1407  * .. kernel-figure:: dp-mst/topology-figure-2.dot
1408  *
1409  *    Ports and branch devices which have been released from memory are
1410  *    colored grey, and references which have been removed are colored red.
1411  *
1412  * Whenever a port or branch device's topology refcount reaches zero, it will
1413  * decrement the topology refcounts of all its children, the malloc refcount
1414  * of its parent, and finally its own malloc refcount. For MSTB #4 and port
1415  * #4, this means they both have been disconnected from the topology and freed
1416  * from memory. But, because payload #2 is still holding a reference to port
1417  * #3, port #3 is removed from the topology but its &struct drm_dp_mst_port
1418  * is still accessible from memory. This also means port #3 has not yet
1419  * decremented the malloc refcount of MSTB #3, so its &struct
1420  * drm_dp_mst_branch will also stay allocated in memory until port #3's
1421  * malloc refcount reaches 0.
1422  *
1423  * This relationship is necessary because in order to release payload #2, we
1424  * need to be able to figure out the last relative of port #3 that's still
1425  * connected to the topology. In this case, we would travel up the topology as
1426  * shown below.
1427  *
1428  * .. kernel-figure:: dp-mst/topology-figure-3.dot
1429  *
1430  * And finally, remove payload #2 by communicating with port #2 through
1431  * sideband transactions.
1432  */
1433 
1434 /**
1435  * drm_dp_mst_get_mstb_malloc() - Increment the malloc refcount of a branch
1436  * device
1437  * @mstb: The &struct drm_dp_mst_branch to increment the malloc refcount of
1438  *
1439  * Increments &drm_dp_mst_branch.malloc_kref. When
1440  * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1441  * will be released and @mstb may no longer be used.
1442  *
1443  * See also: drm_dp_mst_put_mstb_malloc()
1444  */
1445 static void
1446 drm_dp_mst_get_mstb_malloc(struct drm_dp_mst_branch *mstb)
1447 {
1448 	kref_get(&mstb->malloc_kref);
1449 	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref));
1450 }
1451 
1452 /**
1453  * drm_dp_mst_put_mstb_malloc() - Decrement the malloc refcount of a branch
1454  * device
1455  * @mstb: The &struct drm_dp_mst_branch to decrement the malloc refcount of
1456  *
1457  * Decrements &drm_dp_mst_branch.malloc_kref. When
1458  * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1459  * will be released and @mstb may no longer be used.
1460  *
1461  * See also: drm_dp_mst_get_mstb_malloc()
1462  */
1463 static void
1464 drm_dp_mst_put_mstb_malloc(struct drm_dp_mst_branch *mstb)
1465 {
1466 	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref) - 1);
1467 	kref_put(&mstb->malloc_kref, drm_dp_free_mst_branch_device);
1468 }
1469 
1470 static void drm_dp_free_mst_port(struct kref *kref)
1471 {
1472 	struct drm_dp_mst_port *port =
1473 		container_of(kref, struct drm_dp_mst_port, malloc_kref);
1474 
1475 	drm_dp_mst_put_mstb_malloc(port->parent);
1476 	kfree(port);
1477 }
1478 
1479 /**
1480  * drm_dp_mst_get_port_malloc() - Increment the malloc refcount of an MST port
1481  * @port: The &struct drm_dp_mst_port to increment the malloc refcount of
1482  *
1483  * Increments &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1484  * reaches 0, the memory allocation for @port will be released and @port may
1485  * no longer be used.
1486  *
1487  * Because @port could potentially be freed at any time by the DP MST helpers
1488  * if &drm_dp_mst_port.malloc_kref reaches 0, including during a call to this
1489  * function, drivers that which to make use of &struct drm_dp_mst_port should
1490  * ensure that they grab at least one main malloc reference to their MST ports
1491  * in &drm_dp_mst_topology_cbs.add_connector. This callback is called before
1492  * there is any chance for &drm_dp_mst_port.malloc_kref to reach 0.
1493  *
1494  * See also: drm_dp_mst_put_port_malloc()
1495  */
1496 void
1497 drm_dp_mst_get_port_malloc(struct drm_dp_mst_port *port)
1498 {
1499 	kref_get(&port->malloc_kref);
1500 	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->malloc_kref));
1501 }
1502 EXPORT_SYMBOL(drm_dp_mst_get_port_malloc);
1503 
1504 /**
1505  * drm_dp_mst_put_port_malloc() - Decrement the malloc refcount of an MST port
1506  * @port: The &struct drm_dp_mst_port to decrement the malloc refcount of
1507  *
1508  * Decrements &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1509  * reaches 0, the memory allocation for @port will be released and @port may
1510  * no longer be used.
1511  *
1512  * See also: drm_dp_mst_get_port_malloc()
1513  */
1514 void
1515 drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port)
1516 {
1517 	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->malloc_kref) - 1);
1518 	kref_put(&port->malloc_kref, drm_dp_free_mst_port);
1519 }
1520 EXPORT_SYMBOL(drm_dp_mst_put_port_malloc);
1521 
1522 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
1523 
1524 #define STACK_DEPTH 8
1525 
1526 static noinline void
1527 __topology_ref_save(struct drm_dp_mst_topology_mgr *mgr,
1528 		    struct drm_dp_mst_topology_ref_history *history,
1529 		    enum drm_dp_mst_topology_ref_type type)
1530 {
1531 	struct drm_dp_mst_topology_ref_entry *entry = NULL;
1532 	depot_stack_handle_t backtrace;
1533 	ulong stack_entries[STACK_DEPTH];
1534 	uint n;
1535 	int i;
1536 
1537 	n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1);
1538 	backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL);
1539 	if (!backtrace)
1540 		return;
1541 
1542 	/* Try to find an existing entry for this backtrace */
1543 	for (i = 0; i < history->len; i++) {
1544 		if (history->entries[i].backtrace == backtrace) {
1545 			entry = &history->entries[i];
1546 			break;
1547 		}
1548 	}
1549 
1550 	/* Otherwise add one */
1551 	if (!entry) {
1552 		struct drm_dp_mst_topology_ref_entry *new;
1553 		int new_len = history->len + 1;
1554 
1555 		new = krealloc(history->entries, sizeof(*new) * new_len,
1556 			       GFP_KERNEL);
1557 		if (!new)
1558 			return;
1559 
1560 		entry = &new[history->len];
1561 		history->len = new_len;
1562 		history->entries = new;
1563 
1564 		entry->backtrace = backtrace;
1565 		entry->type = type;
1566 		entry->count = 0;
1567 	}
1568 	entry->count++;
1569 	entry->ts_nsec = ktime_get_ns();
1570 }
1571 
1572 static int
1573 topology_ref_history_cmp(const void *a, const void *b)
1574 {
1575 	const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b;
1576 
1577 	if (entry_a->ts_nsec > entry_b->ts_nsec)
1578 		return 1;
1579 	else if (entry_a->ts_nsec < entry_b->ts_nsec)
1580 		return -1;
1581 	else
1582 		return 0;
1583 }
1584 
1585 static inline const char *
1586 topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type)
1587 {
1588 	if (type == DRM_DP_MST_TOPOLOGY_REF_GET)
1589 		return "get";
1590 	else
1591 		return "put";
1592 }
1593 
1594 static void
1595 __dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history,
1596 			    void *ptr, const char *type_str)
1597 {
1598 	struct drm_printer p = drm_debug_printer(DBG_PREFIX);
1599 	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
1600 	int i;
1601 
1602 	if (!buf)
1603 		return;
1604 
1605 	if (!history->len)
1606 		goto out;
1607 
1608 	/* First, sort the list so that it goes from oldest to newest
1609 	 * reference entry
1610 	 */
1611 	sort(history->entries, history->len, sizeof(*history->entries),
1612 	     topology_ref_history_cmp, NULL);
1613 
1614 	drm_printf(&p, "%s (%p) topology count reached 0, dumping history:\n",
1615 		   type_str, ptr);
1616 
1617 	for (i = 0; i < history->len; i++) {
1618 		const struct drm_dp_mst_topology_ref_entry *entry =
1619 			&history->entries[i];
1620 		u64 ts_nsec = entry->ts_nsec;
1621 		u32 rem_nsec = do_div(ts_nsec, 1000000000);
1622 
1623 		stack_depot_snprint(entry->backtrace, buf, PAGE_SIZE, 4);
1624 
1625 		drm_printf(&p, "  %d %ss (last at %5llu.%06u):\n%s",
1626 			   entry->count,
1627 			   topology_ref_type_to_str(entry->type),
1628 			   ts_nsec, rem_nsec / 1000, buf);
1629 	}
1630 
1631 	/* Now free the history, since this is the only time we expose it */
1632 	kfree(history->entries);
1633 out:
1634 	kfree(buf);
1635 }
1636 
1637 static __always_inline void
1638 drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb)
1639 {
1640 	__dump_topology_ref_history(&mstb->topology_ref_history, mstb,
1641 				    "MSTB");
1642 }
1643 
1644 static __always_inline void
1645 drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port)
1646 {
1647 	__dump_topology_ref_history(&port->topology_ref_history, port,
1648 				    "Port");
1649 }
1650 
1651 static __always_inline void
1652 save_mstb_topology_ref(struct drm_dp_mst_branch *mstb,
1653 		       enum drm_dp_mst_topology_ref_type type)
1654 {
1655 	__topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type);
1656 }
1657 
1658 static __always_inline void
1659 save_port_topology_ref(struct drm_dp_mst_port *port,
1660 		       enum drm_dp_mst_topology_ref_type type)
1661 {
1662 	__topology_ref_save(port->mgr, &port->topology_ref_history, type);
1663 }
1664 
1665 static inline void
1666 topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr)
1667 {
1668 	mutex_lock(&mgr->topology_ref_history_lock);
1669 }
1670 
1671 static inline void
1672 topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr)
1673 {
1674 	mutex_unlock(&mgr->topology_ref_history_lock);
1675 }
1676 #else
1677 static inline void
1678 topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {}
1679 static inline void
1680 topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {}
1681 static inline void
1682 drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {}
1683 static inline void
1684 drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {}
1685 #define save_mstb_topology_ref(mstb, type)
1686 #define save_port_topology_ref(port, type)
1687 #endif
1688 
1689 struct drm_dp_mst_atomic_payload *
1690 drm_atomic_get_mst_payload_state(struct drm_dp_mst_topology_state *state,
1691 				 struct drm_dp_mst_port *port)
1692 {
1693 	struct drm_dp_mst_atomic_payload *payload;
1694 
1695 	list_for_each_entry(payload, &state->payloads, next)
1696 		if (payload->port == port)
1697 			return payload;
1698 
1699 	return NULL;
1700 }
1701 EXPORT_SYMBOL(drm_atomic_get_mst_payload_state);
1702 
1703 static void drm_dp_destroy_mst_branch_device(struct kref *kref)
1704 {
1705 	struct drm_dp_mst_branch *mstb =
1706 		container_of(kref, struct drm_dp_mst_branch, topology_kref);
1707 	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1708 
1709 	drm_dp_mst_dump_mstb_topology_history(mstb);
1710 
1711 	INIT_LIST_HEAD(&mstb->destroy_next);
1712 
1713 	/*
1714 	 * This can get called under mgr->mutex, so we need to perform the
1715 	 * actual destruction of the mstb in another worker
1716 	 */
1717 	mutex_lock(&mgr->delayed_destroy_lock);
1718 	list_add(&mstb->destroy_next, &mgr->destroy_branch_device_list);
1719 	mutex_unlock(&mgr->delayed_destroy_lock);
1720 	queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
1721 }
1722 
1723 /**
1724  * drm_dp_mst_topology_try_get_mstb() - Increment the topology refcount of a
1725  * branch device unless it's zero
1726  * @mstb: &struct drm_dp_mst_branch to increment the topology refcount of
1727  *
1728  * Attempts to grab a topology reference to @mstb, if it hasn't yet been
1729  * removed from the topology (e.g. &drm_dp_mst_branch.topology_kref has
1730  * reached 0). Holding a topology reference implies that a malloc reference
1731  * will be held to @mstb as long as the user holds the topology reference.
1732  *
1733  * Care should be taken to ensure that the user has at least one malloc
1734  * reference to @mstb. If you already have a topology reference to @mstb, you
1735  * should use drm_dp_mst_topology_get_mstb() instead.
1736  *
1737  * See also:
1738  * drm_dp_mst_topology_get_mstb()
1739  * drm_dp_mst_topology_put_mstb()
1740  *
1741  * Returns:
1742  * * 1: A topology reference was grabbed successfully
1743  * * 0: @port is no longer in the topology, no reference was grabbed
1744  */
1745 static int __must_check
1746 drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb)
1747 {
1748 	int ret;
1749 
1750 	topology_ref_history_lock(mstb->mgr);
1751 	ret = kref_get_unless_zero(&mstb->topology_kref);
1752 	if (ret) {
1753 		drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
1754 		save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
1755 	}
1756 
1757 	topology_ref_history_unlock(mstb->mgr);
1758 
1759 	return ret;
1760 }
1761 
1762 /**
1763  * drm_dp_mst_topology_get_mstb() - Increment the topology refcount of a
1764  * branch device
1765  * @mstb: The &struct drm_dp_mst_branch to increment the topology refcount of
1766  *
1767  * Increments &drm_dp_mst_branch.topology_refcount without checking whether or
1768  * not it's already reached 0. This is only valid to use in scenarios where
1769  * you are already guaranteed to have at least one active topology reference
1770  * to @mstb. Otherwise, drm_dp_mst_topology_try_get_mstb() must be used.
1771  *
1772  * See also:
1773  * drm_dp_mst_topology_try_get_mstb()
1774  * drm_dp_mst_topology_put_mstb()
1775  */
1776 static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb)
1777 {
1778 	topology_ref_history_lock(mstb->mgr);
1779 
1780 	save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
1781 	WARN_ON(kref_read(&mstb->topology_kref) == 0);
1782 	kref_get(&mstb->topology_kref);
1783 	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
1784 
1785 	topology_ref_history_unlock(mstb->mgr);
1786 }
1787 
1788 /**
1789  * drm_dp_mst_topology_put_mstb() - release a topology reference to a branch
1790  * device
1791  * @mstb: The &struct drm_dp_mst_branch to release the topology reference from
1792  *
1793  * Releases a topology reference from @mstb by decrementing
1794  * &drm_dp_mst_branch.topology_kref.
1795  *
1796  * See also:
1797  * drm_dp_mst_topology_try_get_mstb()
1798  * drm_dp_mst_topology_get_mstb()
1799  */
1800 static void
1801 drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb)
1802 {
1803 	topology_ref_history_lock(mstb->mgr);
1804 
1805 	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref) - 1);
1806 	save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT);
1807 
1808 	topology_ref_history_unlock(mstb->mgr);
1809 	kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device);
1810 }
1811 
1812 static void drm_dp_destroy_port(struct kref *kref)
1813 {
1814 	struct drm_dp_mst_port *port =
1815 		container_of(kref, struct drm_dp_mst_port, topology_kref);
1816 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
1817 
1818 	drm_dp_mst_dump_port_topology_history(port);
1819 
1820 	/* There's nothing that needs locking to destroy an input port yet */
1821 	if (port->input) {
1822 		drm_dp_mst_put_port_malloc(port);
1823 		return;
1824 	}
1825 
1826 	kfree(port->cached_edid);
1827 
1828 	/*
1829 	 * we can't destroy the connector here, as we might be holding the
1830 	 * mode_config.mutex from an EDID retrieval
1831 	 */
1832 	mutex_lock(&mgr->delayed_destroy_lock);
1833 	list_add(&port->next, &mgr->destroy_port_list);
1834 	mutex_unlock(&mgr->delayed_destroy_lock);
1835 	queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
1836 }
1837 
1838 /**
1839  * drm_dp_mst_topology_try_get_port() - Increment the topology refcount of a
1840  * port unless it's zero
1841  * @port: &struct drm_dp_mst_port to increment the topology refcount of
1842  *
1843  * Attempts to grab a topology reference to @port, if it hasn't yet been
1844  * removed from the topology (e.g. &drm_dp_mst_port.topology_kref has reached
1845  * 0). Holding a topology reference implies that a malloc reference will be
1846  * held to @port as long as the user holds the topology reference.
1847  *
1848  * Care should be taken to ensure that the user has at least one malloc
1849  * reference to @port. If you already have a topology reference to @port, you
1850  * should use drm_dp_mst_topology_get_port() instead.
1851  *
1852  * See also:
1853  * drm_dp_mst_topology_get_port()
1854  * drm_dp_mst_topology_put_port()
1855  *
1856  * Returns:
1857  * * 1: A topology reference was grabbed successfully
1858  * * 0: @port is no longer in the topology, no reference was grabbed
1859  */
1860 static int __must_check
1861 drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port)
1862 {
1863 	int ret;
1864 
1865 	topology_ref_history_lock(port->mgr);
1866 	ret = kref_get_unless_zero(&port->topology_kref);
1867 	if (ret) {
1868 		drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref));
1869 		save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
1870 	}
1871 
1872 	topology_ref_history_unlock(port->mgr);
1873 	return ret;
1874 }
1875 
1876 /**
1877  * drm_dp_mst_topology_get_port() - Increment the topology refcount of a port
1878  * @port: The &struct drm_dp_mst_port to increment the topology refcount of
1879  *
1880  * Increments &drm_dp_mst_port.topology_refcount without checking whether or
1881  * not it's already reached 0. This is only valid to use in scenarios where
1882  * you are already guaranteed to have at least one active topology reference
1883  * to @port. Otherwise, drm_dp_mst_topology_try_get_port() must be used.
1884  *
1885  * See also:
1886  * drm_dp_mst_topology_try_get_port()
1887  * drm_dp_mst_topology_put_port()
1888  */
1889 static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
1890 {
1891 	topology_ref_history_lock(port->mgr);
1892 
1893 	WARN_ON(kref_read(&port->topology_kref) == 0);
1894 	kref_get(&port->topology_kref);
1895 	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref));
1896 	save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
1897 
1898 	topology_ref_history_unlock(port->mgr);
1899 }
1900 
1901 /**
1902  * drm_dp_mst_topology_put_port() - release a topology reference to a port
1903  * @port: The &struct drm_dp_mst_port to release the topology reference from
1904  *
1905  * Releases a topology reference from @port by decrementing
1906  * &drm_dp_mst_port.topology_kref.
1907  *
1908  * See also:
1909  * drm_dp_mst_topology_try_get_port()
1910  * drm_dp_mst_topology_get_port()
1911  */
1912 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
1913 {
1914 	topology_ref_history_lock(port->mgr);
1915 
1916 	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref) - 1);
1917 	save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT);
1918 
1919 	topology_ref_history_unlock(port->mgr);
1920 	kref_put(&port->topology_kref, drm_dp_destroy_port);
1921 }
1922 
1923 static struct drm_dp_mst_branch *
1924 drm_dp_mst_topology_get_mstb_validated_locked(struct drm_dp_mst_branch *mstb,
1925 					      struct drm_dp_mst_branch *to_find)
1926 {
1927 	struct drm_dp_mst_port *port;
1928 	struct drm_dp_mst_branch *rmstb;
1929 
1930 	if (to_find == mstb)
1931 		return mstb;
1932 
1933 	list_for_each_entry(port, &mstb->ports, next) {
1934 		if (port->mstb) {
1935 			rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1936 			    port->mstb, to_find);
1937 			if (rmstb)
1938 				return rmstb;
1939 		}
1940 	}
1941 	return NULL;
1942 }
1943 
1944 static struct drm_dp_mst_branch *
1945 drm_dp_mst_topology_get_mstb_validated(struct drm_dp_mst_topology_mgr *mgr,
1946 				       struct drm_dp_mst_branch *mstb)
1947 {
1948 	struct drm_dp_mst_branch *rmstb = NULL;
1949 
1950 	mutex_lock(&mgr->lock);
1951 	if (mgr->mst_primary) {
1952 		rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1953 		    mgr->mst_primary, mstb);
1954 
1955 		if (rmstb && !drm_dp_mst_topology_try_get_mstb(rmstb))
1956 			rmstb = NULL;
1957 	}
1958 	mutex_unlock(&mgr->lock);
1959 	return rmstb;
1960 }
1961 
1962 static struct drm_dp_mst_port *
1963 drm_dp_mst_topology_get_port_validated_locked(struct drm_dp_mst_branch *mstb,
1964 					      struct drm_dp_mst_port *to_find)
1965 {
1966 	struct drm_dp_mst_port *port, *mport;
1967 
1968 	list_for_each_entry(port, &mstb->ports, next) {
1969 		if (port == to_find)
1970 			return port;
1971 
1972 		if (port->mstb) {
1973 			mport = drm_dp_mst_topology_get_port_validated_locked(
1974 			    port->mstb, to_find);
1975 			if (mport)
1976 				return mport;
1977 		}
1978 	}
1979 	return NULL;
1980 }
1981 
1982 static struct drm_dp_mst_port *
1983 drm_dp_mst_topology_get_port_validated(struct drm_dp_mst_topology_mgr *mgr,
1984 				       struct drm_dp_mst_port *port)
1985 {
1986 	struct drm_dp_mst_port *rport = NULL;
1987 
1988 	mutex_lock(&mgr->lock);
1989 	if (mgr->mst_primary) {
1990 		rport = drm_dp_mst_topology_get_port_validated_locked(
1991 		    mgr->mst_primary, port);
1992 
1993 		if (rport && !drm_dp_mst_topology_try_get_port(rport))
1994 			rport = NULL;
1995 	}
1996 	mutex_unlock(&mgr->lock);
1997 	return rport;
1998 }
1999 
2000 static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u8 port_num)
2001 {
2002 	struct drm_dp_mst_port *port;
2003 	int ret;
2004 
2005 	list_for_each_entry(port, &mstb->ports, next) {
2006 		if (port->port_num == port_num) {
2007 			ret = drm_dp_mst_topology_try_get_port(port);
2008 			return ret ? port : NULL;
2009 		}
2010 	}
2011 
2012 	return NULL;
2013 }
2014 
2015 /*
2016  * calculate a new RAD for this MST branch device
2017  * if parent has an LCT of 2 then it has 1 nibble of RAD,
2018  * if parent has an LCT of 3 then it has 2 nibbles of RAD,
2019  */
2020 static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
2021 				 u8 *rad)
2022 {
2023 	int parent_lct = port->parent->lct;
2024 	int shift = 4;
2025 	int idx = (parent_lct - 1) / 2;
2026 
2027 	if (parent_lct > 1) {
2028 		memcpy(rad, port->parent->rad, idx + 1);
2029 		shift = (parent_lct % 2) ? 4 : 0;
2030 	} else
2031 		rad[0] = 0;
2032 
2033 	rad[idx] |= port->port_num << shift;
2034 	return parent_lct + 1;
2035 }
2036 
2037 static bool drm_dp_mst_is_end_device(u8 pdt, bool mcs)
2038 {
2039 	switch (pdt) {
2040 	case DP_PEER_DEVICE_DP_LEGACY_CONV:
2041 	case DP_PEER_DEVICE_SST_SINK:
2042 		return true;
2043 	case DP_PEER_DEVICE_MST_BRANCHING:
2044 		/* For sst branch device */
2045 		if (!mcs)
2046 			return true;
2047 
2048 		return false;
2049 	}
2050 	return true;
2051 }
2052 
2053 static int
2054 drm_dp_port_set_pdt(struct drm_dp_mst_port *port, u8 new_pdt,
2055 		    bool new_mcs)
2056 {
2057 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
2058 	struct drm_dp_mst_branch *mstb;
2059 	u8 rad[8], lct;
2060 	int ret = 0;
2061 
2062 	if (port->pdt == new_pdt && port->mcs == new_mcs)
2063 		return 0;
2064 
2065 	/* Teardown the old pdt, if there is one */
2066 	if (port->pdt != DP_PEER_DEVICE_NONE) {
2067 		if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
2068 			/*
2069 			 * If the new PDT would also have an i2c bus,
2070 			 * don't bother with reregistering it
2071 			 */
2072 			if (new_pdt != DP_PEER_DEVICE_NONE &&
2073 			    drm_dp_mst_is_end_device(new_pdt, new_mcs)) {
2074 				port->pdt = new_pdt;
2075 				port->mcs = new_mcs;
2076 				return 0;
2077 			}
2078 
2079 			/* remove i2c over sideband */
2080 			drm_dp_mst_unregister_i2c_bus(port);
2081 		} else {
2082 			mutex_lock(&mgr->lock);
2083 			drm_dp_mst_topology_put_mstb(port->mstb);
2084 			port->mstb = NULL;
2085 			mutex_unlock(&mgr->lock);
2086 		}
2087 	}
2088 
2089 	port->pdt = new_pdt;
2090 	port->mcs = new_mcs;
2091 
2092 	if (port->pdt != DP_PEER_DEVICE_NONE) {
2093 		if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
2094 			/* add i2c over sideband */
2095 			ret = drm_dp_mst_register_i2c_bus(port);
2096 		} else {
2097 			lct = drm_dp_calculate_rad(port, rad);
2098 			mstb = drm_dp_add_mst_branch_device(lct, rad);
2099 			if (!mstb) {
2100 				ret = -ENOMEM;
2101 				drm_err(mgr->dev, "Failed to create MSTB for port %p", port);
2102 				goto out;
2103 			}
2104 
2105 			mutex_lock(&mgr->lock);
2106 			port->mstb = mstb;
2107 			mstb->mgr = port->mgr;
2108 			mstb->port_parent = port;
2109 
2110 			/*
2111 			 * Make sure this port's memory allocation stays
2112 			 * around until its child MSTB releases it
2113 			 */
2114 			drm_dp_mst_get_port_malloc(port);
2115 			mutex_unlock(&mgr->lock);
2116 
2117 			/* And make sure we send a link address for this */
2118 			ret = 1;
2119 		}
2120 	}
2121 
2122 out:
2123 	if (ret < 0)
2124 		port->pdt = DP_PEER_DEVICE_NONE;
2125 	return ret;
2126 }
2127 
2128 /**
2129  * drm_dp_mst_dpcd_read() - read a series of bytes from the DPCD via sideband
2130  * @aux: Fake sideband AUX CH
2131  * @offset: address of the (first) register to read
2132  * @buffer: buffer to store the register values
2133  * @size: number of bytes in @buffer
2134  *
2135  * Performs the same functionality for remote devices via
2136  * sideband messaging as drm_dp_dpcd_read() does for local
2137  * devices via actual AUX CH.
2138  *
2139  * Return: Number of bytes read, or negative error code on failure.
2140  */
2141 ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
2142 			     unsigned int offset, void *buffer, size_t size)
2143 {
2144 	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
2145 						    aux);
2146 
2147 	return drm_dp_send_dpcd_read(port->mgr, port,
2148 				     offset, size, buffer);
2149 }
2150 
2151 /**
2152  * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via sideband
2153  * @aux: Fake sideband AUX CH
2154  * @offset: address of the (first) register to write
2155  * @buffer: buffer containing the values to write
2156  * @size: number of bytes in @buffer
2157  *
2158  * Performs the same functionality for remote devices via
2159  * sideband messaging as drm_dp_dpcd_write() does for local
2160  * devices via actual AUX CH.
2161  *
2162  * Return: number of bytes written on success, negative error code on failure.
2163  */
2164 ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
2165 			      unsigned int offset, void *buffer, size_t size)
2166 {
2167 	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
2168 						    aux);
2169 
2170 	return drm_dp_send_dpcd_write(port->mgr, port,
2171 				      offset, size, buffer);
2172 }
2173 
2174 static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
2175 {
2176 	int ret = 0;
2177 
2178 	memcpy(mstb->guid, guid, 16);
2179 
2180 	if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) {
2181 		if (mstb->port_parent) {
2182 			ret = drm_dp_send_dpcd_write(mstb->mgr,
2183 						     mstb->port_parent,
2184 						     DP_GUID, 16, mstb->guid);
2185 		} else {
2186 			ret = drm_dp_dpcd_write(mstb->mgr->aux,
2187 						DP_GUID, mstb->guid, 16);
2188 		}
2189 	}
2190 
2191 	if (ret < 16 && ret > 0)
2192 		return -EPROTO;
2193 
2194 	return ret == 16 ? 0 : ret;
2195 }
2196 
2197 static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
2198 				int pnum,
2199 				char *proppath,
2200 				size_t proppath_size)
2201 {
2202 	int i;
2203 	char temp[8];
2204 
2205 	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
2206 	for (i = 0; i < (mstb->lct - 1); i++) {
2207 		int shift = (i % 2) ? 0 : 4;
2208 		int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
2209 
2210 		snprintf(temp, sizeof(temp), "-%d", port_num);
2211 		strlcat(proppath, temp, proppath_size);
2212 	}
2213 	snprintf(temp, sizeof(temp), "-%d", pnum);
2214 	strlcat(proppath, temp, proppath_size);
2215 }
2216 
2217 /**
2218  * drm_dp_mst_connector_late_register() - Late MST connector registration
2219  * @connector: The MST connector
2220  * @port: The MST port for this connector
2221  *
2222  * Helper to register the remote aux device for this MST port. Drivers should
2223  * call this from their mst connector's late_register hook to enable MST aux
2224  * devices.
2225  *
2226  * Return: 0 on success, negative error code on failure.
2227  */
2228 int drm_dp_mst_connector_late_register(struct drm_connector *connector,
2229 				       struct drm_dp_mst_port *port)
2230 {
2231 	drm_dbg_kms(port->mgr->dev, "registering %s remote bus for %s\n",
2232 		    port->aux.name, connector->kdev->kobj.name);
2233 
2234 	port->aux.dev = connector->kdev;
2235 	return drm_dp_aux_register_devnode(&port->aux);
2236 }
2237 EXPORT_SYMBOL(drm_dp_mst_connector_late_register);
2238 
2239 /**
2240  * drm_dp_mst_connector_early_unregister() - Early MST connector unregistration
2241  * @connector: The MST connector
2242  * @port: The MST port for this connector
2243  *
2244  * Helper to unregister the remote aux device for this MST port, registered by
2245  * drm_dp_mst_connector_late_register(). Drivers should call this from their mst
2246  * connector's early_unregister hook.
2247  */
2248 void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
2249 					   struct drm_dp_mst_port *port)
2250 {
2251 	drm_dbg_kms(port->mgr->dev, "unregistering %s remote bus for %s\n",
2252 		    port->aux.name, connector->kdev->kobj.name);
2253 	drm_dp_aux_unregister_devnode(&port->aux);
2254 }
2255 EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
2256 
2257 static void
2258 drm_dp_mst_port_add_connector(struct drm_dp_mst_branch *mstb,
2259 			      struct drm_dp_mst_port *port)
2260 {
2261 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
2262 	char proppath[255];
2263 	int ret;
2264 
2265 	build_mst_prop_path(mstb, port->port_num, proppath, sizeof(proppath));
2266 	port->connector = mgr->cbs->add_connector(mgr, port, proppath);
2267 	if (!port->connector) {
2268 		ret = -ENOMEM;
2269 		goto error;
2270 	}
2271 
2272 	if (port->pdt != DP_PEER_DEVICE_NONE &&
2273 	    drm_dp_mst_is_end_device(port->pdt, port->mcs) &&
2274 	    port->port_num >= DP_MST_LOGICAL_PORT_0)
2275 		port->cached_edid = drm_get_edid(port->connector,
2276 						 &port->aux.ddc);
2277 
2278 	drm_connector_register(port->connector);
2279 	return;
2280 
2281 error:
2282 	drm_err(mgr->dev, "Failed to create connector for port %p: %d\n", port, ret);
2283 }
2284 
2285 /*
2286  * Drop a topology reference, and unlink the port from the in-memory topology
2287  * layout
2288  */
2289 static void
2290 drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
2291 				struct drm_dp_mst_port *port)
2292 {
2293 	mutex_lock(&mgr->lock);
2294 	port->parent->num_ports--;
2295 	list_del(&port->next);
2296 	mutex_unlock(&mgr->lock);
2297 	drm_dp_mst_topology_put_port(port);
2298 }
2299 
2300 static struct drm_dp_mst_port *
2301 drm_dp_mst_add_port(struct drm_device *dev,
2302 		    struct drm_dp_mst_topology_mgr *mgr,
2303 		    struct drm_dp_mst_branch *mstb, u8 port_number)
2304 {
2305 	struct drm_dp_mst_port *port = kzalloc(sizeof(*port), GFP_KERNEL);
2306 
2307 	if (!port)
2308 		return NULL;
2309 
2310 	kref_init(&port->topology_kref);
2311 	kref_init(&port->malloc_kref);
2312 	port->parent = mstb;
2313 	port->port_num = port_number;
2314 	port->mgr = mgr;
2315 	port->aux.name = "DPMST";
2316 	port->aux.dev = dev->dev;
2317 	port->aux.is_remote = true;
2318 
2319 	/* initialize the MST downstream port's AUX crc work queue */
2320 	port->aux.drm_dev = dev;
2321 	drm_dp_remote_aux_init(&port->aux);
2322 
2323 	/*
2324 	 * Make sure the memory allocation for our parent branch stays
2325 	 * around until our own memory allocation is released
2326 	 */
2327 	drm_dp_mst_get_mstb_malloc(mstb);
2328 
2329 	return port;
2330 }
2331 
2332 static int
2333 drm_dp_mst_handle_link_address_port(struct drm_dp_mst_branch *mstb,
2334 				    struct drm_device *dev,
2335 				    struct drm_dp_link_addr_reply_port *port_msg)
2336 {
2337 	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
2338 	struct drm_dp_mst_port *port;
2339 	int old_ddps = 0, ret;
2340 	u8 new_pdt = DP_PEER_DEVICE_NONE;
2341 	bool new_mcs = 0;
2342 	bool created = false, send_link_addr = false, changed = false;
2343 
2344 	port = drm_dp_get_port(mstb, port_msg->port_number);
2345 	if (!port) {
2346 		port = drm_dp_mst_add_port(dev, mgr, mstb,
2347 					   port_msg->port_number);
2348 		if (!port)
2349 			return -ENOMEM;
2350 		created = true;
2351 		changed = true;
2352 	} else if (!port->input && port_msg->input_port && port->connector) {
2353 		/* Since port->connector can't be changed here, we create a
2354 		 * new port if input_port changes from 0 to 1
2355 		 */
2356 		drm_dp_mst_topology_unlink_port(mgr, port);
2357 		drm_dp_mst_topology_put_port(port);
2358 		port = drm_dp_mst_add_port(dev, mgr, mstb,
2359 					   port_msg->port_number);
2360 		if (!port)
2361 			return -ENOMEM;
2362 		changed = true;
2363 		created = true;
2364 	} else if (port->input && !port_msg->input_port) {
2365 		changed = true;
2366 	} else if (port->connector) {
2367 		/* We're updating a port that's exposed to userspace, so do it
2368 		 * under lock
2369 		 */
2370 		drm_modeset_lock(&mgr->base.lock, NULL);
2371 
2372 		old_ddps = port->ddps;
2373 		changed = port->ddps != port_msg->ddps ||
2374 			(port->ddps &&
2375 			 (port->ldps != port_msg->legacy_device_plug_status ||
2376 			  port->dpcd_rev != port_msg->dpcd_revision ||
2377 			  port->mcs != port_msg->mcs ||
2378 			  port->pdt != port_msg->peer_device_type ||
2379 			  port->num_sdp_stream_sinks !=
2380 			  port_msg->num_sdp_stream_sinks));
2381 	}
2382 
2383 	port->input = port_msg->input_port;
2384 	if (!port->input)
2385 		new_pdt = port_msg->peer_device_type;
2386 	new_mcs = port_msg->mcs;
2387 	port->ddps = port_msg->ddps;
2388 	port->ldps = port_msg->legacy_device_plug_status;
2389 	port->dpcd_rev = port_msg->dpcd_revision;
2390 	port->num_sdp_streams = port_msg->num_sdp_streams;
2391 	port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
2392 
2393 	/* manage mstb port lists with mgr lock - take a reference
2394 	   for this list */
2395 	if (created) {
2396 		mutex_lock(&mgr->lock);
2397 		drm_dp_mst_topology_get_port(port);
2398 		list_add(&port->next, &mstb->ports);
2399 		mstb->num_ports++;
2400 		mutex_unlock(&mgr->lock);
2401 	}
2402 
2403 	/*
2404 	 * Reprobe PBN caps on both hotplug, and when re-probing the link
2405 	 * for our parent mstb
2406 	 */
2407 	if (old_ddps != port->ddps || !created) {
2408 		if (port->ddps && !port->input) {
2409 			ret = drm_dp_send_enum_path_resources(mgr, mstb,
2410 							      port);
2411 			if (ret == 1)
2412 				changed = true;
2413 		} else {
2414 			port->full_pbn = 0;
2415 		}
2416 	}
2417 
2418 	ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
2419 	if (ret == 1) {
2420 		send_link_addr = true;
2421 	} else if (ret < 0) {
2422 		drm_err(dev, "Failed to change PDT on port %p: %d\n", port, ret);
2423 		goto fail;
2424 	}
2425 
2426 	/*
2427 	 * If this port wasn't just created, then we're reprobing because
2428 	 * we're coming out of suspend. In this case, always resend the link
2429 	 * address if there's an MSTB on this port
2430 	 */
2431 	if (!created && port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
2432 	    port->mcs)
2433 		send_link_addr = true;
2434 
2435 	if (port->connector)
2436 		drm_modeset_unlock(&mgr->base.lock);
2437 	else if (!port->input)
2438 		drm_dp_mst_port_add_connector(mstb, port);
2439 
2440 	if (send_link_addr && port->mstb) {
2441 		ret = drm_dp_send_link_address(mgr, port->mstb);
2442 		if (ret == 1) /* MSTB below us changed */
2443 			changed = true;
2444 		else if (ret < 0)
2445 			goto fail_put;
2446 	}
2447 
2448 	/* put reference to this port */
2449 	drm_dp_mst_topology_put_port(port);
2450 	return changed;
2451 
2452 fail:
2453 	drm_dp_mst_topology_unlink_port(mgr, port);
2454 	if (port->connector)
2455 		drm_modeset_unlock(&mgr->base.lock);
2456 fail_put:
2457 	drm_dp_mst_topology_put_port(port);
2458 	return ret;
2459 }
2460 
2461 static int
2462 drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
2463 			    struct drm_dp_connection_status_notify *conn_stat)
2464 {
2465 	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
2466 	struct drm_dp_mst_port *port;
2467 	int old_ddps, ret;
2468 	u8 new_pdt;
2469 	bool new_mcs;
2470 	bool dowork = false, create_connector = false;
2471 
2472 	port = drm_dp_get_port(mstb, conn_stat->port_number);
2473 	if (!port)
2474 		return 0;
2475 
2476 	if (port->connector) {
2477 		if (!port->input && conn_stat->input_port) {
2478 			/*
2479 			 * We can't remove a connector from an already exposed
2480 			 * port, so just throw the port out and make sure we
2481 			 * reprobe the link address of it's parent MSTB
2482 			 */
2483 			drm_dp_mst_topology_unlink_port(mgr, port);
2484 			mstb->link_address_sent = false;
2485 			dowork = true;
2486 			goto out;
2487 		}
2488 
2489 		/* Locking is only needed if the port's exposed to userspace */
2490 		drm_modeset_lock(&mgr->base.lock, NULL);
2491 	} else if (port->input && !conn_stat->input_port) {
2492 		create_connector = true;
2493 		/* Reprobe link address so we get num_sdp_streams */
2494 		mstb->link_address_sent = false;
2495 		dowork = true;
2496 	}
2497 
2498 	old_ddps = port->ddps;
2499 	port->input = conn_stat->input_port;
2500 	port->ldps = conn_stat->legacy_device_plug_status;
2501 	port->ddps = conn_stat->displayport_device_plug_status;
2502 
2503 	if (old_ddps != port->ddps) {
2504 		if (port->ddps && !port->input)
2505 			drm_dp_send_enum_path_resources(mgr, mstb, port);
2506 		else
2507 			port->full_pbn = 0;
2508 	}
2509 
2510 	new_pdt = port->input ? DP_PEER_DEVICE_NONE : conn_stat->peer_device_type;
2511 	new_mcs = conn_stat->message_capability_status;
2512 	ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
2513 	if (ret == 1) {
2514 		dowork = true;
2515 	} else if (ret < 0) {
2516 		drm_err(mgr->dev, "Failed to change PDT for port %p: %d\n", port, ret);
2517 		dowork = false;
2518 	}
2519 
2520 	if (port->connector)
2521 		drm_modeset_unlock(&mgr->base.lock);
2522 	else if (create_connector)
2523 		drm_dp_mst_port_add_connector(mstb, port);
2524 
2525 out:
2526 	drm_dp_mst_topology_put_port(port);
2527 	return dowork;
2528 }
2529 
2530 static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
2531 							       u8 lct, u8 *rad)
2532 {
2533 	struct drm_dp_mst_branch *mstb;
2534 	struct drm_dp_mst_port *port;
2535 	int i, ret;
2536 	/* find the port by iterating down */
2537 
2538 	mutex_lock(&mgr->lock);
2539 	mstb = mgr->mst_primary;
2540 
2541 	if (!mstb)
2542 		goto out;
2543 
2544 	for (i = 0; i < lct - 1; i++) {
2545 		int shift = (i % 2) ? 0 : 4;
2546 		int port_num = (rad[i / 2] >> shift) & 0xf;
2547 
2548 		list_for_each_entry(port, &mstb->ports, next) {
2549 			if (port->port_num == port_num) {
2550 				mstb = port->mstb;
2551 				if (!mstb) {
2552 					drm_err(mgr->dev,
2553 						"failed to lookup MSTB with lct %d, rad %02x\n",
2554 						lct, rad[0]);
2555 					goto out;
2556 				}
2557 
2558 				break;
2559 			}
2560 		}
2561 	}
2562 	ret = drm_dp_mst_topology_try_get_mstb(mstb);
2563 	if (!ret)
2564 		mstb = NULL;
2565 out:
2566 	mutex_unlock(&mgr->lock);
2567 	return mstb;
2568 }
2569 
2570 static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
2571 	struct drm_dp_mst_branch *mstb,
2572 	const uint8_t *guid)
2573 {
2574 	struct drm_dp_mst_branch *found_mstb;
2575 	struct drm_dp_mst_port *port;
2576 
2577 	if (memcmp(mstb->guid, guid, 16) == 0)
2578 		return mstb;
2579 
2580 
2581 	list_for_each_entry(port, &mstb->ports, next) {
2582 		if (!port->mstb)
2583 			continue;
2584 
2585 		found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
2586 
2587 		if (found_mstb)
2588 			return found_mstb;
2589 	}
2590 
2591 	return NULL;
2592 }
2593 
2594 static struct drm_dp_mst_branch *
2595 drm_dp_get_mst_branch_device_by_guid(struct drm_dp_mst_topology_mgr *mgr,
2596 				     const uint8_t *guid)
2597 {
2598 	struct drm_dp_mst_branch *mstb;
2599 	int ret;
2600 
2601 	/* find the port by iterating down */
2602 	mutex_lock(&mgr->lock);
2603 
2604 	mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
2605 	if (mstb) {
2606 		ret = drm_dp_mst_topology_try_get_mstb(mstb);
2607 		if (!ret)
2608 			mstb = NULL;
2609 	}
2610 
2611 	mutex_unlock(&mgr->lock);
2612 	return mstb;
2613 }
2614 
2615 static int drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2616 					       struct drm_dp_mst_branch *mstb)
2617 {
2618 	struct drm_dp_mst_port *port;
2619 	int ret;
2620 	bool changed = false;
2621 
2622 	if (!mstb->link_address_sent) {
2623 		ret = drm_dp_send_link_address(mgr, mstb);
2624 		if (ret == 1)
2625 			changed = true;
2626 		else if (ret < 0)
2627 			return ret;
2628 	}
2629 
2630 	list_for_each_entry(port, &mstb->ports, next) {
2631 		if (port->input || !port->ddps || !port->mstb)
2632 			continue;
2633 
2634 		ret = drm_dp_check_and_send_link_address(mgr, port->mstb);
2635 		if (ret == 1)
2636 			changed = true;
2637 		else if (ret < 0)
2638 			return ret;
2639 	}
2640 
2641 	return changed;
2642 }
2643 
2644 static void drm_dp_mst_link_probe_work(struct work_struct *work)
2645 {
2646 	struct drm_dp_mst_topology_mgr *mgr =
2647 		container_of(work, struct drm_dp_mst_topology_mgr, work);
2648 	struct drm_device *dev = mgr->dev;
2649 	struct drm_dp_mst_branch *mstb;
2650 	int ret;
2651 	bool clear_payload_id_table;
2652 
2653 	mutex_lock(&mgr->probe_lock);
2654 
2655 	mutex_lock(&mgr->lock);
2656 	clear_payload_id_table = !mgr->payload_id_table_cleared;
2657 	mgr->payload_id_table_cleared = true;
2658 
2659 	mstb = mgr->mst_primary;
2660 	if (mstb) {
2661 		ret = drm_dp_mst_topology_try_get_mstb(mstb);
2662 		if (!ret)
2663 			mstb = NULL;
2664 	}
2665 	mutex_unlock(&mgr->lock);
2666 	if (!mstb) {
2667 		mutex_unlock(&mgr->probe_lock);
2668 		return;
2669 	}
2670 
2671 	/*
2672 	 * Certain branch devices seem to incorrectly report an available_pbn
2673 	 * of 0 on downstream sinks, even after clearing the
2674 	 * DP_PAYLOAD_ALLOCATE_* registers in
2675 	 * drm_dp_mst_topology_mgr_set_mst(). Namely, the CableMatters USB-C
2676 	 * 2x DP hub. Sending a CLEAR_PAYLOAD_ID_TABLE message seems to make
2677 	 * things work again.
2678 	 */
2679 	if (clear_payload_id_table) {
2680 		drm_dbg_kms(dev, "Clearing payload ID table\n");
2681 		drm_dp_send_clear_payload_id_table(mgr, mstb);
2682 	}
2683 
2684 	ret = drm_dp_check_and_send_link_address(mgr, mstb);
2685 	drm_dp_mst_topology_put_mstb(mstb);
2686 
2687 	mutex_unlock(&mgr->probe_lock);
2688 	if (ret > 0)
2689 		drm_kms_helper_hotplug_event(dev);
2690 }
2691 
2692 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
2693 				 u8 *guid)
2694 {
2695 	u64 salt;
2696 
2697 	if (memchr_inv(guid, 0, 16))
2698 		return true;
2699 
2700 	salt = get_jiffies_64();
2701 
2702 	memcpy(&guid[0], &salt, sizeof(u64));
2703 	memcpy(&guid[8], &salt, sizeof(u64));
2704 
2705 	return false;
2706 }
2707 
2708 static void build_dpcd_read(struct drm_dp_sideband_msg_tx *msg,
2709 			    u8 port_num, u32 offset, u8 num_bytes)
2710 {
2711 	struct drm_dp_sideband_msg_req_body req;
2712 
2713 	req.req_type = DP_REMOTE_DPCD_READ;
2714 	req.u.dpcd_read.port_number = port_num;
2715 	req.u.dpcd_read.dpcd_address = offset;
2716 	req.u.dpcd_read.num_bytes = num_bytes;
2717 	drm_dp_encode_sideband_req(&req, msg);
2718 }
2719 
2720 static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
2721 				    bool up, u8 *msg, int len)
2722 {
2723 	int ret;
2724 	int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;
2725 	int tosend, total, offset;
2726 	int retries = 0;
2727 
2728 retry:
2729 	total = len;
2730 	offset = 0;
2731 	do {
2732 		tosend = min3(mgr->max_dpcd_transaction_bytes, 16, total);
2733 
2734 		ret = drm_dp_dpcd_write(mgr->aux, regbase + offset,
2735 					&msg[offset],
2736 					tosend);
2737 		if (ret != tosend) {
2738 			if (ret == -EIO && retries < 5) {
2739 				retries++;
2740 				goto retry;
2741 			}
2742 			drm_dbg_kms(mgr->dev, "failed to dpcd write %d %d\n", tosend, ret);
2743 
2744 			return -EIO;
2745 		}
2746 		offset += tosend;
2747 		total -= tosend;
2748 	} while (total > 0);
2749 	return 0;
2750 }
2751 
2752 static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
2753 				  struct drm_dp_sideband_msg_tx *txmsg)
2754 {
2755 	struct drm_dp_mst_branch *mstb = txmsg->dst;
2756 	u8 req_type;
2757 
2758 	req_type = txmsg->msg[0] & 0x7f;
2759 	if (req_type == DP_CONNECTION_STATUS_NOTIFY ||
2760 		req_type == DP_RESOURCE_STATUS_NOTIFY ||
2761 		req_type == DP_CLEAR_PAYLOAD_ID_TABLE)
2762 		hdr->broadcast = 1;
2763 	else
2764 		hdr->broadcast = 0;
2765 	hdr->path_msg = txmsg->path_msg;
2766 	if (hdr->broadcast) {
2767 		hdr->lct = 1;
2768 		hdr->lcr = 6;
2769 	} else {
2770 		hdr->lct = mstb->lct;
2771 		hdr->lcr = mstb->lct - 1;
2772 	}
2773 
2774 	memcpy(hdr->rad, mstb->rad, hdr->lct / 2);
2775 
2776 	return 0;
2777 }
2778 /*
2779  * process a single block of the next message in the sideband queue
2780  */
2781 static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
2782 				   struct drm_dp_sideband_msg_tx *txmsg,
2783 				   bool up)
2784 {
2785 	u8 chunk[48];
2786 	struct drm_dp_sideband_msg_hdr hdr;
2787 	int len, space, idx, tosend;
2788 	int ret;
2789 
2790 	if (txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
2791 		return 0;
2792 
2793 	memset(&hdr, 0, sizeof(struct drm_dp_sideband_msg_hdr));
2794 
2795 	if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED)
2796 		txmsg->state = DRM_DP_SIDEBAND_TX_START_SEND;
2797 
2798 	/* make hdr from dst mst */
2799 	ret = set_hdr_from_dst_qlock(&hdr, txmsg);
2800 	if (ret < 0)
2801 		return ret;
2802 
2803 	/* amount left to send in this message */
2804 	len = txmsg->cur_len - txmsg->cur_offset;
2805 
2806 	/* 48 - sideband msg size - 1 byte for data CRC, x header bytes */
2807 	space = 48 - 1 - drm_dp_calc_sb_hdr_size(&hdr);
2808 
2809 	tosend = min(len, space);
2810 	if (len == txmsg->cur_len)
2811 		hdr.somt = 1;
2812 	if (space >= len)
2813 		hdr.eomt = 1;
2814 
2815 
2816 	hdr.msg_len = tosend + 1;
2817 	drm_dp_encode_sideband_msg_hdr(&hdr, chunk, &idx);
2818 	memcpy(&chunk[idx], &txmsg->msg[txmsg->cur_offset], tosend);
2819 	/* add crc at end */
2820 	drm_dp_crc_sideband_chunk_req(&chunk[idx], tosend);
2821 	idx += tosend + 1;
2822 
2823 	ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
2824 	if (ret) {
2825 		if (drm_debug_enabled(DRM_UT_DP)) {
2826 			struct drm_printer p = drm_debug_printer(DBG_PREFIX);
2827 
2828 			drm_printf(&p, "sideband msg failed to send\n");
2829 			drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
2830 		}
2831 		return ret;
2832 	}
2833 
2834 	txmsg->cur_offset += tosend;
2835 	if (txmsg->cur_offset == txmsg->cur_len) {
2836 		txmsg->state = DRM_DP_SIDEBAND_TX_SENT;
2837 		return 1;
2838 	}
2839 	return 0;
2840 }
2841 
2842 static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
2843 {
2844 	struct drm_dp_sideband_msg_tx *txmsg;
2845 	int ret;
2846 
2847 	WARN_ON(!mutex_is_locked(&mgr->qlock));
2848 
2849 	/* construct a chunk from the first msg in the tx_msg queue */
2850 	if (list_empty(&mgr->tx_msg_downq))
2851 		return;
2852 
2853 	txmsg = list_first_entry(&mgr->tx_msg_downq,
2854 				 struct drm_dp_sideband_msg_tx, next);
2855 	ret = process_single_tx_qlock(mgr, txmsg, false);
2856 	if (ret < 0) {
2857 		drm_dbg_kms(mgr->dev, "failed to send msg in q %d\n", ret);
2858 		list_del(&txmsg->next);
2859 		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
2860 		wake_up_all(&mgr->tx_waitq);
2861 	}
2862 }
2863 
2864 static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
2865 				 struct drm_dp_sideband_msg_tx *txmsg)
2866 {
2867 	mutex_lock(&mgr->qlock);
2868 	list_add_tail(&txmsg->next, &mgr->tx_msg_downq);
2869 
2870 	if (drm_debug_enabled(DRM_UT_DP)) {
2871 		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
2872 
2873 		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
2874 	}
2875 
2876 	if (list_is_singular(&mgr->tx_msg_downq))
2877 		process_single_down_tx_qlock(mgr);
2878 	mutex_unlock(&mgr->qlock);
2879 }
2880 
2881 static void
2882 drm_dp_dump_link_address(const struct drm_dp_mst_topology_mgr *mgr,
2883 			 struct drm_dp_link_address_ack_reply *reply)
2884 {
2885 	struct drm_dp_link_addr_reply_port *port_reply;
2886 	int i;
2887 
2888 	for (i = 0; i < reply->nports; i++) {
2889 		port_reply = &reply->ports[i];
2890 		drm_dbg_kms(mgr->dev,
2891 			    "port %d: input %d, pdt: %d, pn: %d, dpcd_rev: %02x, mcs: %d, ddps: %d, ldps %d, sdp %d/%d\n",
2892 			    i,
2893 			    port_reply->input_port,
2894 			    port_reply->peer_device_type,
2895 			    port_reply->port_number,
2896 			    port_reply->dpcd_revision,
2897 			    port_reply->mcs,
2898 			    port_reply->ddps,
2899 			    port_reply->legacy_device_plug_status,
2900 			    port_reply->num_sdp_streams,
2901 			    port_reply->num_sdp_stream_sinks);
2902 	}
2903 }
2904 
2905 static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2906 				     struct drm_dp_mst_branch *mstb)
2907 {
2908 	struct drm_dp_sideband_msg_tx *txmsg;
2909 	struct drm_dp_link_address_ack_reply *reply;
2910 	struct drm_dp_mst_port *port, *tmp;
2911 	int i, ret, port_mask = 0;
2912 	bool changed = false;
2913 
2914 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2915 	if (!txmsg)
2916 		return -ENOMEM;
2917 
2918 	txmsg->dst = mstb;
2919 	build_link_address(txmsg);
2920 
2921 	mstb->link_address_sent = true;
2922 	drm_dp_queue_down_tx(mgr, txmsg);
2923 
2924 	/* FIXME: Actually do some real error handling here */
2925 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2926 	if (ret <= 0) {
2927 		drm_err(mgr->dev, "Sending link address failed with %d\n", ret);
2928 		goto out;
2929 	}
2930 	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
2931 		drm_err(mgr->dev, "link address NAK received\n");
2932 		ret = -EIO;
2933 		goto out;
2934 	}
2935 
2936 	reply = &txmsg->reply.u.link_addr;
2937 	drm_dbg_kms(mgr->dev, "link address reply: %d\n", reply->nports);
2938 	drm_dp_dump_link_address(mgr, reply);
2939 
2940 	ret = drm_dp_check_mstb_guid(mstb, reply->guid);
2941 	if (ret) {
2942 		char buf[64];
2943 
2944 		drm_dp_mst_rad_to_str(mstb->rad, mstb->lct, buf, sizeof(buf));
2945 		drm_err(mgr->dev, "GUID check on %s failed: %d\n", buf, ret);
2946 		goto out;
2947 	}
2948 
2949 	for (i = 0; i < reply->nports; i++) {
2950 		port_mask |= BIT(reply->ports[i].port_number);
2951 		ret = drm_dp_mst_handle_link_address_port(mstb, mgr->dev,
2952 							  &reply->ports[i]);
2953 		if (ret == 1)
2954 			changed = true;
2955 		else if (ret < 0)
2956 			goto out;
2957 	}
2958 
2959 	/* Prune any ports that are currently a part of mstb in our in-memory
2960 	 * topology, but were not seen in this link address. Usually this
2961 	 * means that they were removed while the topology was out of sync,
2962 	 * e.g. during suspend/resume
2963 	 */
2964 	mutex_lock(&mgr->lock);
2965 	list_for_each_entry_safe(port, tmp, &mstb->ports, next) {
2966 		if (port_mask & BIT(port->port_num))
2967 			continue;
2968 
2969 		drm_dbg_kms(mgr->dev, "port %d was not in link address, removing\n",
2970 			    port->port_num);
2971 		list_del(&port->next);
2972 		drm_dp_mst_topology_put_port(port);
2973 		changed = true;
2974 	}
2975 	mutex_unlock(&mgr->lock);
2976 
2977 out:
2978 	if (ret <= 0)
2979 		mstb->link_address_sent = false;
2980 	kfree(txmsg);
2981 	return ret < 0 ? ret : changed;
2982 }
2983 
2984 static void
2985 drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
2986 				   struct drm_dp_mst_branch *mstb)
2987 {
2988 	struct drm_dp_sideband_msg_tx *txmsg;
2989 	int ret;
2990 
2991 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2992 	if (!txmsg)
2993 		return;
2994 
2995 	txmsg->dst = mstb;
2996 	build_clear_payload_id_table(txmsg);
2997 
2998 	drm_dp_queue_down_tx(mgr, txmsg);
2999 
3000 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3001 	if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3002 		drm_dbg_kms(mgr->dev, "clear payload table id nak received\n");
3003 
3004 	kfree(txmsg);
3005 }
3006 
3007 static int
3008 drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
3009 				struct drm_dp_mst_branch *mstb,
3010 				struct drm_dp_mst_port *port)
3011 {
3012 	struct drm_dp_enum_path_resources_ack_reply *path_res;
3013 	struct drm_dp_sideband_msg_tx *txmsg;
3014 	int ret;
3015 
3016 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3017 	if (!txmsg)
3018 		return -ENOMEM;
3019 
3020 	txmsg->dst = mstb;
3021 	build_enum_path_resources(txmsg, port->port_num);
3022 
3023 	drm_dp_queue_down_tx(mgr, txmsg);
3024 
3025 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3026 	if (ret > 0) {
3027 		ret = 0;
3028 		path_res = &txmsg->reply.u.path_resources;
3029 
3030 		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
3031 			drm_dbg_kms(mgr->dev, "enum path resources nak received\n");
3032 		} else {
3033 			if (port->port_num != path_res->port_number)
3034 				DRM_ERROR("got incorrect port in response\n");
3035 
3036 			drm_dbg_kms(mgr->dev, "enum path resources %d: %d %d\n",
3037 				    path_res->port_number,
3038 				    path_res->full_payload_bw_number,
3039 				    path_res->avail_payload_bw_number);
3040 
3041 			/*
3042 			 * If something changed, make sure we send a
3043 			 * hotplug
3044 			 */
3045 			if (port->full_pbn != path_res->full_payload_bw_number ||
3046 			    port->fec_capable != path_res->fec_capable)
3047 				ret = 1;
3048 
3049 			port->full_pbn = path_res->full_payload_bw_number;
3050 			port->fec_capable = path_res->fec_capable;
3051 		}
3052 	}
3053 
3054 	kfree(txmsg);
3055 	return ret;
3056 }
3057 
3058 static struct drm_dp_mst_port *drm_dp_get_last_connected_port_to_mstb(struct drm_dp_mst_branch *mstb)
3059 {
3060 	if (!mstb->port_parent)
3061 		return NULL;
3062 
3063 	if (mstb->port_parent->mstb != mstb)
3064 		return mstb->port_parent;
3065 
3066 	return drm_dp_get_last_connected_port_to_mstb(mstb->port_parent->parent);
3067 }
3068 
3069 /*
3070  * Searches upwards in the topology starting from mstb to try to find the
3071  * closest available parent of mstb that's still connected to the rest of the
3072  * topology. This can be used in order to perform operations like releasing
3073  * payloads, where the branch device which owned the payload may no longer be
3074  * around and thus would require that the payload on the last living relative
3075  * be freed instead.
3076  */
3077 static struct drm_dp_mst_branch *
3078 drm_dp_get_last_connected_port_and_mstb(struct drm_dp_mst_topology_mgr *mgr,
3079 					struct drm_dp_mst_branch *mstb,
3080 					int *port_num)
3081 {
3082 	struct drm_dp_mst_branch *rmstb = NULL;
3083 	struct drm_dp_mst_port *found_port;
3084 
3085 	mutex_lock(&mgr->lock);
3086 	if (!mgr->mst_primary)
3087 		goto out;
3088 
3089 	do {
3090 		found_port = drm_dp_get_last_connected_port_to_mstb(mstb);
3091 		if (!found_port)
3092 			break;
3093 
3094 		if (drm_dp_mst_topology_try_get_mstb(found_port->parent)) {
3095 			rmstb = found_port->parent;
3096 			*port_num = found_port->port_num;
3097 		} else {
3098 			/* Search again, starting from this parent */
3099 			mstb = found_port->parent;
3100 		}
3101 	} while (!rmstb);
3102 out:
3103 	mutex_unlock(&mgr->lock);
3104 	return rmstb;
3105 }
3106 
3107 static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr,
3108 				   struct drm_dp_mst_port *port,
3109 				   int id,
3110 				   int pbn)
3111 {
3112 	struct drm_dp_sideband_msg_tx *txmsg;
3113 	struct drm_dp_mst_branch *mstb;
3114 	int ret, port_num;
3115 	u8 sinks[DRM_DP_MAX_SDP_STREAMS];
3116 	int i;
3117 
3118 	port_num = port->port_num;
3119 	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3120 	if (!mstb) {
3121 		mstb = drm_dp_get_last_connected_port_and_mstb(mgr,
3122 							       port->parent,
3123 							       &port_num);
3124 
3125 		if (!mstb)
3126 			return -EINVAL;
3127 	}
3128 
3129 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3130 	if (!txmsg) {
3131 		ret = -ENOMEM;
3132 		goto fail_put;
3133 	}
3134 
3135 	for (i = 0; i < port->num_sdp_streams; i++)
3136 		sinks[i] = i;
3137 
3138 	txmsg->dst = mstb;
3139 	build_allocate_payload(txmsg, port_num,
3140 			       id,
3141 			       pbn, port->num_sdp_streams, sinks);
3142 
3143 	drm_dp_queue_down_tx(mgr, txmsg);
3144 
3145 	/*
3146 	 * FIXME: there is a small chance that between getting the last
3147 	 * connected mstb and sending the payload message, the last connected
3148 	 * mstb could also be removed from the topology. In the future, this
3149 	 * needs to be fixed by restarting the
3150 	 * drm_dp_get_last_connected_port_and_mstb() search in the event of a
3151 	 * timeout if the topology is still connected to the system.
3152 	 */
3153 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3154 	if (ret > 0) {
3155 		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3156 			ret = -EINVAL;
3157 		else
3158 			ret = 0;
3159 	}
3160 	kfree(txmsg);
3161 fail_put:
3162 	drm_dp_mst_topology_put_mstb(mstb);
3163 	return ret;
3164 }
3165 
3166 int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
3167 				 struct drm_dp_mst_port *port, bool power_up)
3168 {
3169 	struct drm_dp_sideband_msg_tx *txmsg;
3170 	int ret;
3171 
3172 	port = drm_dp_mst_topology_get_port_validated(mgr, port);
3173 	if (!port)
3174 		return -EINVAL;
3175 
3176 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3177 	if (!txmsg) {
3178 		drm_dp_mst_topology_put_port(port);
3179 		return -ENOMEM;
3180 	}
3181 
3182 	txmsg->dst = port->parent;
3183 	build_power_updown_phy(txmsg, port->port_num, power_up);
3184 	drm_dp_queue_down_tx(mgr, txmsg);
3185 
3186 	ret = drm_dp_mst_wait_tx_reply(port->parent, txmsg);
3187 	if (ret > 0) {
3188 		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3189 			ret = -EINVAL;
3190 		else
3191 			ret = 0;
3192 	}
3193 	kfree(txmsg);
3194 	drm_dp_mst_topology_put_port(port);
3195 
3196 	return ret;
3197 }
3198 EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
3199 
3200 int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
3201 		struct drm_dp_mst_port *port,
3202 		struct drm_dp_query_stream_enc_status_ack_reply *status)
3203 {
3204 	struct drm_dp_mst_topology_state *state;
3205 	struct drm_dp_mst_atomic_payload *payload;
3206 	struct drm_dp_sideband_msg_tx *txmsg;
3207 	u8 nonce[7];
3208 	int ret;
3209 
3210 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3211 	if (!txmsg)
3212 		return -ENOMEM;
3213 
3214 	port = drm_dp_mst_topology_get_port_validated(mgr, port);
3215 	if (!port) {
3216 		ret = -EINVAL;
3217 		goto out_get_port;
3218 	}
3219 
3220 	get_random_bytes(nonce, sizeof(nonce));
3221 
3222 	drm_modeset_lock(&mgr->base.lock, NULL);
3223 	state = to_drm_dp_mst_topology_state(mgr->base.state);
3224 	payload = drm_atomic_get_mst_payload_state(state, port);
3225 
3226 	/*
3227 	 * "Source device targets the QUERY_STREAM_ENCRYPTION_STATUS message
3228 	 *  transaction at the MST Branch device directly connected to the
3229 	 *  Source"
3230 	 */
3231 	txmsg->dst = mgr->mst_primary;
3232 
3233 	build_query_stream_enc_status(txmsg, payload->vcpi, nonce);
3234 
3235 	drm_dp_queue_down_tx(mgr, txmsg);
3236 
3237 	ret = drm_dp_mst_wait_tx_reply(mgr->mst_primary, txmsg);
3238 	if (ret < 0) {
3239 		goto out;
3240 	} else if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
3241 		drm_dbg_kms(mgr->dev, "query encryption status nak received\n");
3242 		ret = -ENXIO;
3243 		goto out;
3244 	}
3245 
3246 	ret = 0;
3247 	memcpy(status, &txmsg->reply.u.enc_status, sizeof(*status));
3248 
3249 out:
3250 	drm_modeset_unlock(&mgr->base.lock);
3251 	drm_dp_mst_topology_put_port(port);
3252 out_get_port:
3253 	kfree(txmsg);
3254 	return ret;
3255 }
3256 EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
3257 
3258 static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
3259 				       struct drm_dp_mst_atomic_payload *payload)
3260 {
3261 	return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot,
3262 					 payload->time_slots);
3263 }
3264 
3265 static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
3266 				       struct drm_dp_mst_atomic_payload *payload)
3267 {
3268 	int ret;
3269 	struct drm_dp_mst_port *port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
3270 
3271 	if (!port)
3272 		return -EIO;
3273 
3274 	ret = drm_dp_payload_send_msg(mgr, port, payload->vcpi, payload->pbn);
3275 	drm_dp_mst_topology_put_port(port);
3276 	return ret;
3277 }
3278 
3279 static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
3280 					struct drm_dp_mst_topology_state *mst_state,
3281 					struct drm_dp_mst_atomic_payload *payload)
3282 {
3283 	drm_dbg_kms(mgr->dev, "\n");
3284 
3285 	/* it's okay for these to fail */
3286 	drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
3287 	drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
3288 
3289 	return 0;
3290 }
3291 
3292 /**
3293  * drm_dp_add_payload_part1() - Execute payload update part 1
3294  * @mgr: Manager to use.
3295  * @mst_state: The MST atomic state
3296  * @payload: The payload to write
3297  *
3298  * Determines the starting time slot for the given payload, and programs the VCPI for this payload
3299  * into hardware. After calling this, the driver should generate ACT and payload packets.
3300  *
3301  * Returns: 0 on success, error code on failure. In the event that this fails,
3302  * @payload.vc_start_slot will also be set to -1.
3303  */
3304 int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
3305 			     struct drm_dp_mst_topology_state *mst_state,
3306 			     struct drm_dp_mst_atomic_payload *payload)
3307 {
3308 	struct drm_dp_mst_port *port;
3309 	int ret;
3310 
3311 	port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
3312 	if (!port)
3313 		return 0;
3314 
3315 	if (mgr->payload_count == 0)
3316 		mgr->next_start_slot = mst_state->start_slot;
3317 
3318 	payload->vc_start_slot = mgr->next_start_slot;
3319 
3320 	ret = drm_dp_create_payload_step1(mgr, payload);
3321 	drm_dp_mst_topology_put_port(port);
3322 	if (ret < 0) {
3323 		drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
3324 			 payload->port, ret);
3325 		payload->vc_start_slot = -1;
3326 		return ret;
3327 	}
3328 
3329 	mgr->payload_count++;
3330 	mgr->next_start_slot += payload->time_slots;
3331 
3332 	return 0;
3333 }
3334 EXPORT_SYMBOL(drm_dp_add_payload_part1);
3335 
3336 /**
3337  * drm_dp_remove_payload() - Remove an MST payload
3338  * @mgr: Manager to use.
3339  * @mst_state: The MST atomic state
3340  * @payload: The payload to write
3341  *
3342  * Removes a payload from an MST topology if it was successfully assigned a start slot. Also updates
3343  * the starting time slots of all other payloads which would have been shifted towards the start of
3344  * the VC table as a result. After calling this, the driver should generate ACT and payload packets.
3345  */
3346 void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
3347 			   struct drm_dp_mst_topology_state *mst_state,
3348 			   struct drm_dp_mst_atomic_payload *payload)
3349 {
3350 	struct drm_dp_mst_atomic_payload *pos;
3351 	bool send_remove = false;
3352 
3353 	/* We failed to make the payload, so nothing to do */
3354 	if (payload->vc_start_slot == -1)
3355 		return;
3356 
3357 	mutex_lock(&mgr->lock);
3358 	send_remove = drm_dp_mst_port_downstream_of_branch(payload->port, mgr->mst_primary);
3359 	mutex_unlock(&mgr->lock);
3360 
3361 	if (send_remove)
3362 		drm_dp_destroy_payload_step1(mgr, mst_state, payload);
3363 	else
3364 		drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in topology, not sending remove\n",
3365 			    payload->vcpi);
3366 
3367 	list_for_each_entry(pos, &mst_state->payloads, next) {
3368 		if (pos != payload && pos->vc_start_slot > payload->vc_start_slot)
3369 			pos->vc_start_slot -= payload->time_slots;
3370 	}
3371 	payload->vc_start_slot = -1;
3372 
3373 	mgr->payload_count--;
3374 	mgr->next_start_slot -= payload->time_slots;
3375 }
3376 EXPORT_SYMBOL(drm_dp_remove_payload);
3377 
3378 /**
3379  * drm_dp_add_payload_part2() - Execute payload update part 2
3380  * @mgr: Manager to use.
3381  * @state: The global atomic state
3382  * @payload: The payload to update
3383  *
3384  * If @payload was successfully assigned a starting time slot by drm_dp_add_payload_part1(), this
3385  * function will send the sideband messages to finish allocating this payload.
3386  *
3387  * Returns: 0 on success, negative error code on failure.
3388  */
3389 int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
3390 			     struct drm_atomic_state *state,
3391 			     struct drm_dp_mst_atomic_payload *payload)
3392 {
3393 	int ret = 0;
3394 
3395 	/* Skip failed payloads */
3396 	if (payload->vc_start_slot == -1) {
3397 		drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
3398 			    payload->port->connector->name);
3399 		return -EIO;
3400 	}
3401 
3402 	ret = drm_dp_create_payload_step2(mgr, payload);
3403 	if (ret < 0) {
3404 		if (!payload->delete)
3405 			drm_err(mgr->dev, "Step 2 of creating MST payload for %p failed: %d\n",
3406 				payload->port, ret);
3407 		else
3408 			drm_dbg_kms(mgr->dev, "Step 2 of removing MST payload for %p failed: %d\n",
3409 				    payload->port, ret);
3410 	}
3411 
3412 	return ret;
3413 }
3414 EXPORT_SYMBOL(drm_dp_add_payload_part2);
3415 
3416 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
3417 				 struct drm_dp_mst_port *port,
3418 				 int offset, int size, u8 *bytes)
3419 {
3420 	int ret = 0;
3421 	struct drm_dp_sideband_msg_tx *txmsg;
3422 	struct drm_dp_mst_branch *mstb;
3423 
3424 	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3425 	if (!mstb)
3426 		return -EINVAL;
3427 
3428 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3429 	if (!txmsg) {
3430 		ret = -ENOMEM;
3431 		goto fail_put;
3432 	}
3433 
3434 	build_dpcd_read(txmsg, port->port_num, offset, size);
3435 	txmsg->dst = port->parent;
3436 
3437 	drm_dp_queue_down_tx(mgr, txmsg);
3438 
3439 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3440 	if (ret < 0)
3441 		goto fail_free;
3442 
3443 	if (txmsg->reply.reply_type == 1) {
3444 		drm_dbg_kms(mgr->dev, "mstb %p port %d: DPCD read on addr 0x%x for %d bytes NAKed\n",
3445 			    mstb, port->port_num, offset, size);
3446 		ret = -EIO;
3447 		goto fail_free;
3448 	}
3449 
3450 	if (txmsg->reply.u.remote_dpcd_read_ack.num_bytes != size) {
3451 		ret = -EPROTO;
3452 		goto fail_free;
3453 	}
3454 
3455 	ret = min_t(size_t, txmsg->reply.u.remote_dpcd_read_ack.num_bytes,
3456 		    size);
3457 	memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, ret);
3458 
3459 fail_free:
3460 	kfree(txmsg);
3461 fail_put:
3462 	drm_dp_mst_topology_put_mstb(mstb);
3463 
3464 	return ret;
3465 }
3466 
3467 static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
3468 				  struct drm_dp_mst_port *port,
3469 				  int offset, int size, u8 *bytes)
3470 {
3471 	int ret;
3472 	struct drm_dp_sideband_msg_tx *txmsg;
3473 	struct drm_dp_mst_branch *mstb;
3474 
3475 	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3476 	if (!mstb)
3477 		return -EINVAL;
3478 
3479 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3480 	if (!txmsg) {
3481 		ret = -ENOMEM;
3482 		goto fail_put;
3483 	}
3484 
3485 	build_dpcd_write(txmsg, port->port_num, offset, size, bytes);
3486 	txmsg->dst = mstb;
3487 
3488 	drm_dp_queue_down_tx(mgr, txmsg);
3489 
3490 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3491 	if (ret > 0) {
3492 		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3493 			ret = -EIO;
3494 		else
3495 			ret = size;
3496 	}
3497 
3498 	kfree(txmsg);
3499 fail_put:
3500 	drm_dp_mst_topology_put_mstb(mstb);
3501 	return ret;
3502 }
3503 
3504 static int drm_dp_encode_up_ack_reply(struct drm_dp_sideband_msg_tx *msg, u8 req_type)
3505 {
3506 	struct drm_dp_sideband_msg_reply_body reply;
3507 
3508 	reply.reply_type = DP_SIDEBAND_REPLY_ACK;
3509 	reply.req_type = req_type;
3510 	drm_dp_encode_sideband_reply(&reply, msg);
3511 	return 0;
3512 }
3513 
3514 static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
3515 				    struct drm_dp_mst_branch *mstb,
3516 				    int req_type, bool broadcast)
3517 {
3518 	struct drm_dp_sideband_msg_tx *txmsg;
3519 
3520 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3521 	if (!txmsg)
3522 		return -ENOMEM;
3523 
3524 	txmsg->dst = mstb;
3525 	drm_dp_encode_up_ack_reply(txmsg, req_type);
3526 
3527 	mutex_lock(&mgr->qlock);
3528 	/* construct a chunk from the first msg in the tx_msg queue */
3529 	process_single_tx_qlock(mgr, txmsg, true);
3530 	mutex_unlock(&mgr->qlock);
3531 
3532 	kfree(txmsg);
3533 	return 0;
3534 }
3535 
3536 /**
3537  * drm_dp_get_vc_payload_bw - get the VC payload BW for an MST link
3538  * @mgr: The &drm_dp_mst_topology_mgr to use
3539  * @link_rate: link rate in 10kbits/s units
3540  * @link_lane_count: lane count
3541  *
3542  * Calculate the total bandwidth of a MultiStream Transport link. The returned
3543  * value is in units of PBNs/(timeslots/1 MTP). This value can be used to
3544  * convert the number of PBNs required for a given stream to the number of
3545  * timeslots this stream requires in each MTP.
3546  */
3547 int drm_dp_get_vc_payload_bw(const struct drm_dp_mst_topology_mgr *mgr,
3548 			     int link_rate, int link_lane_count)
3549 {
3550 	if (link_rate == 0 || link_lane_count == 0)
3551 		drm_dbg_kms(mgr->dev, "invalid link rate/lane count: (%d / %d)\n",
3552 			    link_rate, link_lane_count);
3553 
3554 	/* See DP v2.0 2.6.4.2, VCPayload_Bandwidth_for_OneTimeSlotPer_MTP_Allocation */
3555 	return link_rate * link_lane_count / 54000;
3556 }
3557 EXPORT_SYMBOL(drm_dp_get_vc_payload_bw);
3558 
3559 /**
3560  * drm_dp_read_mst_cap() - check whether or not a sink supports MST
3561  * @aux: The DP AUX channel to use
3562  * @dpcd: A cached copy of the DPCD capabilities for this sink
3563  *
3564  * Returns: %True if the sink supports MST, %false otherwise
3565  */
3566 bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
3567 			 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
3568 {
3569 	u8 mstm_cap;
3570 
3571 	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
3572 		return false;
3573 
3574 	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
3575 		return false;
3576 
3577 	return mstm_cap & DP_MST_CAP;
3578 }
3579 EXPORT_SYMBOL(drm_dp_read_mst_cap);
3580 
3581 /**
3582  * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
3583  * @mgr: manager to set state for
3584  * @mst_state: true to enable MST on this connector - false to disable.
3585  *
3586  * This is called by the driver when it detects an MST capable device plugged
3587  * into a DP MST capable port, or when a DP MST capable device is unplugged.
3588  */
3589 int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
3590 {
3591 	int ret = 0;
3592 	struct drm_dp_mst_branch *mstb = NULL;
3593 
3594 	mutex_lock(&mgr->lock);
3595 	if (mst_state == mgr->mst_state)
3596 		goto out_unlock;
3597 
3598 	mgr->mst_state = mst_state;
3599 	/* set the device into MST mode */
3600 	if (mst_state) {
3601 		WARN_ON(mgr->mst_primary);
3602 
3603 		/* get dpcd info */
3604 		ret = drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd);
3605 		if (ret < 0) {
3606 			drm_dbg_kms(mgr->dev, "%s: failed to read DPCD, ret %d\n",
3607 				    mgr->aux->name, ret);
3608 			goto out_unlock;
3609 		}
3610 
3611 		/* add initial branch device at LCT 1 */
3612 		mstb = drm_dp_add_mst_branch_device(1, NULL);
3613 		if (mstb == NULL) {
3614 			ret = -ENOMEM;
3615 			goto out_unlock;
3616 		}
3617 		mstb->mgr = mgr;
3618 
3619 		/* give this the main reference */
3620 		mgr->mst_primary = mstb;
3621 		drm_dp_mst_topology_get_mstb(mgr->mst_primary);
3622 
3623 		ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3624 					 DP_MST_EN |
3625 					 DP_UP_REQ_EN |
3626 					 DP_UPSTREAM_IS_SRC);
3627 		if (ret < 0)
3628 			goto out_unlock;
3629 
3630 		/* Write reset payload */
3631 		drm_dp_dpcd_write_payload(mgr, 0, 0, 0x3f);
3632 
3633 		queue_work(system_long_wq, &mgr->work);
3634 
3635 		ret = 0;
3636 	} else {
3637 		/* disable MST on the device */
3638 		mstb = mgr->mst_primary;
3639 		mgr->mst_primary = NULL;
3640 		/* this can fail if the device is gone */
3641 		drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
3642 		ret = 0;
3643 		mgr->payload_id_table_cleared = false;
3644 	}
3645 
3646 out_unlock:
3647 	mutex_unlock(&mgr->lock);
3648 	if (mstb)
3649 		drm_dp_mst_topology_put_mstb(mstb);
3650 	return ret;
3651 
3652 }
3653 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_set_mst);
3654 
3655 static void
3656 drm_dp_mst_topology_mgr_invalidate_mstb(struct drm_dp_mst_branch *mstb)
3657 {
3658 	struct drm_dp_mst_port *port;
3659 
3660 	/* The link address will need to be re-sent on resume */
3661 	mstb->link_address_sent = false;
3662 
3663 	list_for_each_entry(port, &mstb->ports, next)
3664 		if (port->mstb)
3665 			drm_dp_mst_topology_mgr_invalidate_mstb(port->mstb);
3666 }
3667 
3668 /**
3669  * drm_dp_mst_topology_mgr_suspend() - suspend the MST manager
3670  * @mgr: manager to suspend
3671  *
3672  * This function tells the MST device that we can't handle UP messages
3673  * anymore. This should stop it from sending any since we are suspended.
3674  */
3675 void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr)
3676 {
3677 	mutex_lock(&mgr->lock);
3678 	drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3679 			   DP_MST_EN | DP_UPSTREAM_IS_SRC);
3680 	mutex_unlock(&mgr->lock);
3681 	flush_work(&mgr->up_req_work);
3682 	flush_work(&mgr->work);
3683 	flush_work(&mgr->delayed_destroy_work);
3684 
3685 	mutex_lock(&mgr->lock);
3686 	if (mgr->mst_state && mgr->mst_primary)
3687 		drm_dp_mst_topology_mgr_invalidate_mstb(mgr->mst_primary);
3688 	mutex_unlock(&mgr->lock);
3689 }
3690 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_suspend);
3691 
3692 /**
3693  * drm_dp_mst_topology_mgr_resume() - resume the MST manager
3694  * @mgr: manager to resume
3695  * @sync: whether or not to perform topology reprobing synchronously
3696  *
3697  * This will fetch DPCD and see if the device is still there,
3698  * if it is, it will rewrite the MSTM control bits, and return.
3699  *
3700  * If the device fails this returns -1, and the driver should do
3701  * a full MST reprobe, in case we were undocked.
3702  *
3703  * During system resume (where it is assumed that the driver will be calling
3704  * drm_atomic_helper_resume()) this function should be called beforehand with
3705  * @sync set to true. In contexts like runtime resume where the driver is not
3706  * expected to be calling drm_atomic_helper_resume(), this function should be
3707  * called with @sync set to false in order to avoid deadlocking.
3708  *
3709  * Returns: -1 if the MST topology was removed while we were suspended, 0
3710  * otherwise.
3711  */
3712 int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
3713 				   bool sync)
3714 {
3715 	int ret;
3716 	u8 guid[16];
3717 
3718 	mutex_lock(&mgr->lock);
3719 	if (!mgr->mst_primary)
3720 		goto out_fail;
3721 
3722 	if (drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd) < 0) {
3723 		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
3724 		goto out_fail;
3725 	}
3726 
3727 	ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3728 				 DP_MST_EN |
3729 				 DP_UP_REQ_EN |
3730 				 DP_UPSTREAM_IS_SRC);
3731 	if (ret < 0) {
3732 		drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n");
3733 		goto out_fail;
3734 	}
3735 
3736 	/* Some hubs forget their guids after they resume */
3737 	ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
3738 	if (ret != 16) {
3739 		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
3740 		goto out_fail;
3741 	}
3742 
3743 	ret = drm_dp_check_mstb_guid(mgr->mst_primary, guid);
3744 	if (ret) {
3745 		drm_dbg_kms(mgr->dev, "check mstb failed - undocked during suspend?\n");
3746 		goto out_fail;
3747 	}
3748 
3749 	/*
3750 	 * For the final step of resuming the topology, we need to bring the
3751 	 * state of our in-memory topology back into sync with reality. So,
3752 	 * restart the probing process as if we're probing a new hub
3753 	 */
3754 	queue_work(system_long_wq, &mgr->work);
3755 	mutex_unlock(&mgr->lock);
3756 
3757 	if (sync) {
3758 		drm_dbg_kms(mgr->dev,
3759 			    "Waiting for link probe work to finish re-syncing topology...\n");
3760 		flush_work(&mgr->work);
3761 	}
3762 
3763 	return 0;
3764 
3765 out_fail:
3766 	mutex_unlock(&mgr->lock);
3767 	return -1;
3768 }
3769 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
3770 
3771 static bool
3772 drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up,
3773 		      struct drm_dp_mst_branch **mstb)
3774 {
3775 	int len;
3776 	u8 replyblock[32];
3777 	int replylen, curreply;
3778 	int ret;
3779 	u8 hdrlen;
3780 	struct drm_dp_sideband_msg_hdr hdr;
3781 	struct drm_dp_sideband_msg_rx *msg =
3782 		up ? &mgr->up_req_recv : &mgr->down_rep_recv;
3783 	int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE :
3784 			   DP_SIDEBAND_MSG_DOWN_REP_BASE;
3785 
3786 	if (!up)
3787 		*mstb = NULL;
3788 
3789 	len = min(mgr->max_dpcd_transaction_bytes, 16);
3790 	ret = drm_dp_dpcd_read(mgr->aux, basereg, replyblock, len);
3791 	if (ret != len) {
3792 		drm_dbg_kms(mgr->dev, "failed to read DPCD down rep %d %d\n", len, ret);
3793 		return false;
3794 	}
3795 
3796 	ret = drm_dp_decode_sideband_msg_hdr(mgr, &hdr, replyblock, len, &hdrlen);
3797 	if (ret == false) {
3798 		print_hex_dump(KERN_DEBUG, "failed hdr", DUMP_PREFIX_NONE, 16,
3799 			       1, replyblock, len, false);
3800 		drm_dbg_kms(mgr->dev, "ERROR: failed header\n");
3801 		return false;
3802 	}
3803 
3804 	if (!up) {
3805 		/* Caller is responsible for giving back this reference */
3806 		*mstb = drm_dp_get_mst_branch_device(mgr, hdr.lct, hdr.rad);
3807 		if (!*mstb) {
3808 			drm_dbg_kms(mgr->dev, "Got MST reply from unknown device %d\n", hdr.lct);
3809 			return false;
3810 		}
3811 	}
3812 
3813 	if (!drm_dp_sideband_msg_set_header(msg, &hdr, hdrlen)) {
3814 		drm_dbg_kms(mgr->dev, "sideband msg set header failed %d\n", replyblock[0]);
3815 		return false;
3816 	}
3817 
3818 	replylen = min(msg->curchunk_len, (u8)(len - hdrlen));
3819 	ret = drm_dp_sideband_append_payload(msg, replyblock + hdrlen, replylen);
3820 	if (!ret) {
3821 		drm_dbg_kms(mgr->dev, "sideband msg build failed %d\n", replyblock[0]);
3822 		return false;
3823 	}
3824 
3825 	replylen = msg->curchunk_len + msg->curchunk_hdrlen - len;
3826 	curreply = len;
3827 	while (replylen > 0) {
3828 		len = min3(replylen, mgr->max_dpcd_transaction_bytes, 16);
3829 		ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
3830 				    replyblock, len);
3831 		if (ret != len) {
3832 			drm_dbg_kms(mgr->dev, "failed to read a chunk (len %d, ret %d)\n",
3833 				    len, ret);
3834 			return false;
3835 		}
3836 
3837 		ret = drm_dp_sideband_append_payload(msg, replyblock, len);
3838 		if (!ret) {
3839 			drm_dbg_kms(mgr->dev, "failed to build sideband msg\n");
3840 			return false;
3841 		}
3842 
3843 		curreply += len;
3844 		replylen -= len;
3845 	}
3846 	return true;
3847 }
3848 
3849 static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
3850 {
3851 	struct drm_dp_sideband_msg_tx *txmsg;
3852 	struct drm_dp_mst_branch *mstb = NULL;
3853 	struct drm_dp_sideband_msg_rx *msg = &mgr->down_rep_recv;
3854 
3855 	if (!drm_dp_get_one_sb_msg(mgr, false, &mstb))
3856 		goto out;
3857 
3858 	/* Multi-packet message transmission, don't clear the reply */
3859 	if (!msg->have_eomt)
3860 		goto out;
3861 
3862 	/* find the message */
3863 	mutex_lock(&mgr->qlock);
3864 	txmsg = list_first_entry_or_null(&mgr->tx_msg_downq,
3865 					 struct drm_dp_sideband_msg_tx, next);
3866 	mutex_unlock(&mgr->qlock);
3867 
3868 	/* Were we actually expecting a response, and from this mstb? */
3869 	if (!txmsg || txmsg->dst != mstb) {
3870 		struct drm_dp_sideband_msg_hdr *hdr;
3871 
3872 		hdr = &msg->initial_hdr;
3873 		drm_dbg_kms(mgr->dev, "Got MST reply with no msg %p %d %d %02x %02x\n",
3874 			    mstb, hdr->seqno, hdr->lct, hdr->rad[0], msg->msg[0]);
3875 		goto out_clear_reply;
3876 	}
3877 
3878 	drm_dp_sideband_parse_reply(mgr, msg, &txmsg->reply);
3879 
3880 	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
3881 		drm_dbg_kms(mgr->dev,
3882 			    "Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
3883 			    txmsg->reply.req_type,
3884 			    drm_dp_mst_req_type_str(txmsg->reply.req_type),
3885 			    txmsg->reply.u.nak.reason,
3886 			    drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
3887 			    txmsg->reply.u.nak.nak_data);
3888 	}
3889 
3890 	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
3891 	drm_dp_mst_topology_put_mstb(mstb);
3892 
3893 	mutex_lock(&mgr->qlock);
3894 	txmsg->state = DRM_DP_SIDEBAND_TX_RX;
3895 	list_del(&txmsg->next);
3896 	mutex_unlock(&mgr->qlock);
3897 
3898 	wake_up_all(&mgr->tx_waitq);
3899 
3900 	return 0;
3901 
3902 out_clear_reply:
3903 	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
3904 out:
3905 	if (mstb)
3906 		drm_dp_mst_topology_put_mstb(mstb);
3907 
3908 	return 0;
3909 }
3910 
3911 static inline bool
3912 drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
3913 			  struct drm_dp_pending_up_req *up_req)
3914 {
3915 	struct drm_dp_mst_branch *mstb = NULL;
3916 	struct drm_dp_sideband_msg_req_body *msg = &up_req->msg;
3917 	struct drm_dp_sideband_msg_hdr *hdr = &up_req->hdr;
3918 	bool hotplug = false, dowork = false;
3919 
3920 	if (hdr->broadcast) {
3921 		const u8 *guid = NULL;
3922 
3923 		if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY)
3924 			guid = msg->u.conn_stat.guid;
3925 		else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY)
3926 			guid = msg->u.resource_stat.guid;
3927 
3928 		if (guid)
3929 			mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid);
3930 	} else {
3931 		mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
3932 	}
3933 
3934 	if (!mstb) {
3935 		drm_dbg_kms(mgr->dev, "Got MST reply from unknown device %d\n", hdr->lct);
3936 		return false;
3937 	}
3938 
3939 	/* TODO: Add missing handler for DP_RESOURCE_STATUS_NOTIFY events */
3940 	if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY) {
3941 		dowork = drm_dp_mst_handle_conn_stat(mstb, &msg->u.conn_stat);
3942 		hotplug = true;
3943 	}
3944 
3945 	drm_dp_mst_topology_put_mstb(mstb);
3946 
3947 	if (dowork)
3948 		queue_work(system_long_wq, &mgr->work);
3949 	return hotplug;
3950 }
3951 
3952 static void drm_dp_mst_up_req_work(struct work_struct *work)
3953 {
3954 	struct drm_dp_mst_topology_mgr *mgr =
3955 		container_of(work, struct drm_dp_mst_topology_mgr,
3956 			     up_req_work);
3957 	struct drm_dp_pending_up_req *up_req;
3958 	bool send_hotplug = false;
3959 
3960 	mutex_lock(&mgr->probe_lock);
3961 	while (true) {
3962 		mutex_lock(&mgr->up_req_lock);
3963 		up_req = list_first_entry_or_null(&mgr->up_req_list,
3964 						  struct drm_dp_pending_up_req,
3965 						  next);
3966 		if (up_req)
3967 			list_del(&up_req->next);
3968 		mutex_unlock(&mgr->up_req_lock);
3969 
3970 		if (!up_req)
3971 			break;
3972 
3973 		send_hotplug |= drm_dp_mst_process_up_req(mgr, up_req);
3974 		kfree(up_req);
3975 	}
3976 	mutex_unlock(&mgr->probe_lock);
3977 
3978 	if (send_hotplug)
3979 		drm_kms_helper_hotplug_event(mgr->dev);
3980 }
3981 
3982 static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
3983 {
3984 	struct drm_dp_pending_up_req *up_req;
3985 
3986 	if (!drm_dp_get_one_sb_msg(mgr, true, NULL))
3987 		goto out;
3988 
3989 	if (!mgr->up_req_recv.have_eomt)
3990 		return 0;
3991 
3992 	up_req = kzalloc(sizeof(*up_req), GFP_KERNEL);
3993 	if (!up_req)
3994 		return -ENOMEM;
3995 
3996 	INIT_LIST_HEAD(&up_req->next);
3997 
3998 	drm_dp_sideband_parse_req(mgr, &mgr->up_req_recv, &up_req->msg);
3999 
4000 	if (up_req->msg.req_type != DP_CONNECTION_STATUS_NOTIFY &&
4001 	    up_req->msg.req_type != DP_RESOURCE_STATUS_NOTIFY) {
4002 		drm_dbg_kms(mgr->dev, "Received unknown up req type, ignoring: %x\n",
4003 			    up_req->msg.req_type);
4004 		kfree(up_req);
4005 		goto out;
4006 	}
4007 
4008 	drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, up_req->msg.req_type,
4009 				 false);
4010 
4011 	if (up_req->msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
4012 		const struct drm_dp_connection_status_notify *conn_stat =
4013 			&up_req->msg.u.conn_stat;
4014 
4015 		drm_dbg_kms(mgr->dev, "Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n",
4016 			    conn_stat->port_number,
4017 			    conn_stat->legacy_device_plug_status,
4018 			    conn_stat->displayport_device_plug_status,
4019 			    conn_stat->message_capability_status,
4020 			    conn_stat->input_port,
4021 			    conn_stat->peer_device_type);
4022 	} else if (up_req->msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
4023 		const struct drm_dp_resource_status_notify *res_stat =
4024 			&up_req->msg.u.resource_stat;
4025 
4026 		drm_dbg_kms(mgr->dev, "Got RSN: pn: %d avail_pbn %d\n",
4027 			    res_stat->port_number,
4028 			    res_stat->available_pbn);
4029 	}
4030 
4031 	up_req->hdr = mgr->up_req_recv.initial_hdr;
4032 	mutex_lock(&mgr->up_req_lock);
4033 	list_add_tail(&up_req->next, &mgr->up_req_list);
4034 	mutex_unlock(&mgr->up_req_lock);
4035 	queue_work(system_long_wq, &mgr->up_req_work);
4036 
4037 out:
4038 	memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
4039 	return 0;
4040 }
4041 
4042 /**
4043  * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
4044  * @mgr: manager to notify irq for.
4045  * @esi: 4 bytes from SINK_COUNT_ESI
4046  * @handled: whether the hpd interrupt was consumed or not
4047  *
4048  * This should be called from the driver when it detects a short IRQ,
4049  * along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The
4050  * topology manager will process the sideband messages received as a result
4051  * of this.
4052  */
4053 int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
4054 {
4055 	int ret = 0;
4056 	int sc;
4057 	*handled = false;
4058 	sc = DP_GET_SINK_COUNT(esi[0]);
4059 
4060 	if (sc != mgr->sink_count) {
4061 		mgr->sink_count = sc;
4062 		*handled = true;
4063 	}
4064 
4065 	if (esi[1] & DP_DOWN_REP_MSG_RDY) {
4066 		ret = drm_dp_mst_handle_down_rep(mgr);
4067 		*handled = true;
4068 	}
4069 
4070 	if (esi[1] & DP_UP_REQ_MSG_RDY) {
4071 		ret |= drm_dp_mst_handle_up_req(mgr);
4072 		*handled = true;
4073 	}
4074 
4075 	drm_dp_mst_kick_tx(mgr);
4076 	return ret;
4077 }
4078 EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
4079 
4080 /**
4081  * drm_dp_mst_detect_port() - get connection status for an MST port
4082  * @connector: DRM connector for this port
4083  * @ctx: The acquisition context to use for grabbing locks
4084  * @mgr: manager for this port
4085  * @port: pointer to a port
4086  *
4087  * This returns the current connection state for a port.
4088  */
4089 int
4090 drm_dp_mst_detect_port(struct drm_connector *connector,
4091 		       struct drm_modeset_acquire_ctx *ctx,
4092 		       struct drm_dp_mst_topology_mgr *mgr,
4093 		       struct drm_dp_mst_port *port)
4094 {
4095 	int ret;
4096 
4097 	/* we need to search for the port in the mgr in case it's gone */
4098 	port = drm_dp_mst_topology_get_port_validated(mgr, port);
4099 	if (!port)
4100 		return connector_status_disconnected;
4101 
4102 	ret = drm_modeset_lock(&mgr->base.lock, ctx);
4103 	if (ret)
4104 		goto out;
4105 
4106 	ret = connector_status_disconnected;
4107 
4108 	if (!port->ddps)
4109 		goto out;
4110 
4111 	switch (port->pdt) {
4112 	case DP_PEER_DEVICE_NONE:
4113 		break;
4114 	case DP_PEER_DEVICE_MST_BRANCHING:
4115 		if (!port->mcs)
4116 			ret = connector_status_connected;
4117 		break;
4118 
4119 	case DP_PEER_DEVICE_SST_SINK:
4120 		ret = connector_status_connected;
4121 		/* for logical ports - cache the EDID */
4122 		if (port->port_num >= DP_MST_LOGICAL_PORT_0 && !port->cached_edid)
4123 			port->cached_edid = drm_get_edid(connector, &port->aux.ddc);
4124 		break;
4125 	case DP_PEER_DEVICE_DP_LEGACY_CONV:
4126 		if (port->ldps)
4127 			ret = connector_status_connected;
4128 		break;
4129 	}
4130 out:
4131 	drm_dp_mst_topology_put_port(port);
4132 	return ret;
4133 }
4134 EXPORT_SYMBOL(drm_dp_mst_detect_port);
4135 
4136 /**
4137  * drm_dp_mst_get_edid() - get EDID for an MST port
4138  * @connector: toplevel connector to get EDID for
4139  * @mgr: manager for this port
4140  * @port: unverified pointer to a port.
4141  *
4142  * This returns an EDID for the port connected to a connector,
4143  * It validates the pointer still exists so the caller doesn't require a
4144  * reference.
4145  */
4146 struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4147 {
4148 	struct edid *edid = NULL;
4149 
4150 	/* we need to search for the port in the mgr in case it's gone */
4151 	port = drm_dp_mst_topology_get_port_validated(mgr, port);
4152 	if (!port)
4153 		return NULL;
4154 
4155 	if (port->cached_edid)
4156 		edid = drm_edid_duplicate(port->cached_edid);
4157 	else {
4158 		edid = drm_get_edid(connector, &port->aux.ddc);
4159 	}
4160 	port->has_audio = drm_detect_monitor_audio(edid);
4161 	drm_dp_mst_topology_put_port(port);
4162 	return edid;
4163 }
4164 EXPORT_SYMBOL(drm_dp_mst_get_edid);
4165 
4166 /**
4167  * drm_dp_atomic_find_time_slots() - Find and add time slots to the state
4168  * @state: global atomic state
4169  * @mgr: MST topology manager for the port
4170  * @port: port to find time slots for
4171  * @pbn: bandwidth required for the mode in PBN
4172  *
4173  * Allocates time slots to @port, replacing any previous time slot allocations it may
4174  * have had. Any atomic drivers which support MST must call this function in
4175  * their &drm_encoder_helper_funcs.atomic_check() callback unconditionally to
4176  * change the current time slot allocation for the new state, and ensure the MST
4177  * atomic state is added whenever the state of payloads in the topology changes.
4178  *
4179  * Allocations set by this function are not checked against the bandwidth
4180  * restraints of @mgr until the driver calls drm_dp_mst_atomic_check().
4181  *
4182  * Additionally, it is OK to call this function multiple times on the same
4183  * @port as needed. It is not OK however, to call this function and
4184  * drm_dp_atomic_release_time_slots() in the same atomic check phase.
4185  *
4186  * See also:
4187  * drm_dp_atomic_release_time_slots()
4188  * drm_dp_mst_atomic_check()
4189  *
4190  * Returns:
4191  * Total slots in the atomic state assigned for this port, or a negative error
4192  * code if the port no longer exists
4193  */
4194 int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state,
4195 				  struct drm_dp_mst_topology_mgr *mgr,
4196 				  struct drm_dp_mst_port *port, int pbn)
4197 {
4198 	struct drm_dp_mst_topology_state *topology_state;
4199 	struct drm_dp_mst_atomic_payload *payload = NULL;
4200 	struct drm_connector_state *conn_state;
4201 	int prev_slots = 0, prev_bw = 0, req_slots;
4202 
4203 	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
4204 	if (IS_ERR(topology_state))
4205 		return PTR_ERR(topology_state);
4206 
4207 	conn_state = drm_atomic_get_new_connector_state(state, port->connector);
4208 	topology_state->pending_crtc_mask |= drm_crtc_mask(conn_state->crtc);
4209 
4210 	/* Find the current allocation for this port, if any */
4211 	payload = drm_atomic_get_mst_payload_state(topology_state, port);
4212 	if (payload) {
4213 		prev_slots = payload->time_slots;
4214 		prev_bw = payload->pbn;
4215 
4216 		/*
4217 		 * This should never happen, unless the driver tries
4218 		 * releasing and allocating the same timeslot allocation,
4219 		 * which is an error
4220 		 */
4221 		if (drm_WARN_ON(mgr->dev, payload->delete)) {
4222 			drm_err(mgr->dev,
4223 				"cannot allocate and release time slots on [MST PORT:%p] in the same state\n",
4224 				port);
4225 			return -EINVAL;
4226 		}
4227 	}
4228 
4229 	req_slots = DIV_ROUND_UP(pbn, topology_state->pbn_div);
4230 
4231 	drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] TU %d -> %d\n",
4232 		       port->connector->base.id, port->connector->name,
4233 		       port, prev_slots, req_slots);
4234 	drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n",
4235 		       port->connector->base.id, port->connector->name,
4236 		       port, prev_bw, pbn);
4237 
4238 	/* Add the new allocation to the state, note the VCPI isn't assigned until the end */
4239 	if (!payload) {
4240 		payload = kzalloc(sizeof(*payload), GFP_KERNEL);
4241 		if (!payload)
4242 			return -ENOMEM;
4243 
4244 		drm_dp_mst_get_port_malloc(port);
4245 		payload->port = port;
4246 		payload->vc_start_slot = -1;
4247 		list_add(&payload->next, &topology_state->payloads);
4248 	}
4249 	payload->time_slots = req_slots;
4250 	payload->pbn = pbn;
4251 
4252 	return req_slots;
4253 }
4254 EXPORT_SYMBOL(drm_dp_atomic_find_time_slots);
4255 
4256 /**
4257  * drm_dp_atomic_release_time_slots() - Release allocated time slots
4258  * @state: global atomic state
4259  * @mgr: MST topology manager for the port
4260  * @port: The port to release the time slots from
4261  *
4262  * Releases any time slots that have been allocated to a port in the atomic
4263  * state. Any atomic drivers which support MST must call this function
4264  * unconditionally in their &drm_connector_helper_funcs.atomic_check() callback.
4265  * This helper will check whether time slots would be released by the new state and
4266  * respond accordingly, along with ensuring the MST state is always added to the
4267  * atomic state whenever a new state would modify the state of payloads on the
4268  * topology.
4269  *
4270  * It is OK to call this even if @port has been removed from the system.
4271  * Additionally, it is OK to call this function multiple times on the same
4272  * @port as needed. It is not OK however, to call this function and
4273  * drm_dp_atomic_find_time_slots() on the same @port in a single atomic check
4274  * phase.
4275  *
4276  * See also:
4277  * drm_dp_atomic_find_time_slots()
4278  * drm_dp_mst_atomic_check()
4279  *
4280  * Returns:
4281  * 0 on success, negative error code otherwise
4282  */
4283 int drm_dp_atomic_release_time_slots(struct drm_atomic_state *state,
4284 				     struct drm_dp_mst_topology_mgr *mgr,
4285 				     struct drm_dp_mst_port *port)
4286 {
4287 	struct drm_dp_mst_topology_state *topology_state;
4288 	struct drm_dp_mst_atomic_payload *payload;
4289 	struct drm_connector_state *old_conn_state, *new_conn_state;
4290 	bool update_payload = true;
4291 
4292 	old_conn_state = drm_atomic_get_old_connector_state(state, port->connector);
4293 	if (!old_conn_state->crtc)
4294 		return 0;
4295 
4296 	/* If the CRTC isn't disabled by this state, don't release it's payload */
4297 	new_conn_state = drm_atomic_get_new_connector_state(state, port->connector);
4298 	if (new_conn_state->crtc) {
4299 		struct drm_crtc_state *crtc_state =
4300 			drm_atomic_get_new_crtc_state(state, new_conn_state->crtc);
4301 
4302 		/* No modeset means no payload changes, so it's safe to not pull in the MST state */
4303 		if (!crtc_state || !drm_atomic_crtc_needs_modeset(crtc_state))
4304 			return 0;
4305 
4306 		if (!crtc_state->mode_changed && !crtc_state->connectors_changed)
4307 			update_payload = false;
4308 	}
4309 
4310 	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
4311 	if (IS_ERR(topology_state))
4312 		return PTR_ERR(topology_state);
4313 
4314 	topology_state->pending_crtc_mask |= drm_crtc_mask(old_conn_state->crtc);
4315 	if (!update_payload)
4316 		return 0;
4317 
4318 	payload = drm_atomic_get_mst_payload_state(topology_state, port);
4319 	if (WARN_ON(!payload)) {
4320 		drm_err(mgr->dev, "No payload for [MST PORT:%p] found in mst state %p\n",
4321 			port, &topology_state->base);
4322 		return -EINVAL;
4323 	}
4324 
4325 	if (new_conn_state->crtc)
4326 		return 0;
4327 
4328 	drm_dbg_atomic(mgr->dev, "[MST PORT:%p] TU %d -> 0\n", port, payload->time_slots);
4329 	if (!payload->delete) {
4330 		drm_dp_mst_put_port_malloc(port);
4331 		payload->pbn = 0;
4332 		payload->delete = true;
4333 		topology_state->payload_mask &= ~BIT(payload->vcpi - 1);
4334 	}
4335 
4336 	return 0;
4337 }
4338 EXPORT_SYMBOL(drm_dp_atomic_release_time_slots);
4339 
4340 /**
4341  * drm_dp_mst_atomic_setup_commit() - setup_commit hook for MST helpers
4342  * @state: global atomic state
4343  *
4344  * This function saves all of the &drm_crtc_commit structs in an atomic state that touch any CRTCs
4345  * currently assigned to an MST topology. Drivers must call this hook from their
4346  * &drm_mode_config_helper_funcs.atomic_commit_setup hook.
4347  *
4348  * Returns:
4349  * 0 if all CRTC commits were retrieved successfully, negative error code otherwise
4350  */
4351 int drm_dp_mst_atomic_setup_commit(struct drm_atomic_state *state)
4352 {
4353 	struct drm_dp_mst_topology_mgr *mgr;
4354 	struct drm_dp_mst_topology_state *mst_state;
4355 	struct drm_crtc *crtc;
4356 	struct drm_crtc_state *crtc_state;
4357 	int i, j, commit_idx, num_commit_deps;
4358 
4359 	for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
4360 		if (!mst_state->pending_crtc_mask)
4361 			continue;
4362 
4363 		num_commit_deps = hweight32(mst_state->pending_crtc_mask);
4364 		mst_state->commit_deps = kmalloc_array(num_commit_deps,
4365 						       sizeof(*mst_state->commit_deps), GFP_KERNEL);
4366 		if (!mst_state->commit_deps)
4367 			return -ENOMEM;
4368 		mst_state->num_commit_deps = num_commit_deps;
4369 
4370 		commit_idx = 0;
4371 		for_each_new_crtc_in_state(state, crtc, crtc_state, j) {
4372 			if (mst_state->pending_crtc_mask & drm_crtc_mask(crtc)) {
4373 				mst_state->commit_deps[commit_idx++] =
4374 					drm_crtc_commit_get(crtc_state->commit);
4375 			}
4376 		}
4377 	}
4378 
4379 	return 0;
4380 }
4381 EXPORT_SYMBOL(drm_dp_mst_atomic_setup_commit);
4382 
4383 /**
4384  * drm_dp_mst_atomic_wait_for_dependencies() - Wait for all pending commits on MST topologies,
4385  * prepare new MST state for commit
4386  * @state: global atomic state
4387  *
4388  * Goes through any MST topologies in this atomic state, and waits for any pending commits which
4389  * touched CRTCs that were/are on an MST topology to be programmed to hardware and flipped to before
4390  * returning. This is to prevent multiple non-blocking commits affecting an MST topology from racing
4391  * with eachother by forcing them to be executed sequentially in situations where the only resources
4392  * the modeset objects in these commits share are an MST topology.
4393  *
4394  * This function also prepares the new MST state for commit by performing some state preparation
4395  * which can't be done until this point, such as reading back the final VC start slots (which are
4396  * determined at commit-time) from the previous state.
4397  *
4398  * All MST drivers must call this function after calling drm_atomic_helper_wait_for_dependencies(),
4399  * or whatever their equivalent of that is.
4400  */
4401 void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
4402 {
4403 	struct drm_dp_mst_topology_state *old_mst_state, *new_mst_state;
4404 	struct drm_dp_mst_topology_mgr *mgr;
4405 	struct drm_dp_mst_atomic_payload *old_payload, *new_payload;
4406 	int i, j, ret;
4407 
4408 	for_each_oldnew_mst_mgr_in_state(state, mgr, old_mst_state, new_mst_state, i) {
4409 		for (j = 0; j < old_mst_state->num_commit_deps; j++) {
4410 			ret = drm_crtc_commit_wait(old_mst_state->commit_deps[j]);
4411 			if (ret < 0)
4412 				drm_err(state->dev, "Failed to wait for %s: %d\n",
4413 					old_mst_state->commit_deps[j]->crtc->name, ret);
4414 		}
4415 
4416 		/* Now that previous state is committed, it's safe to copy over the start slot
4417 		 * assignments
4418 		 */
4419 		list_for_each_entry(old_payload, &old_mst_state->payloads, next) {
4420 			if (old_payload->delete)
4421 				continue;
4422 
4423 			new_payload = drm_atomic_get_mst_payload_state(new_mst_state,
4424 								       old_payload->port);
4425 			new_payload->vc_start_slot = old_payload->vc_start_slot;
4426 		}
4427 	}
4428 }
4429 EXPORT_SYMBOL(drm_dp_mst_atomic_wait_for_dependencies);
4430 
4431 /**
4432  * drm_dp_mst_root_conn_atomic_check() - Serialize CRTC commits on MST-capable connectors operating
4433  * in SST mode
4434  * @new_conn_state: The new connector state of the &drm_connector
4435  * @mgr: The MST topology manager for the &drm_connector
4436  *
4437  * Since MST uses fake &drm_encoder structs, the generic atomic modesetting code isn't able to
4438  * serialize non-blocking commits happening on the real DP connector of an MST topology switching
4439  * into/away from MST mode - as the CRTC on the real DP connector and the CRTCs on the connector's
4440  * MST topology will never share the same &drm_encoder.
4441  *
4442  * This function takes care of this serialization issue, by checking a root MST connector's atomic
4443  * state to determine if it is about to have a modeset - and then pulling in the MST topology state
4444  * if so, along with adding any relevant CRTCs to &drm_dp_mst_topology_state.pending_crtc_mask.
4445  *
4446  * Drivers implementing MST must call this function from the
4447  * &drm_connector_helper_funcs.atomic_check hook of any physical DP &drm_connector capable of
4448  * driving MST sinks.
4449  *
4450  * Returns:
4451  * 0 on success, negative error code otherwise
4452  */
4453 int drm_dp_mst_root_conn_atomic_check(struct drm_connector_state *new_conn_state,
4454 				      struct drm_dp_mst_topology_mgr *mgr)
4455 {
4456 	struct drm_atomic_state *state = new_conn_state->state;
4457 	struct drm_connector_state *old_conn_state =
4458 		drm_atomic_get_old_connector_state(state, new_conn_state->connector);
4459 	struct drm_crtc_state *crtc_state;
4460 	struct drm_dp_mst_topology_state *mst_state = NULL;
4461 
4462 	if (new_conn_state->crtc) {
4463 		crtc_state = drm_atomic_get_new_crtc_state(state, new_conn_state->crtc);
4464 		if (crtc_state && drm_atomic_crtc_needs_modeset(crtc_state)) {
4465 			mst_state = drm_atomic_get_mst_topology_state(state, mgr);
4466 			if (IS_ERR(mst_state))
4467 				return PTR_ERR(mst_state);
4468 
4469 			mst_state->pending_crtc_mask |= drm_crtc_mask(new_conn_state->crtc);
4470 		}
4471 	}
4472 
4473 	if (old_conn_state->crtc) {
4474 		crtc_state = drm_atomic_get_new_crtc_state(state, old_conn_state->crtc);
4475 		if (crtc_state && drm_atomic_crtc_needs_modeset(crtc_state)) {
4476 			if (!mst_state) {
4477 				mst_state = drm_atomic_get_mst_topology_state(state, mgr);
4478 				if (IS_ERR(mst_state))
4479 					return PTR_ERR(mst_state);
4480 			}
4481 
4482 			mst_state->pending_crtc_mask |= drm_crtc_mask(old_conn_state->crtc);
4483 		}
4484 	}
4485 
4486 	return 0;
4487 }
4488 EXPORT_SYMBOL(drm_dp_mst_root_conn_atomic_check);
4489 
4490 /**
4491  * drm_dp_mst_update_slots() - updates the slot info depending on the DP ecoding format
4492  * @mst_state: mst_state to update
4493  * @link_encoding_cap: the ecoding format on the link
4494  */
4495 void drm_dp_mst_update_slots(struct drm_dp_mst_topology_state *mst_state, uint8_t link_encoding_cap)
4496 {
4497 	if (link_encoding_cap == DP_CAP_ANSI_128B132B) {
4498 		mst_state->total_avail_slots = 64;
4499 		mst_state->start_slot = 0;
4500 	} else {
4501 		mst_state->total_avail_slots = 63;
4502 		mst_state->start_slot = 1;
4503 	}
4504 
4505 	DRM_DEBUG_KMS("%s encoding format on mst_state 0x%p\n",
4506 		      (link_encoding_cap == DP_CAP_ANSI_128B132B) ? "128b/132b":"8b/10b",
4507 		      mst_state);
4508 }
4509 EXPORT_SYMBOL(drm_dp_mst_update_slots);
4510 
4511 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
4512 				     int id, u8 start_slot, u8 num_slots)
4513 {
4514 	u8 payload_alloc[3], status;
4515 	int ret;
4516 	int retries = 0;
4517 
4518 	drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
4519 			   DP_PAYLOAD_TABLE_UPDATED);
4520 
4521 	payload_alloc[0] = id;
4522 	payload_alloc[1] = start_slot;
4523 	payload_alloc[2] = num_slots;
4524 
4525 	ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
4526 	if (ret != 3) {
4527 		drm_dbg_kms(mgr->dev, "failed to write payload allocation %d\n", ret);
4528 		goto fail;
4529 	}
4530 
4531 retry:
4532 	ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
4533 	if (ret < 0) {
4534 		drm_dbg_kms(mgr->dev, "failed to read payload table status %d\n", ret);
4535 		goto fail;
4536 	}
4537 
4538 	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
4539 		retries++;
4540 		if (retries < 20) {
4541 			usleep_range(10000, 20000);
4542 			goto retry;
4543 		}
4544 		drm_dbg_kms(mgr->dev, "status not set after read payload table status %d\n",
4545 			    status);
4546 		ret = -EINVAL;
4547 		goto fail;
4548 	}
4549 	ret = 0;
4550 fail:
4551 	return ret;
4552 }
4553 
4554 static int do_get_act_status(struct drm_dp_aux *aux)
4555 {
4556 	int ret;
4557 	u8 status;
4558 
4559 	ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
4560 	if (ret < 0)
4561 		return ret;
4562 
4563 	return status;
4564 }
4565 
4566 /**
4567  * drm_dp_check_act_status() - Polls for ACT handled status.
4568  * @mgr: manager to use
4569  *
4570  * Tries waiting for the MST hub to finish updating it's payload table by
4571  * polling for the ACT handled bit for up to 3 seconds (yes-some hubs really
4572  * take that long).
4573  *
4574  * Returns:
4575  * 0 if the ACT was handled in time, negative error code on failure.
4576  */
4577 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
4578 {
4579 	/*
4580 	 * There doesn't seem to be any recommended retry count or timeout in
4581 	 * the MST specification. Since some hubs have been observed to take
4582 	 * over 1 second to update their payload allocations under certain
4583 	 * conditions, we use a rather large timeout value.
4584 	 */
4585 	const int timeout_ms = 3000;
4586 	int ret, status;
4587 
4588 	ret = readx_poll_timeout(do_get_act_status, mgr->aux, status,
4589 				 status & DP_PAYLOAD_ACT_HANDLED || status < 0,
4590 				 200, timeout_ms * USEC_PER_MSEC);
4591 	if (ret < 0 && status >= 0) {
4592 		drm_err(mgr->dev, "Failed to get ACT after %dms, last status: %02x\n",
4593 			timeout_ms, status);
4594 		return -EINVAL;
4595 	} else if (status < 0) {
4596 		/*
4597 		 * Failure here isn't unexpected - the hub may have
4598 		 * just been unplugged
4599 		 */
4600 		drm_dbg_kms(mgr->dev, "Failed to read payload table status: %d\n", status);
4601 		return status;
4602 	}
4603 
4604 	return 0;
4605 }
4606 EXPORT_SYMBOL(drm_dp_check_act_status);
4607 
4608 /**
4609  * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
4610  * @clock: dot clock for the mode
4611  * @bpp: bpp for the mode.
4612  * @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel
4613  *
4614  * This uses the formula in the spec to calculate the PBN value for a mode.
4615  */
4616 int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
4617 {
4618 	/*
4619 	 * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
4620 	 * The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on
4621 	 * common multiplier to render an integer PBN for all link rate/lane
4622 	 * counts combinations
4623 	 * calculate
4624 	 * peak_kbps *= (1006/1000)
4625 	 * peak_kbps *= (64/54)
4626 	 * peak_kbps *= 8    convert to bytes
4627 	 *
4628 	 * If the bpp is in units of 1/16, further divide by 16. Put this
4629 	 * factor in the numerator rather than the denominator to avoid
4630 	 * integer overflow
4631 	 */
4632 
4633 	if (dsc)
4634 		return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006),
4635 					8 * 54 * 1000 * 1000);
4636 
4637 	return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006),
4638 				8 * 54 * 1000 * 1000);
4639 }
4640 EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
4641 
4642 /* we want to kick the TX after we've ack the up/down IRQs. */
4643 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
4644 {
4645 	queue_work(system_long_wq, &mgr->tx_work);
4646 }
4647 
4648 /*
4649  * Helper function for parsing DP device types into convenient strings
4650  * for use with dp_mst_topology
4651  */
4652 static const char *pdt_to_string(u8 pdt)
4653 {
4654 	switch (pdt) {
4655 	case DP_PEER_DEVICE_NONE:
4656 		return "NONE";
4657 	case DP_PEER_DEVICE_SOURCE_OR_SST:
4658 		return "SOURCE OR SST";
4659 	case DP_PEER_DEVICE_MST_BRANCHING:
4660 		return "MST BRANCHING";
4661 	case DP_PEER_DEVICE_SST_SINK:
4662 		return "SST SINK";
4663 	case DP_PEER_DEVICE_DP_LEGACY_CONV:
4664 		return "DP LEGACY CONV";
4665 	default:
4666 		return "ERR";
4667 	}
4668 }
4669 
4670 static void drm_dp_mst_dump_mstb(struct seq_file *m,
4671 				 struct drm_dp_mst_branch *mstb)
4672 {
4673 	struct drm_dp_mst_port *port;
4674 	int tabs = mstb->lct;
4675 	char prefix[10];
4676 	int i;
4677 
4678 	for (i = 0; i < tabs; i++)
4679 		prefix[i] = '\t';
4680 	prefix[i] = '\0';
4681 
4682 	seq_printf(m, "%smstb - [%p]: num_ports: %d\n", prefix, mstb, mstb->num_ports);
4683 	list_for_each_entry(port, &mstb->ports, next) {
4684 		seq_printf(m, "%sport %d - [%p] (%s - %s): ddps: %d, ldps: %d, sdp: %d/%d, fec: %s, conn: %p\n",
4685 			   prefix,
4686 			   port->port_num,
4687 			   port,
4688 			   port->input ? "input" : "output",
4689 			   pdt_to_string(port->pdt),
4690 			   port->ddps,
4691 			   port->ldps,
4692 			   port->num_sdp_streams,
4693 			   port->num_sdp_stream_sinks,
4694 			   port->fec_capable ? "true" : "false",
4695 			   port->connector);
4696 		if (port->mstb)
4697 			drm_dp_mst_dump_mstb(m, port->mstb);
4698 	}
4699 }
4700 
4701 #define DP_PAYLOAD_TABLE_SIZE		64
4702 
4703 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
4704 				  char *buf)
4705 {
4706 	int i;
4707 
4708 	for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
4709 		if (drm_dp_dpcd_read(mgr->aux,
4710 				     DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
4711 				     &buf[i], 16) != 16)
4712 			return false;
4713 	}
4714 	return true;
4715 }
4716 
4717 static void fetch_monitor_name(struct drm_dp_mst_topology_mgr *mgr,
4718 			       struct drm_dp_mst_port *port, char *name,
4719 			       int namelen)
4720 {
4721 	struct edid *mst_edid;
4722 
4723 	mst_edid = drm_dp_mst_get_edid(port->connector, mgr, port);
4724 	drm_edid_get_monitor_name(mst_edid, name, namelen);
4725 	kfree(mst_edid);
4726 }
4727 
4728 /**
4729  * drm_dp_mst_dump_topology(): dump topology to seq file.
4730  * @m: seq_file to dump output to
4731  * @mgr: manager to dump current topology for.
4732  *
4733  * helper to dump MST topology to a seq file for debugfs.
4734  */
4735 void drm_dp_mst_dump_topology(struct seq_file *m,
4736 			      struct drm_dp_mst_topology_mgr *mgr)
4737 {
4738 	struct drm_dp_mst_topology_state *state;
4739 	struct drm_dp_mst_atomic_payload *payload;
4740 	int i, ret;
4741 
4742 	mutex_lock(&mgr->lock);
4743 	if (mgr->mst_primary)
4744 		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
4745 
4746 	/* dump VCPIs */
4747 	mutex_unlock(&mgr->lock);
4748 
4749 	ret = drm_modeset_lock_single_interruptible(&mgr->base.lock);
4750 	if (ret < 0)
4751 		return;
4752 
4753 	state = to_drm_dp_mst_topology_state(mgr->base.state);
4754 	seq_printf(m, "\n*** Atomic state info ***\n");
4755 	seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u, pbn_div: %d\n",
4756 		   state->payload_mask, mgr->max_payloads, state->start_slot, state->pbn_div);
4757 
4758 	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name     |\n");
4759 	for (i = 0; i < mgr->max_payloads; i++) {
4760 		list_for_each_entry(payload, &state->payloads, next) {
4761 			char name[14];
4762 
4763 			if (payload->vcpi != i || payload->delete)
4764 				continue;
4765 
4766 			fetch_monitor_name(mgr, payload->port, name, sizeof(name));
4767 			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %19s\n",
4768 				   i,
4769 				   payload->port->port_num,
4770 				   payload->vcpi,
4771 				   payload->vc_start_slot,
4772 				   payload->vc_start_slot + payload->time_slots - 1,
4773 				   payload->pbn,
4774 				   payload->dsc_enabled ? "Y" : "N",
4775 				   (*name != 0) ? name : "Unknown");
4776 		}
4777 	}
4778 
4779 	seq_printf(m, "\n*** DPCD Info ***\n");
4780 	mutex_lock(&mgr->lock);
4781 	if (mgr->mst_primary) {
4782 		u8 buf[DP_PAYLOAD_TABLE_SIZE];
4783 		int ret;
4784 
4785 		if (drm_dp_read_dpcd_caps(mgr->aux, buf) < 0) {
4786 			seq_printf(m, "dpcd read failed\n");
4787 			goto out;
4788 		}
4789 		seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);
4790 
4791 		ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
4792 		if (ret != 2) {
4793 			seq_printf(m, "faux/mst read failed\n");
4794 			goto out;
4795 		}
4796 		seq_printf(m, "faux/mst: %*ph\n", 2, buf);
4797 
4798 		ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
4799 		if (ret != 1) {
4800 			seq_printf(m, "mst ctrl read failed\n");
4801 			goto out;
4802 		}
4803 		seq_printf(m, "mst ctrl: %*ph\n", 1, buf);
4804 
4805 		/* dump the standard OUI branch header */
4806 		ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf, DP_BRANCH_OUI_HEADER_SIZE);
4807 		if (ret != DP_BRANCH_OUI_HEADER_SIZE) {
4808 			seq_printf(m, "branch oui read failed\n");
4809 			goto out;
4810 		}
4811 		seq_printf(m, "branch oui: %*phN devid: ", 3, buf);
4812 
4813 		for (i = 0x3; i < 0x8 && buf[i]; i++)
4814 			seq_printf(m, "%c", buf[i]);
4815 		seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
4816 			   buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
4817 		if (dump_dp_payload_table(mgr, buf))
4818 			seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
4819 	}
4820 
4821 out:
4822 	mutex_unlock(&mgr->lock);
4823 	drm_modeset_unlock(&mgr->base.lock);
4824 }
4825 EXPORT_SYMBOL(drm_dp_mst_dump_topology);
4826 
4827 static void drm_dp_tx_work(struct work_struct *work)
4828 {
4829 	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, tx_work);
4830 
4831 	mutex_lock(&mgr->qlock);
4832 	if (!list_empty(&mgr->tx_msg_downq))
4833 		process_single_down_tx_qlock(mgr);
4834 	mutex_unlock(&mgr->qlock);
4835 }
4836 
4837 static inline void
4838 drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port)
4839 {
4840 	drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE, port->mcs);
4841 
4842 	if (port->connector) {
4843 		drm_connector_unregister(port->connector);
4844 		drm_connector_put(port->connector);
4845 	}
4846 
4847 	drm_dp_mst_put_port_malloc(port);
4848 }
4849 
4850 static inline void
4851 drm_dp_delayed_destroy_mstb(struct drm_dp_mst_branch *mstb)
4852 {
4853 	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
4854 	struct drm_dp_mst_port *port, *port_tmp;
4855 	struct drm_dp_sideband_msg_tx *txmsg, *txmsg_tmp;
4856 	bool wake_tx = false;
4857 
4858 	mutex_lock(&mgr->lock);
4859 	list_for_each_entry_safe(port, port_tmp, &mstb->ports, next) {
4860 		list_del(&port->next);
4861 		drm_dp_mst_topology_put_port(port);
4862 	}
4863 	mutex_unlock(&mgr->lock);
4864 
4865 	/* drop any tx slot msg */
4866 	mutex_lock(&mstb->mgr->qlock);
4867 	list_for_each_entry_safe(txmsg, txmsg_tmp, &mgr->tx_msg_downq, next) {
4868 		if (txmsg->dst != mstb)
4869 			continue;
4870 
4871 		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
4872 		list_del(&txmsg->next);
4873 		wake_tx = true;
4874 	}
4875 	mutex_unlock(&mstb->mgr->qlock);
4876 
4877 	if (wake_tx)
4878 		wake_up_all(&mstb->mgr->tx_waitq);
4879 
4880 	drm_dp_mst_put_mstb_malloc(mstb);
4881 }
4882 
4883 static void drm_dp_delayed_destroy_work(struct work_struct *work)
4884 {
4885 	struct drm_dp_mst_topology_mgr *mgr =
4886 		container_of(work, struct drm_dp_mst_topology_mgr,
4887 			     delayed_destroy_work);
4888 	bool send_hotplug = false, go_again;
4889 
4890 	/*
4891 	 * Not a regular list traverse as we have to drop the destroy
4892 	 * connector lock before destroying the mstb/port, to avoid AB->BA
4893 	 * ordering between this lock and the config mutex.
4894 	 */
4895 	do {
4896 		go_again = false;
4897 
4898 		for (;;) {
4899 			struct drm_dp_mst_branch *mstb;
4900 
4901 			mutex_lock(&mgr->delayed_destroy_lock);
4902 			mstb = list_first_entry_or_null(&mgr->destroy_branch_device_list,
4903 							struct drm_dp_mst_branch,
4904 							destroy_next);
4905 			if (mstb)
4906 				list_del(&mstb->destroy_next);
4907 			mutex_unlock(&mgr->delayed_destroy_lock);
4908 
4909 			if (!mstb)
4910 				break;
4911 
4912 			drm_dp_delayed_destroy_mstb(mstb);
4913 			go_again = true;
4914 		}
4915 
4916 		for (;;) {
4917 			struct drm_dp_mst_port *port;
4918 
4919 			mutex_lock(&mgr->delayed_destroy_lock);
4920 			port = list_first_entry_or_null(&mgr->destroy_port_list,
4921 							struct drm_dp_mst_port,
4922 							next);
4923 			if (port)
4924 				list_del(&port->next);
4925 			mutex_unlock(&mgr->delayed_destroy_lock);
4926 
4927 			if (!port)
4928 				break;
4929 
4930 			drm_dp_delayed_destroy_port(port);
4931 			send_hotplug = true;
4932 			go_again = true;
4933 		}
4934 	} while (go_again);
4935 
4936 	if (send_hotplug)
4937 		drm_kms_helper_hotplug_event(mgr->dev);
4938 }
4939 
4940 static struct drm_private_state *
4941 drm_dp_mst_duplicate_state(struct drm_private_obj *obj)
4942 {
4943 	struct drm_dp_mst_topology_state *state, *old_state =
4944 		to_dp_mst_topology_state(obj->state);
4945 	struct drm_dp_mst_atomic_payload *pos, *payload;
4946 
4947 	state = kmemdup(old_state, sizeof(*state), GFP_KERNEL);
4948 	if (!state)
4949 		return NULL;
4950 
4951 	__drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
4952 
4953 	INIT_LIST_HEAD(&state->payloads);
4954 	state->commit_deps = NULL;
4955 	state->num_commit_deps = 0;
4956 	state->pending_crtc_mask = 0;
4957 
4958 	list_for_each_entry(pos, &old_state->payloads, next) {
4959 		/* Prune leftover freed timeslot allocations */
4960 		if (pos->delete)
4961 			continue;
4962 
4963 		payload = kmemdup(pos, sizeof(*payload), GFP_KERNEL);
4964 		if (!payload)
4965 			goto fail;
4966 
4967 		drm_dp_mst_get_port_malloc(payload->port);
4968 		list_add(&payload->next, &state->payloads);
4969 	}
4970 
4971 	return &state->base;
4972 
4973 fail:
4974 	list_for_each_entry_safe(pos, payload, &state->payloads, next) {
4975 		drm_dp_mst_put_port_malloc(pos->port);
4976 		kfree(pos);
4977 	}
4978 	kfree(state);
4979 
4980 	return NULL;
4981 }
4982 
4983 static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
4984 				     struct drm_private_state *state)
4985 {
4986 	struct drm_dp_mst_topology_state *mst_state =
4987 		to_dp_mst_topology_state(state);
4988 	struct drm_dp_mst_atomic_payload *pos, *tmp;
4989 	int i;
4990 
4991 	list_for_each_entry_safe(pos, tmp, &mst_state->payloads, next) {
4992 		/* We only keep references to ports with active payloads */
4993 		if (!pos->delete)
4994 			drm_dp_mst_put_port_malloc(pos->port);
4995 		kfree(pos);
4996 	}
4997 
4998 	for (i = 0; i < mst_state->num_commit_deps; i++)
4999 		drm_crtc_commit_put(mst_state->commit_deps[i]);
5000 
5001 	kfree(mst_state->commit_deps);
5002 	kfree(mst_state);
5003 }
5004 
5005 static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
5006 						 struct drm_dp_mst_branch *branch)
5007 {
5008 	while (port->parent) {
5009 		if (port->parent == branch)
5010 			return true;
5011 
5012 		if (port->parent->port_parent)
5013 			port = port->parent->port_parent;
5014 		else
5015 			break;
5016 	}
5017 	return false;
5018 }
5019 
5020 static int
5021 drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
5022 				      struct drm_dp_mst_topology_state *state);
5023 
5024 static int
5025 drm_dp_mst_atomic_check_mstb_bw_limit(struct drm_dp_mst_branch *mstb,
5026 				      struct drm_dp_mst_topology_state *state)
5027 {
5028 	struct drm_dp_mst_atomic_payload *payload;
5029 	struct drm_dp_mst_port *port;
5030 	int pbn_used = 0, ret;
5031 	bool found = false;
5032 
5033 	/* Check that we have at least one port in our state that's downstream
5034 	 * of this branch, otherwise we can skip this branch
5035 	 */
5036 	list_for_each_entry(payload, &state->payloads, next) {
5037 		if (!payload->pbn ||
5038 		    !drm_dp_mst_port_downstream_of_branch(payload->port, mstb))
5039 			continue;
5040 
5041 		found = true;
5042 		break;
5043 	}
5044 	if (!found)
5045 		return 0;
5046 
5047 	if (mstb->port_parent)
5048 		drm_dbg_atomic(mstb->mgr->dev,
5049 			       "[MSTB:%p] [MST PORT:%p] Checking bandwidth limits on [MSTB:%p]\n",
5050 			       mstb->port_parent->parent, mstb->port_parent, mstb);
5051 	else
5052 		drm_dbg_atomic(mstb->mgr->dev, "[MSTB:%p] Checking bandwidth limits\n", mstb);
5053 
5054 	list_for_each_entry(port, &mstb->ports, next) {
5055 		ret = drm_dp_mst_atomic_check_port_bw_limit(port, state);
5056 		if (ret < 0)
5057 			return ret;
5058 
5059 		pbn_used += ret;
5060 	}
5061 
5062 	return pbn_used;
5063 }
5064 
5065 static int
5066 drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
5067 				      struct drm_dp_mst_topology_state *state)
5068 {
5069 	struct drm_dp_mst_atomic_payload *payload;
5070 	int pbn_used = 0;
5071 
5072 	if (port->pdt == DP_PEER_DEVICE_NONE)
5073 		return 0;
5074 
5075 	if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
5076 		payload = drm_atomic_get_mst_payload_state(state, port);
5077 		if (!payload)
5078 			return 0;
5079 
5080 		/*
5081 		 * This could happen if the sink deasserted its HPD line, but
5082 		 * the branch device still reports it as attached (PDT != NONE).
5083 		 */
5084 		if (!port->full_pbn) {
5085 			drm_dbg_atomic(port->mgr->dev,
5086 				       "[MSTB:%p] [MST PORT:%p] no BW available for the port\n",
5087 				       port->parent, port);
5088 			return -EINVAL;
5089 		}
5090 
5091 		pbn_used = payload->pbn;
5092 	} else {
5093 		pbn_used = drm_dp_mst_atomic_check_mstb_bw_limit(port->mstb,
5094 								 state);
5095 		if (pbn_used <= 0)
5096 			return pbn_used;
5097 	}
5098 
5099 	if (pbn_used > port->full_pbn) {
5100 		drm_dbg_atomic(port->mgr->dev,
5101 			       "[MSTB:%p] [MST PORT:%p] required PBN of %d exceeds port limit of %d\n",
5102 			       port->parent, port, pbn_used, port->full_pbn);
5103 		return -ENOSPC;
5104 	}
5105 
5106 	drm_dbg_atomic(port->mgr->dev, "[MSTB:%p] [MST PORT:%p] uses %d out of %d PBN\n",
5107 		       port->parent, port, pbn_used, port->full_pbn);
5108 
5109 	return pbn_used;
5110 }
5111 
5112 static inline int
5113 drm_dp_mst_atomic_check_payload_alloc_limits(struct drm_dp_mst_topology_mgr *mgr,
5114 					     struct drm_dp_mst_topology_state *mst_state)
5115 {
5116 	struct drm_dp_mst_atomic_payload *payload;
5117 	int avail_slots = mst_state->total_avail_slots, payload_count = 0;
5118 
5119 	list_for_each_entry(payload, &mst_state->payloads, next) {
5120 		/* Releasing payloads is always OK-even if the port is gone */
5121 		if (payload->delete) {
5122 			drm_dbg_atomic(mgr->dev, "[MST PORT:%p] releases all time slots\n",
5123 				       payload->port);
5124 			continue;
5125 		}
5126 
5127 		drm_dbg_atomic(mgr->dev, "[MST PORT:%p] requires %d time slots\n",
5128 			       payload->port, payload->time_slots);
5129 
5130 		avail_slots -= payload->time_slots;
5131 		if (avail_slots < 0) {
5132 			drm_dbg_atomic(mgr->dev,
5133 				       "[MST PORT:%p] not enough time slots in mst state %p (avail=%d)\n",
5134 				       payload->port, mst_state, avail_slots + payload->time_slots);
5135 			return -ENOSPC;
5136 		}
5137 
5138 		if (++payload_count > mgr->max_payloads) {
5139 			drm_dbg_atomic(mgr->dev,
5140 				       "[MST MGR:%p] state %p has too many payloads (max=%d)\n",
5141 				       mgr, mst_state, mgr->max_payloads);
5142 			return -EINVAL;
5143 		}
5144 
5145 		/* Assign a VCPI */
5146 		if (!payload->vcpi) {
5147 			payload->vcpi = ffz(mst_state->payload_mask) + 1;
5148 			drm_dbg_atomic(mgr->dev, "[MST PORT:%p] assigned VCPI #%d\n",
5149 				       payload->port, payload->vcpi);
5150 			mst_state->payload_mask |= BIT(payload->vcpi - 1);
5151 		}
5152 	}
5153 
5154 	if (!payload_count)
5155 		mst_state->pbn_div = 0;
5156 
5157 	drm_dbg_atomic(mgr->dev, "[MST MGR:%p] mst state %p TU pbn_div=%d avail=%d used=%d\n",
5158 		       mgr, mst_state, mst_state->pbn_div, avail_slots,
5159 		       mst_state->total_avail_slots - avail_slots);
5160 
5161 	return 0;
5162 }
5163 
5164 /**
5165  * drm_dp_mst_add_affected_dsc_crtcs
5166  * @state: Pointer to the new struct drm_dp_mst_topology_state
5167  * @mgr: MST topology manager
5168  *
5169  * Whenever there is a change in mst topology
5170  * DSC configuration would have to be recalculated
5171  * therefore we need to trigger modeset on all affected
5172  * CRTCs in that topology
5173  *
5174  * See also:
5175  * drm_dp_mst_atomic_enable_dsc()
5176  */
5177 int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state, struct drm_dp_mst_topology_mgr *mgr)
5178 {
5179 	struct drm_dp_mst_topology_state *mst_state;
5180 	struct drm_dp_mst_atomic_payload *pos;
5181 	struct drm_connector *connector;
5182 	struct drm_connector_state *conn_state;
5183 	struct drm_crtc *crtc;
5184 	struct drm_crtc_state *crtc_state;
5185 
5186 	mst_state = drm_atomic_get_mst_topology_state(state, mgr);
5187 
5188 	if (IS_ERR(mst_state))
5189 		return PTR_ERR(mst_state);
5190 
5191 	list_for_each_entry(pos, &mst_state->payloads, next) {
5192 
5193 		connector = pos->port->connector;
5194 
5195 		if (!connector)
5196 			return -EINVAL;
5197 
5198 		conn_state = drm_atomic_get_connector_state(state, connector);
5199 
5200 		if (IS_ERR(conn_state))
5201 			return PTR_ERR(conn_state);
5202 
5203 		crtc = conn_state->crtc;
5204 
5205 		if (!crtc)
5206 			continue;
5207 
5208 		if (!drm_dp_mst_dsc_aux_for_port(pos->port))
5209 			continue;
5210 
5211 		crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
5212 
5213 		if (IS_ERR(crtc_state))
5214 			return PTR_ERR(crtc_state);
5215 
5216 		drm_dbg_atomic(mgr->dev, "[MST MGR:%p] Setting mode_changed flag on CRTC %p\n",
5217 			       mgr, crtc);
5218 
5219 		crtc_state->mode_changed = true;
5220 	}
5221 	return 0;
5222 }
5223 EXPORT_SYMBOL(drm_dp_mst_add_affected_dsc_crtcs);
5224 
5225 /**
5226  * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
5227  * @state: Pointer to the new drm_atomic_state
5228  * @port: Pointer to the affected MST Port
5229  * @pbn: Newly recalculated bw required for link with DSC enabled
5230  * @enable: Boolean flag to enable or disable DSC on the port
5231  *
5232  * This function enables DSC on the given Port
5233  * by recalculating its vcpi from pbn provided
5234  * and sets dsc_enable flag to keep track of which
5235  * ports have DSC enabled
5236  *
5237  */
5238 int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
5239 				 struct drm_dp_mst_port *port,
5240 				 int pbn, bool enable)
5241 {
5242 	struct drm_dp_mst_topology_state *mst_state;
5243 	struct drm_dp_mst_atomic_payload *payload;
5244 	int time_slots = 0;
5245 
5246 	mst_state = drm_atomic_get_mst_topology_state(state, port->mgr);
5247 	if (IS_ERR(mst_state))
5248 		return PTR_ERR(mst_state);
5249 
5250 	payload = drm_atomic_get_mst_payload_state(mst_state, port);
5251 	if (!payload) {
5252 		drm_dbg_atomic(state->dev,
5253 			       "[MST PORT:%p] Couldn't find payload in mst state %p\n",
5254 			       port, mst_state);
5255 		return -EINVAL;
5256 	}
5257 
5258 	if (payload->dsc_enabled == enable) {
5259 		drm_dbg_atomic(state->dev,
5260 			       "[MST PORT:%p] DSC flag is already set to %d, returning %d time slots\n",
5261 			       port, enable, payload->time_slots);
5262 		time_slots = payload->time_slots;
5263 	}
5264 
5265 	if (enable) {
5266 		time_slots = drm_dp_atomic_find_time_slots(state, port->mgr, port, pbn);
5267 		drm_dbg_atomic(state->dev,
5268 			       "[MST PORT:%p] Enabling DSC flag, reallocating %d time slots on the port\n",
5269 			       port, time_slots);
5270 		if (time_slots < 0)
5271 			return -EINVAL;
5272 	}
5273 
5274 	payload->dsc_enabled = enable;
5275 
5276 	return time_slots;
5277 }
5278 EXPORT_SYMBOL(drm_dp_mst_atomic_enable_dsc);
5279 
5280 /**
5281  * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
5282  * atomic update is valid
5283  * @state: Pointer to the new &struct drm_dp_mst_topology_state
5284  *
5285  * Checks the given topology state for an atomic update to ensure that it's
5286  * valid. This includes checking whether there's enough bandwidth to support
5287  * the new timeslot allocations in the atomic update.
5288  *
5289  * Any atomic drivers supporting DP MST must make sure to call this after
5290  * checking the rest of their state in their
5291  * &drm_mode_config_funcs.atomic_check() callback.
5292  *
5293  * See also:
5294  * drm_dp_atomic_find_time_slots()
5295  * drm_dp_atomic_release_time_slots()
5296  *
5297  * Returns:
5298  *
5299  * 0 if the new state is valid, negative error code otherwise.
5300  */
5301 int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
5302 {
5303 	struct drm_dp_mst_topology_mgr *mgr;
5304 	struct drm_dp_mst_topology_state *mst_state;
5305 	int i, ret = 0;
5306 
5307 	for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
5308 		if (!mgr->mst_state)
5309 			continue;
5310 
5311 		ret = drm_dp_mst_atomic_check_payload_alloc_limits(mgr, mst_state);
5312 		if (ret)
5313 			break;
5314 
5315 		mutex_lock(&mgr->lock);
5316 		ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,
5317 							    mst_state);
5318 		mutex_unlock(&mgr->lock);
5319 		if (ret < 0)
5320 			break;
5321 		else
5322 			ret = 0;
5323 	}
5324 
5325 	return ret;
5326 }
5327 EXPORT_SYMBOL(drm_dp_mst_atomic_check);
5328 
5329 const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs = {
5330 	.atomic_duplicate_state = drm_dp_mst_duplicate_state,
5331 	.atomic_destroy_state = drm_dp_mst_destroy_state,
5332 };
5333 EXPORT_SYMBOL(drm_dp_mst_topology_state_funcs);
5334 
5335 /**
5336  * drm_atomic_get_mst_topology_state: get MST topology state
5337  * @state: global atomic state
5338  * @mgr: MST topology manager, also the private object in this case
5339  *
5340  * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
5341  * state vtable so that the private object state returned is that of a MST
5342  * topology object.
5343  *
5344  * RETURNS:
5345  *
5346  * The MST topology state or error pointer.
5347  */
5348 struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
5349 								    struct drm_dp_mst_topology_mgr *mgr)
5350 {
5351 	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
5352 }
5353 EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
5354 
5355 /**
5356  * drm_atomic_get_new_mst_topology_state: get new MST topology state in atomic state, if any
5357  * @state: global atomic state
5358  * @mgr: MST topology manager, also the private object in this case
5359  *
5360  * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
5361  * state vtable so that the private object state returned is that of a MST
5362  * topology object.
5363  *
5364  * Returns:
5365  *
5366  * The MST topology state, or NULL if there's no topology state for this MST mgr
5367  * in the global atomic state
5368  */
5369 struct drm_dp_mst_topology_state *
5370 drm_atomic_get_new_mst_topology_state(struct drm_atomic_state *state,
5371 				      struct drm_dp_mst_topology_mgr *mgr)
5372 {
5373 	struct drm_private_state *priv_state =
5374 		drm_atomic_get_new_private_obj_state(state, &mgr->base);
5375 
5376 	return priv_state ? to_dp_mst_topology_state(priv_state) : NULL;
5377 }
5378 EXPORT_SYMBOL(drm_atomic_get_new_mst_topology_state);
5379 
5380 /**
5381  * drm_dp_mst_topology_mgr_init - initialise a topology manager
5382  * @mgr: manager struct to initialise
5383  * @dev: device providing this structure - for i2c addition.
5384  * @aux: DP helper aux channel to talk to this device
5385  * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
5386  * @max_payloads: maximum number of payloads this GPU can source
5387  * @conn_base_id: the connector object ID the MST device is connected to.
5388  *
5389  * Return 0 for success, or negative error code on failure
5390  */
5391 int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
5392 				 struct drm_device *dev, struct drm_dp_aux *aux,
5393 				 int max_dpcd_transaction_bytes, int max_payloads,
5394 				 int conn_base_id)
5395 {
5396 	struct drm_dp_mst_topology_state *mst_state;
5397 
5398 	mutex_init(&mgr->lock);
5399 	mutex_init(&mgr->qlock);
5400 	mutex_init(&mgr->delayed_destroy_lock);
5401 	mutex_init(&mgr->up_req_lock);
5402 	mutex_init(&mgr->probe_lock);
5403 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
5404 	mutex_init(&mgr->topology_ref_history_lock);
5405 	stack_depot_init();
5406 #endif
5407 	INIT_LIST_HEAD(&mgr->tx_msg_downq);
5408 	INIT_LIST_HEAD(&mgr->destroy_port_list);
5409 	INIT_LIST_HEAD(&mgr->destroy_branch_device_list);
5410 	INIT_LIST_HEAD(&mgr->up_req_list);
5411 
5412 	/*
5413 	 * delayed_destroy_work will be queued on a dedicated WQ, so that any
5414 	 * requeuing will be also flushed when deiniting the topology manager.
5415 	 */
5416 	mgr->delayed_destroy_wq = alloc_ordered_workqueue("drm_dp_mst_wq", 0);
5417 	if (mgr->delayed_destroy_wq == NULL)
5418 		return -ENOMEM;
5419 
5420 	INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
5421 	INIT_WORK(&mgr->tx_work, drm_dp_tx_work);
5422 	INIT_WORK(&mgr->delayed_destroy_work, drm_dp_delayed_destroy_work);
5423 	INIT_WORK(&mgr->up_req_work, drm_dp_mst_up_req_work);
5424 	init_waitqueue_head(&mgr->tx_waitq);
5425 	mgr->dev = dev;
5426 	mgr->aux = aux;
5427 	mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
5428 	mgr->max_payloads = max_payloads;
5429 	mgr->conn_base_id = conn_base_id;
5430 
5431 	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
5432 	if (mst_state == NULL)
5433 		return -ENOMEM;
5434 
5435 	mst_state->total_avail_slots = 63;
5436 	mst_state->start_slot = 1;
5437 
5438 	mst_state->mgr = mgr;
5439 	INIT_LIST_HEAD(&mst_state->payloads);
5440 
5441 	drm_atomic_private_obj_init(dev, &mgr->base,
5442 				    &mst_state->base,
5443 				    &drm_dp_mst_topology_state_funcs);
5444 
5445 	return 0;
5446 }
5447 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
5448 
5449 /**
5450  * drm_dp_mst_topology_mgr_destroy() - destroy topology manager.
5451  * @mgr: manager to destroy
5452  */
5453 void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
5454 {
5455 	drm_dp_mst_topology_mgr_set_mst(mgr, false);
5456 	flush_work(&mgr->work);
5457 	/* The following will also drain any requeued work on the WQ. */
5458 	if (mgr->delayed_destroy_wq) {
5459 		destroy_workqueue(mgr->delayed_destroy_wq);
5460 		mgr->delayed_destroy_wq = NULL;
5461 	}
5462 	mgr->dev = NULL;
5463 	mgr->aux = NULL;
5464 	drm_atomic_private_obj_fini(&mgr->base);
5465 	mgr->funcs = NULL;
5466 
5467 	mutex_destroy(&mgr->delayed_destroy_lock);
5468 	mutex_destroy(&mgr->qlock);
5469 	mutex_destroy(&mgr->lock);
5470 	mutex_destroy(&mgr->up_req_lock);
5471 	mutex_destroy(&mgr->probe_lock);
5472 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
5473 	mutex_destroy(&mgr->topology_ref_history_lock);
5474 #endif
5475 }
5476 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
5477 
5478 static bool remote_i2c_read_ok(const struct i2c_msg msgs[], int num)
5479 {
5480 	int i;
5481 
5482 	if (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)
5483 		return false;
5484 
5485 	for (i = 0; i < num - 1; i++) {
5486 		if (msgs[i].flags & I2C_M_RD ||
5487 		    msgs[i].len > 0xff)
5488 			return false;
5489 	}
5490 
5491 	return msgs[num - 1].flags & I2C_M_RD &&
5492 		msgs[num - 1].len <= 0xff;
5493 }
5494 
5495 static bool remote_i2c_write_ok(const struct i2c_msg msgs[], int num)
5496 {
5497 	int i;
5498 
5499 	for (i = 0; i < num - 1; i++) {
5500 		if (msgs[i].flags & I2C_M_RD || !(msgs[i].flags & I2C_M_STOP) ||
5501 		    msgs[i].len > 0xff)
5502 			return false;
5503 	}
5504 
5505 	return !(msgs[num - 1].flags & I2C_M_RD) && msgs[num - 1].len <= 0xff;
5506 }
5507 
5508 static int drm_dp_mst_i2c_read(struct drm_dp_mst_branch *mstb,
5509 			       struct drm_dp_mst_port *port,
5510 			       struct i2c_msg *msgs, int num)
5511 {
5512 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5513 	unsigned int i;
5514 	struct drm_dp_sideband_msg_req_body msg;
5515 	struct drm_dp_sideband_msg_tx *txmsg = NULL;
5516 	int ret;
5517 
5518 	memset(&msg, 0, sizeof(msg));
5519 	msg.req_type = DP_REMOTE_I2C_READ;
5520 	msg.u.i2c_read.num_transactions = num - 1;
5521 	msg.u.i2c_read.port_number = port->port_num;
5522 	for (i = 0; i < num - 1; i++) {
5523 		msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
5524 		msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
5525 		msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
5526 		msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP);
5527 	}
5528 	msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
5529 	msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
5530 
5531 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
5532 	if (!txmsg) {
5533 		ret = -ENOMEM;
5534 		goto out;
5535 	}
5536 
5537 	txmsg->dst = mstb;
5538 	drm_dp_encode_sideband_req(&msg, txmsg);
5539 
5540 	drm_dp_queue_down_tx(mgr, txmsg);
5541 
5542 	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
5543 	if (ret > 0) {
5544 
5545 		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
5546 			ret = -EREMOTEIO;
5547 			goto out;
5548 		}
5549 		if (txmsg->reply.u.remote_i2c_read_ack.num_bytes != msgs[num - 1].len) {
5550 			ret = -EIO;
5551 			goto out;
5552 		}
5553 		memcpy(msgs[num - 1].buf, txmsg->reply.u.remote_i2c_read_ack.bytes, msgs[num - 1].len);
5554 		ret = num;
5555 	}
5556 out:
5557 	kfree(txmsg);
5558 	return ret;
5559 }
5560 
5561 static int drm_dp_mst_i2c_write(struct drm_dp_mst_branch *mstb,
5562 				struct drm_dp_mst_port *port,
5563 				struct i2c_msg *msgs, int num)
5564 {
5565 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5566 	unsigned int i;
5567 	struct drm_dp_sideband_msg_req_body msg;
5568 	struct drm_dp_sideband_msg_tx *txmsg = NULL;
5569 	int ret;
5570 
5571 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
5572 	if (!txmsg) {
5573 		ret = -ENOMEM;
5574 		goto out;
5575 	}
5576 	for (i = 0; i < num; i++) {
5577 		memset(&msg, 0, sizeof(msg));
5578 		msg.req_type = DP_REMOTE_I2C_WRITE;
5579 		msg.u.i2c_write.port_number = port->port_num;
5580 		msg.u.i2c_write.write_i2c_device_id = msgs[i].addr;
5581 		msg.u.i2c_write.num_bytes = msgs[i].len;
5582 		msg.u.i2c_write.bytes = msgs[i].buf;
5583 
5584 		memset(txmsg, 0, sizeof(*txmsg));
5585 		txmsg->dst = mstb;
5586 
5587 		drm_dp_encode_sideband_req(&msg, txmsg);
5588 		drm_dp_queue_down_tx(mgr, txmsg);
5589 
5590 		ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
5591 		if (ret > 0) {
5592 			if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
5593 				ret = -EREMOTEIO;
5594 				goto out;
5595 			}
5596 		} else {
5597 			goto out;
5598 		}
5599 	}
5600 	ret = num;
5601 out:
5602 	kfree(txmsg);
5603 	return ret;
5604 }
5605 
5606 /* I2C device */
5607 static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter,
5608 			       struct i2c_msg *msgs, int num)
5609 {
5610 	struct drm_dp_aux *aux = adapter->algo_data;
5611 	struct drm_dp_mst_port *port =
5612 		container_of(aux, struct drm_dp_mst_port, aux);
5613 	struct drm_dp_mst_branch *mstb;
5614 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5615 	int ret;
5616 
5617 	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
5618 	if (!mstb)
5619 		return -EREMOTEIO;
5620 
5621 	if (remote_i2c_read_ok(msgs, num)) {
5622 		ret = drm_dp_mst_i2c_read(mstb, port, msgs, num);
5623 	} else if (remote_i2c_write_ok(msgs, num)) {
5624 		ret = drm_dp_mst_i2c_write(mstb, port, msgs, num);
5625 	} else {
5626 		drm_dbg_kms(mgr->dev, "Unsupported I2C transaction for MST device\n");
5627 		ret = -EIO;
5628 	}
5629 
5630 	drm_dp_mst_topology_put_mstb(mstb);
5631 	return ret;
5632 }
5633 
5634 static u32 drm_dp_mst_i2c_functionality(struct i2c_adapter *adapter)
5635 {
5636 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
5637 	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
5638 	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
5639 	       I2C_FUNC_10BIT_ADDR;
5640 }
5641 
5642 static const struct i2c_algorithm drm_dp_mst_i2c_algo = {
5643 	.functionality = drm_dp_mst_i2c_functionality,
5644 	.master_xfer = drm_dp_mst_i2c_xfer,
5645 };
5646 
5647 /**
5648  * drm_dp_mst_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
5649  * @port: The port to add the I2C bus on
5650  *
5651  * Returns 0 on success or a negative error code on failure.
5652  */
5653 static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port)
5654 {
5655 	struct drm_dp_aux *aux = &port->aux;
5656 	struct device *parent_dev = port->mgr->dev->dev;
5657 
5658 	aux->ddc.algo = &drm_dp_mst_i2c_algo;
5659 	aux->ddc.algo_data = aux;
5660 	aux->ddc.retries = 3;
5661 
5662 	aux->ddc.class = I2C_CLASS_DDC;
5663 	aux->ddc.owner = THIS_MODULE;
5664 	/* FIXME: set the kdev of the port's connector as parent */
5665 	aux->ddc.dev.parent = parent_dev;
5666 	aux->ddc.dev.of_node = parent_dev->of_node;
5667 
5668 	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(parent_dev),
5669 		sizeof(aux->ddc.name));
5670 
5671 	return i2c_add_adapter(&aux->ddc);
5672 }
5673 
5674 /**
5675  * drm_dp_mst_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
5676  * @port: The port to remove the I2C bus from
5677  */
5678 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port)
5679 {
5680 	i2c_del_adapter(&port->aux.ddc);
5681 }
5682 
5683 /**
5684  * drm_dp_mst_is_virtual_dpcd() - Is the given port a virtual DP Peer Device
5685  * @port: The port to check
5686  *
5687  * A single physical MST hub object can be represented in the topology
5688  * by multiple branches, with virtual ports between those branches.
5689  *
5690  * As of DP1.4, An MST hub with internal (virtual) ports must expose
5691  * certain DPCD registers over those ports. See sections 2.6.1.1.1
5692  * and 2.6.1.1.2 of Display Port specification v1.4 for details.
5693  *
5694  * May acquire mgr->lock
5695  *
5696  * Returns:
5697  * true if the port is a virtual DP peer device, false otherwise
5698  */
5699 static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port)
5700 {
5701 	struct drm_dp_mst_port *downstream_port;
5702 
5703 	if (!port || port->dpcd_rev < DP_DPCD_REV_14)
5704 		return false;
5705 
5706 	/* Virtual DP Sink (Internal Display Panel) */
5707 	if (port->port_num >= 8)
5708 		return true;
5709 
5710 	/* DP-to-HDMI Protocol Converter */
5711 	if (port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV &&
5712 	    !port->mcs &&
5713 	    port->ldps)
5714 		return true;
5715 
5716 	/* DP-to-DP */
5717 	mutex_lock(&port->mgr->lock);
5718 	if (port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
5719 	    port->mstb &&
5720 	    port->mstb->num_ports == 2) {
5721 		list_for_each_entry(downstream_port, &port->mstb->ports, next) {
5722 			if (downstream_port->pdt == DP_PEER_DEVICE_SST_SINK &&
5723 			    !downstream_port->input) {
5724 				mutex_unlock(&port->mgr->lock);
5725 				return true;
5726 			}
5727 		}
5728 	}
5729 	mutex_unlock(&port->mgr->lock);
5730 
5731 	return false;
5732 }
5733 
5734 /**
5735  * drm_dp_mst_dsc_aux_for_port() - Find the correct aux for DSC
5736  * @port: The port to check. A leaf of the MST tree with an attached display.
5737  *
5738  * Depending on the situation, DSC may be enabled via the endpoint aux,
5739  * the immediately upstream aux, or the connector's physical aux.
5740  *
5741  * This is both the correct aux to read DSC_CAPABILITY and the
5742  * correct aux to write DSC_ENABLED.
5743  *
5744  * This operation can be expensive (up to four aux reads), so
5745  * the caller should cache the return.
5746  *
5747  * Returns:
5748  * NULL if DSC cannot be enabled on this port, otherwise the aux device
5749  */
5750 struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
5751 {
5752 	struct drm_dp_mst_port *immediate_upstream_port;
5753 	struct drm_dp_mst_port *fec_port;
5754 	struct drm_dp_desc desc = {};
5755 	u8 endpoint_fec;
5756 	u8 endpoint_dsc;
5757 
5758 	if (!port)
5759 		return NULL;
5760 
5761 	if (port->parent->port_parent)
5762 		immediate_upstream_port = port->parent->port_parent;
5763 	else
5764 		immediate_upstream_port = NULL;
5765 
5766 	fec_port = immediate_upstream_port;
5767 	while (fec_port) {
5768 		/*
5769 		 * Each physical link (i.e. not a virtual port) between the
5770 		 * output and the primary device must support FEC
5771 		 */
5772 		if (!drm_dp_mst_is_virtual_dpcd(fec_port) &&
5773 		    !fec_port->fec_capable)
5774 			return NULL;
5775 
5776 		fec_port = fec_port->parent->port_parent;
5777 	}
5778 
5779 	/* DP-to-DP peer device */
5780 	if (drm_dp_mst_is_virtual_dpcd(immediate_upstream_port)) {
5781 		u8 upstream_dsc;
5782 
5783 		if (drm_dp_dpcd_read(&port->aux,
5784 				     DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
5785 			return NULL;
5786 		if (drm_dp_dpcd_read(&port->aux,
5787 				     DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
5788 			return NULL;
5789 		if (drm_dp_dpcd_read(&immediate_upstream_port->aux,
5790 				     DP_DSC_SUPPORT, &upstream_dsc, 1) != 1)
5791 			return NULL;
5792 
5793 		/* Enpoint decompression with DP-to-DP peer device */
5794 		if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
5795 		    (endpoint_fec & DP_FEC_CAPABLE) &&
5796 		    (upstream_dsc & DP_DSC_PASSTHROUGH_IS_SUPPORTED)) {
5797 			port->passthrough_aux = &immediate_upstream_port->aux;
5798 			return &port->aux;
5799 		}
5800 
5801 		/* Virtual DPCD decompression with DP-to-DP peer device */
5802 		return &immediate_upstream_port->aux;
5803 	}
5804 
5805 	/* Virtual DPCD decompression with DP-to-HDMI or Virtual DP Sink */
5806 	if (drm_dp_mst_is_virtual_dpcd(port))
5807 		return &port->aux;
5808 
5809 	/*
5810 	 * Synaptics quirk
5811 	 * Applies to ports for which:
5812 	 * - Physical aux has Synaptics OUI
5813 	 * - DPv1.4 or higher
5814 	 * - Port is on primary branch device
5815 	 * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
5816 	 */
5817 	if (drm_dp_read_desc(port->mgr->aux, &desc, true))
5818 		return NULL;
5819 
5820 	if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
5821 	    port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
5822 	    port->parent == port->mgr->mst_primary) {
5823 		u8 dpcd_ext[DP_RECEIVER_CAP_SIZE];
5824 
5825 		if (drm_dp_read_dpcd_caps(port->mgr->aux, dpcd_ext) < 0)
5826 			return NULL;
5827 
5828 		if ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT) &&
5829 		    ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK)
5830 		     != DP_DWN_STRM_PORT_TYPE_ANALOG))
5831 			return port->mgr->aux;
5832 	}
5833 
5834 	/*
5835 	 * The check below verifies if the MST sink
5836 	 * connected to the GPU is capable of DSC -
5837 	 * therefore the endpoint needs to be
5838 	 * both DSC and FEC capable.
5839 	 */
5840 	if (drm_dp_dpcd_read(&port->aux,
5841 	   DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
5842 		return NULL;
5843 	if (drm_dp_dpcd_read(&port->aux,
5844 	   DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
5845 		return NULL;
5846 	if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
5847 	   (endpoint_fec & DP_FEC_CAPABLE))
5848 		return &port->aux;
5849 
5850 	return NULL;
5851 }
5852 EXPORT_SYMBOL(drm_dp_mst_dsc_aux_for_port);
5853