1 /*
2  * Copyright 2012-15 Advanced Micro Devices, Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  * Authors: AMD
23  *
24  */
25 
26 #include <linux/delay.h>
27 #include <linux/slab.h>
28 
29 #include "dm_services.h"
30 #include "core_types.h"
31 #include "dce_aux.h"
32 #include "dce/dce_11_0_sh_mask.h"
33 #include "dm_event_log.h"
34 
35 #define CTX \
36 	aux110->base.ctx
37 #define REG(reg_name)\
38 	(aux110->regs->reg_name)
39 
40 #define DC_LOGGER \
41 	engine->ctx->logger
42 
43 #include "reg_helper.h"
44 
45 #undef FN
46 #define FN(reg_name, field_name) \
47 	aux110->shift->field_name, aux110->mask->field_name
48 
49 #define FROM_AUX_ENGINE(ptr) \
50 	container_of((ptr), struct aux_engine_dce110, base)
51 
52 #define FROM_ENGINE(ptr) \
53 	FROM_AUX_ENGINE(container_of((ptr), struct dce_aux, base))
54 
55 #define FROM_AUX_ENGINE_ENGINE(ptr) \
56 	container_of((ptr), struct dce_aux, base)
57 enum {
58 	AUX_INVALID_REPLY_RETRY_COUNTER = 1,
59 	AUX_TIMED_OUT_RETRY_COUNTER = 2,
60 	AUX_DEFER_RETRY_COUNTER = 6
61 };
62 
63 #define TIME_OUT_INCREMENT      1016
64 #define TIME_OUT_MULTIPLIER_8 	8
65 #define TIME_OUT_MULTIPLIER_16  16
66 #define TIME_OUT_MULTIPLIER_32  32
67 #define TIME_OUT_MULTIPLIER_64  64
68 #define MAX_TIMEOUT_LENGTH      127
69 
70 static void release_engine(
71 	struct dce_aux *engine)
72 {
73 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(engine);
74 
75 	dal_ddc_close(engine->ddc);
76 
77 	engine->ddc = NULL;
78 
79 	REG_UPDATE(AUX_ARB_CONTROL, AUX_SW_DONE_USING_AUX_REG, 1);
80 }
81 
82 #define SW_CAN_ACCESS_AUX 1
83 #define DMCU_CAN_ACCESS_AUX 2
84 
85 static bool is_engine_available(
86 	struct dce_aux *engine)
87 {
88 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(engine);
89 
90 	uint32_t value = REG_READ(AUX_ARB_CONTROL);
91 	uint32_t field = get_reg_field_value(
92 			value,
93 			AUX_ARB_CONTROL,
94 			AUX_REG_RW_CNTL_STATUS);
95 
96 	return (field != DMCU_CAN_ACCESS_AUX);
97 }
98 static bool acquire_engine(
99 	struct dce_aux *engine)
100 {
101 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(engine);
102 
103 	uint32_t value = REG_READ(AUX_ARB_CONTROL);
104 	uint32_t field = get_reg_field_value(
105 			value,
106 			AUX_ARB_CONTROL,
107 			AUX_REG_RW_CNTL_STATUS);
108 	if (field == DMCU_CAN_ACCESS_AUX)
109 		return false;
110 	/* enable AUX before request SW to access AUX */
111 	value = REG_READ(AUX_CONTROL);
112 	field = get_reg_field_value(value,
113 				AUX_CONTROL,
114 				AUX_EN);
115 
116 	if (field == 0) {
117 		set_reg_field_value(
118 				value,
119 				1,
120 				AUX_CONTROL,
121 				AUX_EN);
122 
123 		if (REG(AUX_RESET_MASK)) {
124 			/*DP_AUX block as part of the enable sequence*/
125 			set_reg_field_value(
126 				value,
127 				1,
128 				AUX_CONTROL,
129 				AUX_RESET);
130 		}
131 
132 		REG_WRITE(AUX_CONTROL, value);
133 
134 		if (REG(AUX_RESET_MASK)) {
135 			/*poll HW to make sure reset it done*/
136 
137 			REG_WAIT(AUX_CONTROL, AUX_RESET_DONE, 1,
138 					1, 11);
139 
140 			set_reg_field_value(
141 				value,
142 				0,
143 				AUX_CONTROL,
144 				AUX_RESET);
145 
146 			REG_WRITE(AUX_CONTROL, value);
147 
148 			REG_WAIT(AUX_CONTROL, AUX_RESET_DONE, 0,
149 					1, 11);
150 		}
151 	} /*if (field)*/
152 
153 	/* request SW to access AUX */
154 	REG_UPDATE(AUX_ARB_CONTROL, AUX_SW_USE_AUX_REG_REQ, 1);
155 
156 	value = REG_READ(AUX_ARB_CONTROL);
157 	field = get_reg_field_value(
158 			value,
159 			AUX_ARB_CONTROL,
160 			AUX_REG_RW_CNTL_STATUS);
161 
162 	return (field == SW_CAN_ACCESS_AUX);
163 }
164 
165 #define COMPOSE_AUX_SW_DATA_16_20(command, address) \
166 	((command) | ((0xF0000 & (address)) >> 16))
167 
168 #define COMPOSE_AUX_SW_DATA_8_15(address) \
169 	((0xFF00 & (address)) >> 8)
170 
171 #define COMPOSE_AUX_SW_DATA_0_7(address) \
172 	(0xFF & (address))
173 
174 static void submit_channel_request(
175 	struct dce_aux *engine,
176 	struct aux_request_transaction_data *request)
177 {
178 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(engine);
179 	uint32_t value;
180 	uint32_t length;
181 
182 	bool is_write =
183 		((request->type == AUX_TRANSACTION_TYPE_DP) &&
184 		 (request->action == I2CAUX_TRANSACTION_ACTION_DP_WRITE)) ||
185 		((request->type == AUX_TRANSACTION_TYPE_I2C) &&
186 		((request->action == I2CAUX_TRANSACTION_ACTION_I2C_WRITE) ||
187 		 (request->action == I2CAUX_TRANSACTION_ACTION_I2C_WRITE_MOT)));
188 	if (REG(AUXN_IMPCAL)) {
189 		/* clear_aux_error */
190 		REG_UPDATE_SEQ_2(AUXN_IMPCAL,
191 				AUXN_CALOUT_ERROR_AK, 1,
192 				AUXN_CALOUT_ERROR_AK, 0);
193 
194 		REG_UPDATE_SEQ_2(AUXP_IMPCAL,
195 				AUXP_CALOUT_ERROR_AK, 1,
196 				AUXP_CALOUT_ERROR_AK, 0);
197 
198 		/* force_default_calibrate */
199 		REG_UPDATE_SEQ_2(AUXN_IMPCAL,
200 				AUXN_IMPCAL_ENABLE, 1,
201 				AUXN_IMPCAL_OVERRIDE_ENABLE, 0);
202 
203 		/* bug? why AUXN update EN and OVERRIDE_EN 1 by 1 while AUX P toggles OVERRIDE? */
204 
205 		REG_UPDATE_SEQ_2(AUXP_IMPCAL,
206 				AUXP_IMPCAL_OVERRIDE_ENABLE, 1,
207 				AUXP_IMPCAL_OVERRIDE_ENABLE, 0);
208 	}
209 
210 	REG_UPDATE(AUX_INTERRUPT_CONTROL, AUX_SW_DONE_ACK, 1);
211 
212 	REG_WAIT(AUX_SW_STATUS, AUX_SW_DONE, 0,
213 				10, aux110->polling_timeout_period/10);
214 
215 	/* set the delay and the number of bytes to write */
216 
217 	/* The length include
218 	 * the 4 bit header and the 20 bit address
219 	 * (that is 3 byte).
220 	 * If the requested length is non zero this means
221 	 * an addition byte specifying the length is required.
222 	 */
223 
224 	length = request->length ? 4 : 3;
225 	if (is_write)
226 		length += request->length;
227 
228 	REG_UPDATE_2(AUX_SW_CONTROL,
229 			AUX_SW_START_DELAY, request->delay,
230 			AUX_SW_WR_BYTES, length);
231 
232 	/* program action and address and payload data (if 'is_write') */
233 	value = REG_UPDATE_4(AUX_SW_DATA,
234 			AUX_SW_INDEX, 0,
235 			AUX_SW_DATA_RW, 0,
236 			AUX_SW_AUTOINCREMENT_DISABLE, 1,
237 			AUX_SW_DATA, COMPOSE_AUX_SW_DATA_16_20(request->action, request->address));
238 
239 	value = REG_SET_2(AUX_SW_DATA, value,
240 			AUX_SW_AUTOINCREMENT_DISABLE, 0,
241 			AUX_SW_DATA, COMPOSE_AUX_SW_DATA_8_15(request->address));
242 
243 	value = REG_SET(AUX_SW_DATA, value,
244 			AUX_SW_DATA, COMPOSE_AUX_SW_DATA_0_7(request->address));
245 
246 	if (request->length) {
247 		value = REG_SET(AUX_SW_DATA, value,
248 				AUX_SW_DATA, request->length - 1);
249 	}
250 
251 	if (is_write) {
252 		/* Load the HW buffer with the Data to be sent.
253 		 * This is relevant for write operation.
254 		 * For read, the data recived data will be
255 		 * processed in process_channel_reply().
256 		 */
257 		uint32_t i = 0;
258 
259 		while (i < request->length) {
260 			value = REG_SET(AUX_SW_DATA, value,
261 					AUX_SW_DATA, request->data[i]);
262 
263 			++i;
264 		}
265 	}
266 
267 	REG_UPDATE(AUX_SW_CONTROL, AUX_SW_GO, 1);
268 	EVENT_LOG_AUX_REQ(engine->ddc->pin_data->en, EVENT_LOG_AUX_ORIGIN_NATIVE,
269 					request->action, request->address, request->length, request->data);
270 }
271 
272 static int read_channel_reply(struct dce_aux *engine, uint32_t size,
273 			      uint8_t *buffer, uint8_t *reply_result,
274 			      uint32_t *sw_status)
275 {
276 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(engine);
277 	uint32_t bytes_replied;
278 	uint32_t reply_result_32;
279 
280 	*sw_status = REG_GET(AUX_SW_STATUS, AUX_SW_REPLY_BYTE_COUNT,
281 			     &bytes_replied);
282 
283 	/* In case HPD is LOW, exit AUX transaction */
284 	if ((*sw_status & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK))
285 		return -1;
286 
287 	/* Need at least the status byte */
288 	if (!bytes_replied)
289 		return -1;
290 
291 	REG_UPDATE_SEQ_3(AUX_SW_DATA,
292 			  AUX_SW_INDEX, 0,
293 			  AUX_SW_AUTOINCREMENT_DISABLE, 1,
294 			  AUX_SW_DATA_RW, 1);
295 
296 	REG_GET(AUX_SW_DATA, AUX_SW_DATA, &reply_result_32);
297 	reply_result_32 = reply_result_32 >> 4;
298 	if (reply_result != NULL)
299 		*reply_result = (uint8_t)reply_result_32;
300 
301 	if (reply_result_32 == 0) { /* ACK */
302 		uint32_t i = 0;
303 
304 		/* First byte was already used to get the command status */
305 		--bytes_replied;
306 
307 		/* Do not overflow buffer */
308 		if (bytes_replied > size)
309 			return -1;
310 
311 		while (i < bytes_replied) {
312 			uint32_t aux_sw_data_val;
313 
314 			REG_GET(AUX_SW_DATA, AUX_SW_DATA, &aux_sw_data_val);
315 			buffer[i] = aux_sw_data_val;
316 			++i;
317 		}
318 
319 		return i;
320 	}
321 
322 	return 0;
323 }
324 
325 static enum aux_channel_operation_result get_channel_status(
326 	struct dce_aux *engine,
327 	uint8_t *returned_bytes)
328 {
329 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(engine);
330 
331 	uint32_t value;
332 
333 	if (returned_bytes == NULL) {
334 		/*caller pass NULL pointer*/
335 		ASSERT_CRITICAL(false);
336 		return AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN;
337 	}
338 	*returned_bytes = 0;
339 
340 	/* poll to make sure that SW_DONE is asserted */
341 	REG_WAIT(AUX_SW_STATUS, AUX_SW_DONE, 1,
342 				10, aux110->polling_timeout_period/10);
343 
344 	value = REG_READ(AUX_SW_STATUS);
345 	/* in case HPD is LOW, exit AUX transaction */
346 	if ((value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK))
347 		return AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON;
348 
349 	/* Note that the following bits are set in 'status.bits'
350 	 * during CTS 4.2.1.2 (FW 3.3.1):
351 	 * AUX_SW_RX_MIN_COUNT_VIOL, AUX_SW_RX_INVALID_STOP,
352 	 * AUX_SW_RX_RECV_NO_DET, AUX_SW_RX_RECV_INVALID_H.
353 	 *
354 	 * AUX_SW_RX_MIN_COUNT_VIOL is an internal,
355 	 * HW debugging bit and should be ignored.
356 	 */
357 	if (value & AUX_SW_STATUS__AUX_SW_DONE_MASK) {
358 		if ((value & AUX_SW_STATUS__AUX_SW_RX_TIMEOUT_STATE_MASK) ||
359 			(value & AUX_SW_STATUS__AUX_SW_RX_TIMEOUT_MASK))
360 			return AUX_CHANNEL_OPERATION_FAILED_TIMEOUT;
361 
362 		else if ((value & AUX_SW_STATUS__AUX_SW_RX_INVALID_STOP_MASK) ||
363 			(value & AUX_SW_STATUS__AUX_SW_RX_RECV_NO_DET_MASK) ||
364 			(value &
365 				AUX_SW_STATUS__AUX_SW_RX_RECV_INVALID_H_MASK) ||
366 			(value & AUX_SW_STATUS__AUX_SW_RX_RECV_INVALID_L_MASK))
367 			return AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY;
368 
369 		*returned_bytes = get_reg_field_value(value,
370 				AUX_SW_STATUS,
371 				AUX_SW_REPLY_BYTE_COUNT);
372 
373 		if (*returned_bytes == 0)
374 			return
375 			AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY;
376 		else {
377 			*returned_bytes -= 1;
378 			return AUX_CHANNEL_OPERATION_SUCCEEDED;
379 		}
380 	} else {
381 		/*time_elapsed >= aux_engine->timeout_period
382 		 *  AUX_SW_STATUS__AUX_SW_HPD_DISCON = at this point
383 		 */
384 		ASSERT_CRITICAL(false);
385 		return AUX_CHANNEL_OPERATION_FAILED_TIMEOUT;
386 	}
387 }
388 
389 enum i2caux_engine_type get_engine_type(
390 		const struct dce_aux *engine)
391 {
392 	return I2CAUX_ENGINE_TYPE_AUX;
393 }
394 
395 static bool acquire(
396 	struct dce_aux *engine,
397 	struct ddc *ddc)
398 {
399 	enum gpio_result result;
400 
401 	if (!is_engine_available(engine))
402 		return false;
403 
404 	result = dal_ddc_open(ddc, GPIO_MODE_HARDWARE,
405 		GPIO_DDC_CONFIG_TYPE_MODE_AUX);
406 
407 	if (result != GPIO_RESULT_OK)
408 		return false;
409 
410 	if (!acquire_engine(engine)) {
411 		dal_ddc_close(ddc);
412 		return false;
413 	}
414 
415 	engine->ddc = ddc;
416 
417 	return true;
418 }
419 
420 void dce110_engine_destroy(struct dce_aux **engine)
421 {
422 
423 	struct aux_engine_dce110 *engine110 = FROM_AUX_ENGINE(*engine);
424 
425 	kfree(engine110);
426 	*engine = NULL;
427 
428 }
429 
430 static bool dce_aux_configure_timeout(struct ddc_service *ddc,
431 		uint32_t timeout_in_us)
432 {
433 	uint32_t multiplier = 0;
434 	uint32_t length = 0;
435 	struct ddc *ddc_pin = ddc->ddc_pin;
436 	struct dce_aux *aux_engine = ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en];
437 	struct aux_engine_dce110 *aux110 = FROM_AUX_ENGINE(aux_engine);
438 
439 	/* 1-Update polling timeout period */
440 	aux110->polling_timeout_period = timeout_in_us * SW_AUX_TIMEOUT_PERIOD_MULTIPLIER;
441 
442 	/* 2-Update aux timeout period length and multiplier */
443 	if (timeout_in_us <= TIME_OUT_INCREMENT) {
444 		multiplier = 0;
445 		length = timeout_in_us/TIME_OUT_MULTIPLIER_8;
446 		if (timeout_in_us % TIME_OUT_MULTIPLIER_8 != 0)
447 			length++;
448 	} else if (timeout_in_us <= 2 * TIME_OUT_INCREMENT) {
449 		multiplier = 1;
450 		length = timeout_in_us/TIME_OUT_MULTIPLIER_16;
451 		if (timeout_in_us % TIME_OUT_MULTIPLIER_16 != 0)
452 			length++;
453 	} else if (timeout_in_us <= 4 * TIME_OUT_INCREMENT) {
454 		multiplier = 2;
455 		length = timeout_in_us/TIME_OUT_MULTIPLIER_32;
456 		if (timeout_in_us % TIME_OUT_MULTIPLIER_32 != 0)
457 			length++;
458 	} else if (timeout_in_us > 4 * TIME_OUT_INCREMENT) {
459 		multiplier = 3;
460 		length = timeout_in_us/TIME_OUT_MULTIPLIER_64;
461 		if (timeout_in_us % TIME_OUT_MULTIPLIER_64 != 0)
462 			length++;
463 	}
464 
465 	length = (length < MAX_TIMEOUT_LENGTH) ? length : MAX_TIMEOUT_LENGTH;
466 
467 	REG_UPDATE_SEQ_2(AUX_DPHY_RX_CONTROL1, AUX_RX_TIMEOUT_LEN, length, AUX_RX_TIMEOUT_LEN_MUL, multiplier);
468 
469 	return true;
470 }
471 
472 static struct dce_aux_funcs aux_functions = {
473 	.configure_timeout = NULL,
474 	.destroy = NULL,
475 };
476 
477 struct dce_aux *dce110_aux_engine_construct(struct aux_engine_dce110 *aux_engine110,
478 		struct dc_context *ctx,
479 		uint32_t inst,
480 		uint32_t timeout_period,
481 		const struct dce110_aux_registers *regs,
482 		const struct dce110_aux_registers_mask *mask,
483 		const struct dce110_aux_registers_shift *shift,
484 		bool is_ext_aux_timeout_configurable)
485 {
486 	aux_engine110->base.ddc = NULL;
487 	aux_engine110->base.ctx = ctx;
488 	aux_engine110->base.delay = 0;
489 	aux_engine110->base.max_defer_write_retry = 0;
490 	aux_engine110->base.inst = inst;
491 	aux_engine110->polling_timeout_period = timeout_period;
492 	aux_engine110->regs = regs;
493 
494 	aux_engine110->mask = mask;
495 	aux_engine110->shift = shift;
496 	aux_engine110->base.funcs = &aux_functions;
497 	if (is_ext_aux_timeout_configurable)
498 		aux_engine110->base.funcs->configure_timeout = &dce_aux_configure_timeout;
499 
500 	return &aux_engine110->base;
501 }
502 
503 static enum i2caux_transaction_action i2caux_action_from_payload(struct aux_payload *payload)
504 {
505 	if (payload->i2c_over_aux) {
506 		if (payload->write) {
507 			if (payload->mot)
508 				return I2CAUX_TRANSACTION_ACTION_I2C_WRITE_MOT;
509 			return I2CAUX_TRANSACTION_ACTION_I2C_WRITE;
510 		}
511 		if (payload->mot)
512 			return I2CAUX_TRANSACTION_ACTION_I2C_READ_MOT;
513 		return I2CAUX_TRANSACTION_ACTION_I2C_READ;
514 	}
515 	if (payload->write)
516 		return I2CAUX_TRANSACTION_ACTION_DP_WRITE;
517 	return I2CAUX_TRANSACTION_ACTION_DP_READ;
518 }
519 
520 int dce_aux_transfer_raw(struct ddc_service *ddc,
521 		struct aux_payload *payload,
522 		enum aux_channel_operation_result *operation_result)
523 {
524 	struct ddc *ddc_pin = ddc->ddc_pin;
525 	struct dce_aux *aux_engine;
526 	struct aux_request_transaction_data aux_req;
527 	struct aux_reply_transaction_data aux_rep;
528 	uint8_t returned_bytes = 0;
529 	int res = -1;
530 	uint32_t status;
531 
532 	memset(&aux_req, 0, sizeof(aux_req));
533 	memset(&aux_rep, 0, sizeof(aux_rep));
534 
535 	aux_engine = ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en];
536 	if (!acquire(aux_engine, ddc_pin)) {
537 		*operation_result = AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE;
538 		return -1;
539 	}
540 
541 	if (payload->i2c_over_aux)
542 		aux_req.type = AUX_TRANSACTION_TYPE_I2C;
543 	else
544 		aux_req.type = AUX_TRANSACTION_TYPE_DP;
545 
546 	aux_req.action = i2caux_action_from_payload(payload);
547 
548 	aux_req.address = payload->address;
549 	aux_req.delay = 0;
550 	aux_req.length = payload->length;
551 	aux_req.data = payload->data;
552 
553 	submit_channel_request(aux_engine, &aux_req);
554 	*operation_result = get_channel_status(aux_engine, &returned_bytes);
555 
556 	if (*operation_result == AUX_CHANNEL_OPERATION_SUCCEEDED) {
557 		int bytes_replied = 0;
558 		bytes_replied = read_channel_reply(aux_engine, payload->length,
559 					 payload->data, payload->reply,
560 					 &status);
561 		EVENT_LOG_AUX_REP(aux_engine->ddc->pin_data->en,
562 					EVENT_LOG_AUX_ORIGIN_NATIVE, *payload->reply,
563 					bytes_replied, payload->data);
564 		res = returned_bytes;
565 	} else {
566 		res = -1;
567 	}
568 
569 	release_engine(aux_engine);
570 	return res;
571 }
572 
573 #define AUX_MAX_RETRIES 7
574 #define AUX_MAX_DEFER_RETRIES 7
575 #define AUX_MAX_I2C_DEFER_RETRIES 7
576 #define AUX_MAX_INVALID_REPLY_RETRIES 2
577 #define AUX_MAX_TIMEOUT_RETRIES 3
578 
579 bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
580 		struct aux_payload *payload)
581 {
582 	int i, ret = 0;
583 	uint8_t reply;
584 	bool payload_reply = true;
585 	enum aux_channel_operation_result operation_result;
586 	bool retry_on_defer = false;
587 
588 	int aux_ack_retries = 0,
589 		aux_defer_retries = 0,
590 		aux_i2c_defer_retries = 0,
591 		aux_timeout_retries = 0,
592 		aux_invalid_reply_retries = 0;
593 
594 	if (!payload->reply) {
595 		payload_reply = false;
596 		payload->reply = &reply;
597 	}
598 
599 	for (i = 0; i < AUX_MAX_RETRIES; i++) {
600 		ret = dce_aux_transfer_raw(ddc, payload, &operation_result);
601 		switch (operation_result) {
602 		case AUX_CHANNEL_OPERATION_SUCCEEDED:
603 			aux_timeout_retries = 0;
604 			aux_invalid_reply_retries = 0;
605 
606 			switch (*payload->reply) {
607 			case AUX_TRANSACTION_REPLY_AUX_ACK:
608 				if (!payload->write && payload->length != ret) {
609 					if (++aux_ack_retries >= AUX_MAX_RETRIES)
610 						goto fail;
611 					else
612 						udelay(300);
613 				} else
614 					return true;
615 			break;
616 
617 			case AUX_TRANSACTION_REPLY_AUX_DEFER:
618 			case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER:
619 				retry_on_defer = true;
620 				/* fall through */
621 			case AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK:
622 				if (++aux_defer_retries >= AUX_MAX_DEFER_RETRIES) {
623 					goto fail;
624 				} else {
625 					if ((*payload->reply == AUX_TRANSACTION_REPLY_AUX_DEFER) ||
626 						(*payload->reply == AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER)) {
627 						if (payload->defer_delay > 0)
628 							msleep(payload->defer_delay);
629 					}
630 				}
631 				break;
632 
633 			case AUX_TRANSACTION_REPLY_I2C_DEFER:
634 				aux_defer_retries = 0;
635 				if (++aux_i2c_defer_retries >= AUX_MAX_I2C_DEFER_RETRIES)
636 					goto fail;
637 				break;
638 
639 			case AUX_TRANSACTION_REPLY_AUX_NACK:
640 			case AUX_TRANSACTION_REPLY_HPD_DISCON:
641 			default:
642 				goto fail;
643 			}
644 			break;
645 
646 		case AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY:
647 			if (++aux_invalid_reply_retries >= AUX_MAX_INVALID_REPLY_RETRIES)
648 				goto fail;
649 			else
650 				udelay(400);
651 			break;
652 
653 		case AUX_CHANNEL_OPERATION_FAILED_TIMEOUT:
654 			// Check whether a DEFER had occurred before the timeout.
655 			// If so, treat timeout as a DEFER.
656 			if (retry_on_defer) {
657 				if (++aux_defer_retries >= AUX_MAX_DEFER_RETRIES)
658 					goto fail;
659 				else if (payload->defer_delay > 0)
660 					msleep(payload->defer_delay);
661 			} else {
662 				if (++aux_timeout_retries >= AUX_MAX_TIMEOUT_RETRIES)
663 					goto fail;
664 				else {
665 					/*
666 					 * DP 1.4, 2.8.2:  AUX Transaction Response/Reply Timeouts
667 					 * According to the DP spec there should be 3 retries total
668 					 * with a 400us wait inbetween each. Hardware already waits
669 					 * for 550us therefore no wait is required here.
670 					 */
671 				}
672 			}
673 			break;
674 
675 		case AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON:
676 		case AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE:
677 		case AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN:
678 		default:
679 			goto fail;
680 		}
681 	}
682 
683 fail:
684 	if (!payload_reply)
685 		payload->reply = NULL;
686 	return false;
687 }
688