1 /*
2  * Copyright (c) 2006-2008 Intel Corporation
3  * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
4  *
5  * DRM core CRTC related functions
6  *
7  * Permission to use, copy, modify, distribute, and sell this software and its
8  * documentation for any purpose is hereby granted without fee, provided that
9  * the above copyright notice appear in all copies and that both that copyright
10  * notice and this permission notice appear in supporting documentation, and
11  * that the name of the copyright holders not be used in advertising or
12  * publicity pertaining to distribution of the software without specific,
13  * written prior permission.  The copyright holders make no representations
14  * about the suitability of this software for any purpose.  It is provided "as
15  * is" without express or implied warranty.
16  *
17  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
18  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
19  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
20  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
21  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
22  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
23  * OF THIS SOFTWARE.
24  *
25  * Authors:
26  *      Keith Packard
27  *	Eric Anholt <eric@anholt.net>
28  *      Dave Airlie <airlied@linux.ie>
29  *      Jesse Barnes <jesse.barnes@intel.com>
30  */
31 
32 #include <linux/export.h>
33 #include <linux/moduleparam.h>
34 
35 #include <drm/drm_bridge.h>
36 #include <drm/drm_client.h>
37 #include <drm/drm_crtc.h>
38 #include <drm/drm_edid.h>
39 #include <drm/drm_fb_helper.h>
40 #include <drm/drm_fourcc.h>
41 #include <drm/drm_modeset_helper_vtables.h>
42 #include <drm/drm_print.h>
43 #include <drm/drm_probe_helper.h>
44 #include <drm/drm_sysfs.h>
45 
46 #include "drm_crtc_helper_internal.h"
47 
48 /**
49  * DOC: output probing helper overview
50  *
51  * This library provides some helper code for output probing. It provides an
52  * implementation of the core &drm_connector_funcs.fill_modes interface with
53  * drm_helper_probe_single_connector_modes().
54  *
55  * It also provides support for polling connectors with a work item and for
56  * generic hotplug interrupt handling where the driver doesn't or cannot keep
57  * track of a per-connector hpd interrupt.
58  *
59  * This helper library can be used independently of the modeset helper library.
60  * Drivers can also overwrite different parts e.g. use their own hotplug
61  * handling code to avoid probing unrelated outputs.
62  *
63  * The probe helpers share the function table structures with other display
64  * helper libraries. See &struct drm_connector_helper_funcs for the details.
65  */
66 
67 static bool drm_kms_helper_poll = true;
68 module_param_named(poll, drm_kms_helper_poll, bool, 0600);
69 
70 static enum drm_mode_status
71 drm_mode_validate_flag(const struct drm_display_mode *mode,
72 		       int flags)
73 {
74 	if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
75 	    !(flags & DRM_MODE_FLAG_INTERLACE))
76 		return MODE_NO_INTERLACE;
77 
78 	if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
79 	    !(flags & DRM_MODE_FLAG_DBLSCAN))
80 		return MODE_NO_DBLESCAN;
81 
82 	if ((mode->flags & DRM_MODE_FLAG_3D_MASK) &&
83 	    !(flags & DRM_MODE_FLAG_3D_MASK))
84 		return MODE_NO_STEREO;
85 
86 	return MODE_OK;
87 }
88 
89 static int
90 drm_mode_validate_pipeline(struct drm_display_mode *mode,
91 			   struct drm_connector *connector,
92 			   struct drm_modeset_acquire_ctx *ctx,
93 			   enum drm_mode_status *status)
94 {
95 	struct drm_device *dev = connector->dev;
96 	struct drm_encoder *encoder;
97 	int ret;
98 
99 	/* Step 1: Validate against connector */
100 	ret = drm_connector_mode_valid(connector, mode, ctx, status);
101 	if (ret || *status != MODE_OK)
102 		return ret;
103 
104 	/* Step 2: Validate against encoders and crtcs */
105 	drm_connector_for_each_possible_encoder(connector, encoder) {
106 		struct drm_bridge *bridge;
107 		struct drm_crtc *crtc;
108 
109 		*status = drm_encoder_mode_valid(encoder, mode);
110 		if (*status != MODE_OK) {
111 			/* No point in continuing for crtc check as this encoder
112 			 * will not accept the mode anyway. If all encoders
113 			 * reject the mode then, at exit, ret will not be
114 			 * MODE_OK. */
115 			continue;
116 		}
117 
118 		bridge = drm_bridge_chain_get_first_bridge(encoder);
119 		*status = drm_bridge_chain_mode_valid(bridge,
120 						      &connector->display_info,
121 						      mode);
122 		if (*status != MODE_OK) {
123 			/* There is also no point in continuing for crtc check
124 			 * here. */
125 			continue;
126 		}
127 
128 		drm_for_each_crtc(crtc, dev) {
129 			if (!drm_encoder_crtc_ok(encoder, crtc))
130 				continue;
131 
132 			*status = drm_crtc_mode_valid(crtc, mode);
133 			if (*status == MODE_OK) {
134 				/* If we get to this point there is at least
135 				 * one combination of encoder+crtc that works
136 				 * for this mode. Lets return now. */
137 				return 0;
138 			}
139 		}
140 	}
141 
142 	return 0;
143 }
144 
145 static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
146 {
147 	struct drm_cmdline_mode *cmdline_mode;
148 	struct drm_display_mode *mode;
149 
150 	cmdline_mode = &connector->cmdline_mode;
151 	if (!cmdline_mode->specified)
152 		return 0;
153 
154 	/* Only add a GTF mode if we find no matching probed modes */
155 	list_for_each_entry(mode, &connector->probed_modes, head) {
156 		if (mode->hdisplay != cmdline_mode->xres ||
157 		    mode->vdisplay != cmdline_mode->yres)
158 			continue;
159 
160 		if (cmdline_mode->refresh_specified) {
161 			/* The probed mode's vrefresh is set until later */
162 			if (drm_mode_vrefresh(mode) != cmdline_mode->refresh)
163 				continue;
164 		}
165 
166 		/* Mark the matching mode as being preferred by the user */
167 		mode->type |= DRM_MODE_TYPE_USERDEF;
168 		return 0;
169 	}
170 
171 	mode = drm_mode_create_from_cmdline_mode(connector->dev,
172 						 cmdline_mode);
173 	if (mode == NULL)
174 		return 0;
175 
176 	drm_mode_probed_add(connector, mode);
177 	return 1;
178 }
179 
180 enum drm_mode_status drm_crtc_mode_valid(struct drm_crtc *crtc,
181 					 const struct drm_display_mode *mode)
182 {
183 	const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
184 
185 	if (!crtc_funcs || !crtc_funcs->mode_valid)
186 		return MODE_OK;
187 
188 	return crtc_funcs->mode_valid(crtc, mode);
189 }
190 
191 enum drm_mode_status drm_encoder_mode_valid(struct drm_encoder *encoder,
192 					    const struct drm_display_mode *mode)
193 {
194 	const struct drm_encoder_helper_funcs *encoder_funcs =
195 		encoder->helper_private;
196 
197 	if (!encoder_funcs || !encoder_funcs->mode_valid)
198 		return MODE_OK;
199 
200 	return encoder_funcs->mode_valid(encoder, mode);
201 }
202 
203 int
204 drm_connector_mode_valid(struct drm_connector *connector,
205 			 struct drm_display_mode *mode,
206 			 struct drm_modeset_acquire_ctx *ctx,
207 			 enum drm_mode_status *status)
208 {
209 	const struct drm_connector_helper_funcs *connector_funcs =
210 		connector->helper_private;
211 	int ret = 0;
212 
213 	if (!connector_funcs)
214 		*status = MODE_OK;
215 	else if (connector_funcs->mode_valid_ctx)
216 		ret = connector_funcs->mode_valid_ctx(connector, mode, ctx,
217 						      status);
218 	else if (connector_funcs->mode_valid)
219 		*status = connector_funcs->mode_valid(connector, mode);
220 	else
221 		*status = MODE_OK;
222 
223 	return ret;
224 }
225 
226 #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
227 /**
228  * drm_kms_helper_poll_enable - re-enable output polling.
229  * @dev: drm_device
230  *
231  * This function re-enables the output polling work, after it has been
232  * temporarily disabled using drm_kms_helper_poll_disable(), for example over
233  * suspend/resume.
234  *
235  * Drivers can call this helper from their device resume implementation. It is
236  * not an error to call this even when output polling isn't enabled.
237  *
238  * Note that calls to enable and disable polling must be strictly ordered, which
239  * is automatically the case when they're only call from suspend/resume
240  * callbacks.
241  */
242 void drm_kms_helper_poll_enable(struct drm_device *dev)
243 {
244 	bool poll = false;
245 	struct drm_connector *connector;
246 	struct drm_connector_list_iter conn_iter;
247 	unsigned long delay = DRM_OUTPUT_POLL_PERIOD;
248 
249 	if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
250 		return;
251 
252 	drm_connector_list_iter_begin(dev, &conn_iter);
253 	drm_for_each_connector_iter(connector, &conn_iter) {
254 		if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
255 					 DRM_CONNECTOR_POLL_DISCONNECT))
256 			poll = true;
257 	}
258 	drm_connector_list_iter_end(&conn_iter);
259 
260 	if (dev->mode_config.delayed_event) {
261 		/*
262 		 * FIXME:
263 		 *
264 		 * Use short (1s) delay to handle the initial delayed event.
265 		 * This delay should not be needed, but Optimus/nouveau will
266 		 * fail in a mysterious way if the delayed event is handled as
267 		 * soon as possible like it is done in
268 		 * drm_helper_probe_single_connector_modes() in case the poll
269 		 * was enabled before.
270 		 */
271 		poll = true;
272 		delay = HZ;
273 	}
274 
275 	if (poll)
276 		schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
277 }
278 EXPORT_SYMBOL(drm_kms_helper_poll_enable);
279 
280 static enum drm_connector_status
281 drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
282 {
283 	const struct drm_connector_helper_funcs *funcs = connector->helper_private;
284 	struct drm_modeset_acquire_ctx ctx;
285 	int ret;
286 
287 	drm_modeset_acquire_init(&ctx, 0);
288 
289 retry:
290 	ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex, &ctx);
291 	if (!ret) {
292 		if (funcs->detect_ctx)
293 			ret = funcs->detect_ctx(connector, &ctx, force);
294 		else if (connector->funcs->detect)
295 			ret = connector->funcs->detect(connector, force);
296 		else
297 			ret = connector_status_connected;
298 	}
299 
300 	if (ret == -EDEADLK) {
301 		drm_modeset_backoff(&ctx);
302 		goto retry;
303 	}
304 
305 	if (WARN_ON(ret < 0))
306 		ret = connector_status_unknown;
307 
308 	if (ret != connector->status)
309 		connector->epoch_counter += 1;
310 
311 	drm_modeset_drop_locks(&ctx);
312 	drm_modeset_acquire_fini(&ctx);
313 
314 	return ret;
315 }
316 
317 /**
318  * drm_helper_probe_detect - probe connector status
319  * @connector: connector to probe
320  * @ctx: acquire_ctx, or NULL to let this function handle locking.
321  * @force: Whether destructive probe operations should be performed.
322  *
323  * This function calls the detect callbacks of the connector.
324  * This function returns &drm_connector_status, or
325  * if @ctx is set, it might also return -EDEADLK.
326  */
327 int
328 drm_helper_probe_detect(struct drm_connector *connector,
329 			struct drm_modeset_acquire_ctx *ctx,
330 			bool force)
331 {
332 	const struct drm_connector_helper_funcs *funcs = connector->helper_private;
333 	struct drm_device *dev = connector->dev;
334 	int ret;
335 
336 	if (!ctx)
337 		return drm_helper_probe_detect_ctx(connector, force);
338 
339 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
340 	if (ret)
341 		return ret;
342 
343 	if (funcs->detect_ctx)
344 		ret = funcs->detect_ctx(connector, ctx, force);
345 	else if (connector->funcs->detect)
346 		ret = connector->funcs->detect(connector, force);
347 	else
348 		ret = connector_status_connected;
349 
350 	if (ret != connector->status)
351 		connector->epoch_counter += 1;
352 
353 	return ret;
354 }
355 EXPORT_SYMBOL(drm_helper_probe_detect);
356 
357 static int drm_helper_probe_get_modes(struct drm_connector *connector)
358 {
359 	const struct drm_connector_helper_funcs *connector_funcs =
360 		connector->helper_private;
361 	int count;
362 
363 	count = connector_funcs->get_modes(connector);
364 
365 	/*
366 	 * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
367 	 * override/firmware EDID.
368 	 */
369 	if (count == 0 && connector->status == connector_status_connected)
370 		count = drm_add_override_edid_modes(connector);
371 
372 	return count;
373 }
374 
375 static int __drm_helper_update_and_validate(struct drm_connector *connector,
376 					    uint32_t maxX, uint32_t maxY,
377 					    struct drm_modeset_acquire_ctx *ctx)
378 {
379 	struct drm_device *dev = connector->dev;
380 	struct drm_display_mode *mode;
381 	int mode_flags = 0;
382 	int ret;
383 
384 	drm_connector_list_update(connector);
385 
386 	if (connector->interlace_allowed)
387 		mode_flags |= DRM_MODE_FLAG_INTERLACE;
388 	if (connector->doublescan_allowed)
389 		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
390 	if (connector->stereo_allowed)
391 		mode_flags |= DRM_MODE_FLAG_3D_MASK;
392 
393 	list_for_each_entry(mode, &connector->modes, head) {
394 		if (mode->status != MODE_OK)
395 			continue;
396 
397 		mode->status = drm_mode_validate_driver(dev, mode);
398 		if (mode->status != MODE_OK)
399 			continue;
400 
401 		mode->status = drm_mode_validate_size(mode, maxX, maxY);
402 		if (mode->status != MODE_OK)
403 			continue;
404 
405 		mode->status = drm_mode_validate_flag(mode, mode_flags);
406 		if (mode->status != MODE_OK)
407 			continue;
408 
409 		ret = drm_mode_validate_pipeline(mode, connector, ctx,
410 						 &mode->status);
411 		if (ret) {
412 			drm_dbg_kms(dev,
413 				    "drm_mode_validate_pipeline failed: %d\n",
414 				    ret);
415 
416 			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
417 				mode->status = MODE_ERROR;
418 			else
419 				return -EDEADLK;
420 		}
421 
422 		if (mode->status != MODE_OK)
423 			continue;
424 		mode->status = drm_mode_validate_ycbcr420(mode, connector);
425 	}
426 
427 	return 0;
428 }
429 
430 /**
431  * drm_helper_probe_single_connector_modes - get complete set of display modes
432  * @connector: connector to probe
433  * @maxX: max width for modes
434  * @maxY: max height for modes
435  *
436  * Based on the helper callbacks implemented by @connector in struct
437  * &drm_connector_helper_funcs try to detect all valid modes.  Modes will first
438  * be added to the connector's probed_modes list, then culled (based on validity
439  * and the @maxX, @maxY parameters) and put into the normal modes list.
440  *
441  * Intended to be used as a generic implementation of the
442  * &drm_connector_funcs.fill_modes() vfunc for drivers that use the CRTC helpers
443  * for output mode filtering and detection.
444  *
445  * The basic procedure is as follows
446  *
447  * 1. All modes currently on the connector's modes list are marked as stale
448  *
449  * 2. New modes are added to the connector's probed_modes list with
450  *    drm_mode_probed_add(). New modes start their life with status as OK.
451  *    Modes are added from a single source using the following priority order.
452  *
453  *    - &drm_connector_helper_funcs.get_modes vfunc
454  *    - if the connector status is connector_status_connected, standard
455  *      VESA DMT modes up to 1024x768 are automatically added
456  *      (drm_add_modes_noedid())
457  *
458  *    Finally modes specified via the kernel command line (video=...) are
459  *    added in addition to what the earlier probes produced
460  *    (drm_helper_probe_add_cmdline_mode()). These modes are generated
461  *    using the VESA GTF/CVT formulas.
462  *
463  * 3. Modes are moved from the probed_modes list to the modes list. Potential
464  *    duplicates are merged together (see drm_connector_list_update()).
465  *    After this step the probed_modes list will be empty again.
466  *
467  * 4. Any non-stale mode on the modes list then undergoes validation
468  *
469  *    - drm_mode_validate_basic() performs basic sanity checks
470  *    - drm_mode_validate_size() filters out modes larger than @maxX and @maxY
471  *      (if specified)
472  *    - drm_mode_validate_flag() checks the modes against basic connector
473  *      capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
474  *    - the optional &drm_connector_helper_funcs.mode_valid or
475  *      &drm_connector_helper_funcs.mode_valid_ctx helpers can perform driver
476  *      and/or sink specific checks
477  *    - the optional &drm_crtc_helper_funcs.mode_valid,
478  *      &drm_bridge_funcs.mode_valid and &drm_encoder_helper_funcs.mode_valid
479  *      helpers can perform driver and/or source specific checks which are also
480  *      enforced by the modeset/atomic helpers
481  *
482  * 5. Any mode whose status is not OK is pruned from the connector's modes list,
483  *    accompanied by a debug message indicating the reason for the mode's
484  *    rejection (see drm_mode_prune_invalid()).
485  *
486  * Returns:
487  * The number of modes found on @connector.
488  */
489 int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
490 					    uint32_t maxX, uint32_t maxY)
491 {
492 	struct drm_device *dev = connector->dev;
493 	struct drm_display_mode *mode;
494 	int count = 0, ret;
495 	enum drm_connector_status old_status;
496 	struct drm_modeset_acquire_ctx ctx;
497 
498 	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
499 
500 	drm_modeset_acquire_init(&ctx, 0);
501 
502 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
503 			connector->name);
504 
505 retry:
506 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
507 	if (ret == -EDEADLK) {
508 		drm_modeset_backoff(&ctx);
509 		goto retry;
510 	} else
511 		WARN_ON(ret < 0);
512 
513 	/* set all old modes to the stale state */
514 	list_for_each_entry(mode, &connector->modes, head)
515 		mode->status = MODE_STALE;
516 
517 	old_status = connector->status;
518 
519 	if (connector->force) {
520 		if (connector->force == DRM_FORCE_ON ||
521 		    connector->force == DRM_FORCE_ON_DIGITAL)
522 			connector->status = connector_status_connected;
523 		else
524 			connector->status = connector_status_disconnected;
525 		if (connector->funcs->force)
526 			connector->funcs->force(connector);
527 	} else {
528 		ret = drm_helper_probe_detect(connector, &ctx, true);
529 
530 		if (ret == -EDEADLK) {
531 			drm_modeset_backoff(&ctx);
532 			goto retry;
533 		} else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
534 			ret = connector_status_unknown;
535 
536 		connector->status = ret;
537 	}
538 
539 	/*
540 	 * Normally either the driver's hpd code or the poll loop should
541 	 * pick up any changes and fire the hotplug event. But if
542 	 * userspace sneaks in a probe, we might miss a change. Hence
543 	 * check here, and if anything changed start the hotplug code.
544 	 */
545 	if (old_status != connector->status) {
546 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
547 			      connector->base.id,
548 			      connector->name,
549 			      drm_get_connector_status_name(old_status),
550 			      drm_get_connector_status_name(connector->status));
551 
552 		/*
553 		 * The hotplug event code might call into the fb
554 		 * helpers, and so expects that we do not hold any
555 		 * locks. Fire up the poll struct instead, it will
556 		 * disable itself again.
557 		 */
558 		dev->mode_config.delayed_event = true;
559 		if (dev->mode_config.poll_enabled)
560 			schedule_delayed_work(&dev->mode_config.output_poll_work,
561 					      0);
562 	}
563 
564 	/* Re-enable polling in case the global poll config changed. */
565 	if (drm_kms_helper_poll != dev->mode_config.poll_running)
566 		drm_kms_helper_poll_enable(dev);
567 
568 	dev->mode_config.poll_running = drm_kms_helper_poll;
569 
570 	if (connector->status == connector_status_disconnected) {
571 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
572 			connector->base.id, connector->name);
573 		drm_connector_update_edid_property(connector, NULL);
574 		drm_mode_prune_invalid(dev, &connector->modes, false);
575 		goto exit;
576 	}
577 
578 	count = drm_helper_probe_get_modes(connector);
579 
580 	if (count == 0 && (connector->status == connector_status_connected ||
581 			   connector->status == connector_status_unknown)) {
582 		count = drm_add_modes_noedid(connector, 1024, 768);
583 
584 		/*
585 		 * Section 4.2.2.6 (EDID Corruption Detection) of the DP 1.4a
586 		 * Link CTS specifies that 640x480 (the official "failsafe"
587 		 * mode) needs to be the default if there's no EDID.
588 		 */
589 		if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort)
590 			drm_set_preferred_mode(connector, 640, 480);
591 	}
592 	count += drm_helper_probe_add_cmdline_mode(connector);
593 	if (count != 0) {
594 		ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
595 		if (ret == -EDEADLK) {
596 			drm_modeset_backoff(&ctx);
597 			goto retry;
598 		}
599 	}
600 
601 	drm_mode_prune_invalid(dev, &connector->modes, true);
602 
603 	/*
604 	 * Displayport spec section 5.2.1.2 ("Video Timing Format") says that
605 	 * all detachable sinks shall support 640x480 @60Hz as a fail safe
606 	 * mode. If all modes were pruned, perhaps because they need more
607 	 * lanes or a higher pixel clock than available, at least try to add
608 	 * in 640x480.
609 	 */
610 	if (list_empty(&connector->modes) &&
611 	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
612 		count = drm_add_modes_noedid(connector, 640, 480);
613 		ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
614 		if (ret == -EDEADLK) {
615 			drm_modeset_backoff(&ctx);
616 			goto retry;
617 		}
618 		drm_mode_prune_invalid(dev, &connector->modes, true);
619 	}
620 
621 exit:
622 	drm_modeset_drop_locks(&ctx);
623 	drm_modeset_acquire_fini(&ctx);
624 
625 	if (list_empty(&connector->modes))
626 		return 0;
627 
628 	drm_mode_sort(&connector->modes);
629 
630 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed modes :\n", connector->base.id,
631 			connector->name);
632 	list_for_each_entry(mode, &connector->modes, head) {
633 		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
634 		drm_mode_debug_printmodeline(mode);
635 	}
636 
637 	return count;
638 }
639 EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
640 
641 /**
642  * drm_kms_helper_hotplug_event - fire off KMS hotplug events
643  * @dev: drm_device whose connector state changed
644  *
645  * This function fires off the uevent for userspace and also calls the
646  * output_poll_changed function, which is most commonly used to inform the fbdev
647  * emulation code and allow it to update the fbcon output configuration.
648  *
649  * Drivers should call this from their hotplug handling code when a change is
650  * detected. Note that this function does not do any output detection of its
651  * own, like drm_helper_hpd_irq_event() does - this is assumed to be done by the
652  * driver already.
653  *
654  * This function must be called from process context with no mode
655  * setting locks held.
656  *
657  * If only a single connector has changed, consider calling
658  * drm_kms_helper_connector_hotplug_event() instead.
659  */
660 void drm_kms_helper_hotplug_event(struct drm_device *dev)
661 {
662 	/* send a uevent + call fbdev */
663 	drm_sysfs_hotplug_event(dev);
664 	if (dev->mode_config.funcs->output_poll_changed)
665 		dev->mode_config.funcs->output_poll_changed(dev);
666 
667 	drm_client_dev_hotplug(dev);
668 }
669 EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
670 
671 /**
672  * drm_kms_helper_connector_hotplug_event - fire off a KMS connector hotplug event
673  * @connector: drm_connector which has changed
674  *
675  * This is the same as drm_kms_helper_hotplug_event(), except it fires a more
676  * fine-grained uevent for a single connector.
677  */
678 void drm_kms_helper_connector_hotplug_event(struct drm_connector *connector)
679 {
680 	struct drm_device *dev = connector->dev;
681 
682 	/* send a uevent + call fbdev */
683 	drm_sysfs_connector_hotplug_event(connector);
684 	if (dev->mode_config.funcs->output_poll_changed)
685 		dev->mode_config.funcs->output_poll_changed(dev);
686 
687 	drm_client_dev_hotplug(dev);
688 }
689 EXPORT_SYMBOL(drm_kms_helper_connector_hotplug_event);
690 
691 static void output_poll_execute(struct work_struct *work)
692 {
693 	struct delayed_work *delayed_work = to_delayed_work(work);
694 	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
695 	struct drm_connector *connector;
696 	struct drm_connector_list_iter conn_iter;
697 	enum drm_connector_status old_status;
698 	bool repoll = false, changed;
699 	u64 old_epoch_counter;
700 
701 	if (!dev->mode_config.poll_enabled)
702 		return;
703 
704 	/* Pick up any changes detected by the probe functions. */
705 	changed = dev->mode_config.delayed_event;
706 	dev->mode_config.delayed_event = false;
707 
708 	if (!drm_kms_helper_poll)
709 		goto out;
710 
711 	if (!mutex_trylock(&dev->mode_config.mutex)) {
712 		repoll = true;
713 		goto out;
714 	}
715 
716 	drm_connector_list_iter_begin(dev, &conn_iter);
717 	drm_for_each_connector_iter(connector, &conn_iter) {
718 		/* Ignore forced connectors. */
719 		if (connector->force)
720 			continue;
721 
722 		/* Ignore HPD capable connectors and connectors where we don't
723 		 * want any hotplug detection at all for polling. */
724 		if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)
725 			continue;
726 
727 		old_status = connector->status;
728 		/* if we are connected and don't want to poll for disconnect
729 		   skip it */
730 		if (old_status == connector_status_connected &&
731 		    !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT))
732 			continue;
733 
734 		repoll = true;
735 
736 		old_epoch_counter = connector->epoch_counter;
737 		connector->status = drm_helper_probe_detect(connector, NULL, false);
738 		if (old_epoch_counter != connector->epoch_counter) {
739 			const char *old, *new;
740 
741 			/*
742 			 * The poll work sets force=false when calling detect so
743 			 * that drivers can avoid to do disruptive tests (e.g.
744 			 * when load detect cycles could cause flickering on
745 			 * other, running displays). This bears the risk that we
746 			 * flip-flop between unknown here in the poll work and
747 			 * the real state when userspace forces a full detect
748 			 * call after receiving a hotplug event due to this
749 			 * change.
750 			 *
751 			 * Hence clamp an unknown detect status to the old
752 			 * value.
753 			 */
754 			if (connector->status == connector_status_unknown) {
755 				connector->status = old_status;
756 				continue;
757 			}
758 
759 			old = drm_get_connector_status_name(old_status);
760 			new = drm_get_connector_status_name(connector->status);
761 
762 			DRM_DEBUG_KMS("[CONNECTOR:%d:%s] "
763 				      "status updated from %s to %s\n",
764 				      connector->base.id,
765 				      connector->name,
766 				      old, new);
767 			DRM_DEBUG_KMS("[CONNECTOR:%d:%s] epoch counter %llu -> %llu\n",
768 				      connector->base.id, connector->name,
769 				      old_epoch_counter, connector->epoch_counter);
770 
771 			changed = true;
772 		}
773 	}
774 	drm_connector_list_iter_end(&conn_iter);
775 
776 	mutex_unlock(&dev->mode_config.mutex);
777 
778 out:
779 	if (changed)
780 		drm_kms_helper_hotplug_event(dev);
781 
782 	if (repoll)
783 		schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
784 }
785 
786 /**
787  * drm_kms_helper_is_poll_worker - is %current task an output poll worker?
788  *
789  * Determine if %current task is an output poll worker.  This can be used
790  * to select distinct code paths for output polling versus other contexts.
791  *
792  * One use case is to avoid a deadlock between the output poll worker and
793  * the autosuspend worker wherein the latter waits for polling to finish
794  * upon calling drm_kms_helper_poll_disable(), while the former waits for
795  * runtime suspend to finish upon calling pm_runtime_get_sync() in a
796  * connector ->detect hook.
797  */
798 bool drm_kms_helper_is_poll_worker(void)
799 {
800 	struct work_struct *work = current_work();
801 
802 	return work && work->func == output_poll_execute;
803 }
804 EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
805 
806 /**
807  * drm_kms_helper_poll_disable - disable output polling
808  * @dev: drm_device
809  *
810  * This function disables the output polling work.
811  *
812  * Drivers can call this helper from their device suspend implementation. It is
813  * not an error to call this even when output polling isn't enabled or already
814  * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
815  *
816  * Note that calls to enable and disable polling must be strictly ordered, which
817  * is automatically the case when they're only call from suspend/resume
818  * callbacks.
819  */
820 void drm_kms_helper_poll_disable(struct drm_device *dev)
821 {
822 	if (!dev->mode_config.poll_enabled)
823 		return;
824 	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
825 }
826 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
827 
828 /**
829  * drm_kms_helper_poll_init - initialize and enable output polling
830  * @dev: drm_device
831  *
832  * This function initializes and then also enables output polling support for
833  * @dev. Drivers which do not have reliable hotplug support in hardware can use
834  * this helper infrastructure to regularly poll such connectors for changes in
835  * their connection state.
836  *
837  * Drivers can control which connectors are polled by setting the
838  * DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On
839  * connectors where probing live outputs can result in visual distortion drivers
840  * should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this.
841  * Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are
842  * completely ignored by the polling logic.
843  *
844  * Note that a connector can be both polled and probed from the hotplug handler,
845  * in case the hotplug interrupt is known to be unreliable.
846  */
847 void drm_kms_helper_poll_init(struct drm_device *dev)
848 {
849 	INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
850 	dev->mode_config.poll_enabled = true;
851 
852 	drm_kms_helper_poll_enable(dev);
853 }
854 EXPORT_SYMBOL(drm_kms_helper_poll_init);
855 
856 /**
857  * drm_kms_helper_poll_fini - disable output polling and clean it up
858  * @dev: drm_device
859  */
860 void drm_kms_helper_poll_fini(struct drm_device *dev)
861 {
862 	if (!dev->mode_config.poll_enabled)
863 		return;
864 
865 	dev->mode_config.poll_enabled = false;
866 	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
867 }
868 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
869 
870 static bool check_connector_changed(struct drm_connector *connector)
871 {
872 	struct drm_device *dev = connector->dev;
873 	enum drm_connector_status old_status;
874 	u64 old_epoch_counter;
875 
876 	/* Only handle HPD capable connectors. */
877 	drm_WARN_ON(dev, !(connector->polled & DRM_CONNECTOR_POLL_HPD));
878 
879 	drm_WARN_ON(dev, !mutex_is_locked(&dev->mode_config.mutex));
880 
881 	old_status = connector->status;
882 	old_epoch_counter = connector->epoch_counter;
883 	connector->status = drm_helper_probe_detect(connector, NULL, false);
884 
885 	if (old_epoch_counter == connector->epoch_counter) {
886 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Same epoch counter %llu\n",
887 			    connector->base.id,
888 			    connector->name,
889 			    connector->epoch_counter);
890 
891 		return false;
892 	}
893 
894 	drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s\n",
895 		    connector->base.id,
896 		    connector->name,
897 		    drm_get_connector_status_name(old_status),
898 		    drm_get_connector_status_name(connector->status));
899 
900 	drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Changed epoch counter %llu => %llu\n",
901 		    connector->base.id,
902 		    connector->name,
903 		    old_epoch_counter,
904 		    connector->epoch_counter);
905 
906 	return true;
907 }
908 
909 /**
910  * drm_connector_helper_hpd_irq_event - hotplug processing
911  * @connector: drm_connector
912  *
913  * Drivers can use this helper function to run a detect cycle on a connector
914  * which has the DRM_CONNECTOR_POLL_HPD flag set in its &polled member.
915  *
916  * This helper function is useful for drivers which can track hotplug
917  * interrupts for a single connector. Drivers that want to send a
918  * hotplug event for all connectors or can't track hotplug interrupts
919  * per connector need to use drm_helper_hpd_irq_event().
920  *
921  * This function must be called from process context with no mode
922  * setting locks held.
923  *
924  * Note that a connector can be both polled and probed from the hotplug
925  * handler, in case the hotplug interrupt is known to be unreliable.
926  *
927  * Returns:
928  * A boolean indicating whether the connector status changed or not
929  */
930 bool drm_connector_helper_hpd_irq_event(struct drm_connector *connector)
931 {
932 	struct drm_device *dev = connector->dev;
933 	bool changed;
934 
935 	mutex_lock(&dev->mode_config.mutex);
936 	changed = check_connector_changed(connector);
937 	mutex_unlock(&dev->mode_config.mutex);
938 
939 	if (changed) {
940 		drm_kms_helper_connector_hotplug_event(connector);
941 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Sent hotplug event\n",
942 			    connector->base.id,
943 			    connector->name);
944 	}
945 
946 	return changed;
947 }
948 EXPORT_SYMBOL(drm_connector_helper_hpd_irq_event);
949 
950 /**
951  * drm_helper_hpd_irq_event - hotplug processing
952  * @dev: drm_device
953  *
954  * Drivers can use this helper function to run a detect cycle on all connectors
955  * which have the DRM_CONNECTOR_POLL_HPD flag set in their &polled member. All
956  * other connectors are ignored, which is useful to avoid reprobing fixed
957  * panels.
958  *
959  * This helper function is useful for drivers which can't or don't track hotplug
960  * interrupts for each connector.
961  *
962  * Drivers which support hotplug interrupts for each connector individually and
963  * which have a more fine-grained detect logic can use
964  * drm_connector_helper_hpd_irq_event(). Alternatively, they should bypass this
965  * code and directly call drm_kms_helper_hotplug_event() in case the connector
966  * state changed.
967  *
968  * This function must be called from process context with no mode
969  * setting locks held.
970  *
971  * Note that a connector can be both polled and probed from the hotplug handler,
972  * in case the hotplug interrupt is known to be unreliable.
973  *
974  * Returns:
975  * A boolean indicating whether the connector status changed or not
976  */
977 bool drm_helper_hpd_irq_event(struct drm_device *dev)
978 {
979 	struct drm_connector *connector, *first_changed_connector = NULL;
980 	struct drm_connector_list_iter conn_iter;
981 	int changed = 0;
982 
983 	if (!dev->mode_config.poll_enabled)
984 		return false;
985 
986 	mutex_lock(&dev->mode_config.mutex);
987 	drm_connector_list_iter_begin(dev, &conn_iter);
988 	drm_for_each_connector_iter(connector, &conn_iter) {
989 		/* Only handle HPD capable connectors. */
990 		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
991 			continue;
992 
993 		if (check_connector_changed(connector)) {
994 			if (!first_changed_connector) {
995 				drm_connector_get(connector);
996 				first_changed_connector = connector;
997 			}
998 
999 			changed++;
1000 		}
1001 	}
1002 	drm_connector_list_iter_end(&conn_iter);
1003 	mutex_unlock(&dev->mode_config.mutex);
1004 
1005 	if (changed == 1)
1006 		drm_kms_helper_connector_hotplug_event(first_changed_connector);
1007 	else if (changed > 0)
1008 		drm_kms_helper_hotplug_event(dev);
1009 
1010 	if (first_changed_connector)
1011 		drm_connector_put(first_changed_connector);
1012 
1013 	return changed;
1014 }
1015 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
1016 
1017 /**
1018  * drm_connector_helper_get_modes_from_ddc - Updates the connector's EDID
1019  *                                           property from the connector's
1020  *                                           DDC channel
1021  * @connector: The connector
1022  *
1023  * Returns:
1024  * The number of detected display modes.
1025  *
1026  * Uses a connector's DDC channel to retrieve EDID data and update the
1027  * connector's EDID property and display modes. Drivers can use this
1028  * function to implement struct &drm_connector_helper_funcs.get_modes
1029  * for connectors with a DDC channel.
1030  */
1031 int drm_connector_helper_get_modes_from_ddc(struct drm_connector *connector)
1032 {
1033 	struct edid *edid;
1034 	int count = 0;
1035 
1036 	if (!connector->ddc)
1037 		return 0;
1038 
1039 	edid = drm_get_edid(connector, connector->ddc);
1040 
1041 	// clears property if EDID is NULL
1042 	drm_connector_update_edid_property(connector, edid);
1043 
1044 	if (edid) {
1045 		count = drm_add_edid_modes(connector, edid);
1046 		kfree(edid);
1047 	}
1048 
1049 	return count;
1050 }
1051 EXPORT_SYMBOL(drm_connector_helper_get_modes_from_ddc);
1052 
1053 /**
1054  * drm_connector_helper_get_modes - Read EDID and update connector.
1055  * @connector: The connector
1056  *
1057  * Read the EDID using drm_edid_read() (which requires that connector->ddc is
1058  * set), and update the connector using the EDID.
1059  *
1060  * This can be used as the "default" connector helper .get_modes() hook if the
1061  * driver does not need any special processing. This is sets the example what
1062  * custom .get_modes() hooks should do regarding EDID read and connector update.
1063  *
1064  * Returns: Number of modes.
1065  */
1066 int drm_connector_helper_get_modes(struct drm_connector *connector)
1067 {
1068 	const struct drm_edid *drm_edid;
1069 	int count;
1070 
1071 	drm_edid = drm_edid_read(connector);
1072 
1073 	/*
1074 	 * Unconditionally update the connector. If the EDID was read
1075 	 * successfully, fill in the connector information derived from the
1076 	 * EDID. Otherwise, if the EDID is NULL, clear the connector
1077 	 * information.
1078 	 */
1079 	count = drm_edid_connector_update(connector, drm_edid);
1080 
1081 	drm_edid_free(drm_edid);
1082 
1083 	return count;
1084 }
1085 EXPORT_SYMBOL(drm_connector_helper_get_modes);
1086