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 /**
358  * drm_helper_probe_single_connector_modes - get complete set of display modes
359  * @connector: connector to probe
360  * @maxX: max width for modes
361  * @maxY: max height for modes
362  *
363  * Based on the helper callbacks implemented by @connector in struct
364  * &drm_connector_helper_funcs try to detect all valid modes.  Modes will first
365  * be added to the connector's probed_modes list, then culled (based on validity
366  * and the @maxX, @maxY parameters) and put into the normal modes list.
367  *
368  * Intended to be used as a generic implementation of the
369  * &drm_connector_funcs.fill_modes() vfunc for drivers that use the CRTC helpers
370  * for output mode filtering and detection.
371  *
372  * The basic procedure is as follows
373  *
374  * 1. All modes currently on the connector's modes list are marked as stale
375  *
376  * 2. New modes are added to the connector's probed_modes list with
377  *    drm_mode_probed_add(). New modes start their life with status as OK.
378  *    Modes are added from a single source using the following priority order.
379  *
380  *    - &drm_connector_helper_funcs.get_modes vfunc
381  *    - if the connector status is connector_status_connected, standard
382  *      VESA DMT modes up to 1024x768 are automatically added
383  *      (drm_add_modes_noedid())
384  *
385  *    Finally modes specified via the kernel command line (video=...) are
386  *    added in addition to what the earlier probes produced
387  *    (drm_helper_probe_add_cmdline_mode()). These modes are generated
388  *    using the VESA GTF/CVT formulas.
389  *
390  * 3. Modes are moved from the probed_modes list to the modes list. Potential
391  *    duplicates are merged together (see drm_connector_list_update()).
392  *    After this step the probed_modes list will be empty again.
393  *
394  * 4. Any non-stale mode on the modes list then undergoes validation
395  *
396  *    - drm_mode_validate_basic() performs basic sanity checks
397  *    - drm_mode_validate_size() filters out modes larger than @maxX and @maxY
398  *      (if specified)
399  *    - drm_mode_validate_flag() checks the modes against basic connector
400  *      capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
401  *    - the optional &drm_connector_helper_funcs.mode_valid or
402  *      &drm_connector_helper_funcs.mode_valid_ctx helpers can perform driver
403  *      and/or sink specific checks
404  *    - the optional &drm_crtc_helper_funcs.mode_valid,
405  *      &drm_bridge_funcs.mode_valid and &drm_encoder_helper_funcs.mode_valid
406  *      helpers can perform driver and/or source specific checks which are also
407  *      enforced by the modeset/atomic helpers
408  *
409  * 5. Any mode whose status is not OK is pruned from the connector's modes list,
410  *    accompanied by a debug message indicating the reason for the mode's
411  *    rejection (see drm_mode_prune_invalid()).
412  *
413  * Returns:
414  * The number of modes found on @connector.
415  */
416 int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
417 					    uint32_t maxX, uint32_t maxY)
418 {
419 	struct drm_device *dev = connector->dev;
420 	struct drm_display_mode *mode;
421 	const struct drm_connector_helper_funcs *connector_funcs =
422 		connector->helper_private;
423 	int count = 0, ret;
424 	int mode_flags = 0;
425 	bool verbose_prune = true;
426 	enum drm_connector_status old_status;
427 	struct drm_modeset_acquire_ctx ctx;
428 
429 	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
430 
431 	drm_modeset_acquire_init(&ctx, 0);
432 
433 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
434 			connector->name);
435 
436 retry:
437 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
438 	if (ret == -EDEADLK) {
439 		drm_modeset_backoff(&ctx);
440 		goto retry;
441 	} else
442 		WARN_ON(ret < 0);
443 
444 	/* set all old modes to the stale state */
445 	list_for_each_entry(mode, &connector->modes, head)
446 		mode->status = MODE_STALE;
447 
448 	old_status = connector->status;
449 
450 	if (connector->force) {
451 		if (connector->force == DRM_FORCE_ON ||
452 		    connector->force == DRM_FORCE_ON_DIGITAL)
453 			connector->status = connector_status_connected;
454 		else
455 			connector->status = connector_status_disconnected;
456 		if (connector->funcs->force)
457 			connector->funcs->force(connector);
458 	} else {
459 		ret = drm_helper_probe_detect(connector, &ctx, true);
460 
461 		if (ret == -EDEADLK) {
462 			drm_modeset_backoff(&ctx);
463 			goto retry;
464 		} else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
465 			ret = connector_status_unknown;
466 
467 		connector->status = ret;
468 	}
469 
470 	/*
471 	 * Normally either the driver's hpd code or the poll loop should
472 	 * pick up any changes and fire the hotplug event. But if
473 	 * userspace sneaks in a probe, we might miss a change. Hence
474 	 * check here, and if anything changed start the hotplug code.
475 	 */
476 	if (old_status != connector->status) {
477 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
478 			      connector->base.id,
479 			      connector->name,
480 			      drm_get_connector_status_name(old_status),
481 			      drm_get_connector_status_name(connector->status));
482 
483 		/*
484 		 * The hotplug event code might call into the fb
485 		 * helpers, and so expects that we do not hold any
486 		 * locks. Fire up the poll struct instead, it will
487 		 * disable itself again.
488 		 */
489 		dev->mode_config.delayed_event = true;
490 		if (dev->mode_config.poll_enabled)
491 			schedule_delayed_work(&dev->mode_config.output_poll_work,
492 					      0);
493 	}
494 
495 	/* Re-enable polling in case the global poll config changed. */
496 	if (drm_kms_helper_poll != dev->mode_config.poll_running)
497 		drm_kms_helper_poll_enable(dev);
498 
499 	dev->mode_config.poll_running = drm_kms_helper_poll;
500 
501 	if (connector->status == connector_status_disconnected) {
502 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
503 			connector->base.id, connector->name);
504 		drm_connector_update_edid_property(connector, NULL);
505 		verbose_prune = false;
506 		goto prune;
507 	}
508 
509 	count = (*connector_funcs->get_modes)(connector);
510 
511 	/*
512 	 * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
513 	 * override/firmware EDID.
514 	 */
515 	if (count == 0 && connector->status == connector_status_connected)
516 		count = drm_add_override_edid_modes(connector);
517 
518 	if (count == 0 && (connector->status == connector_status_connected ||
519 			   connector->status == connector_status_unknown))
520 		count = drm_add_modes_noedid(connector, 1024, 768);
521 	count += drm_helper_probe_add_cmdline_mode(connector);
522 	if (count == 0)
523 		goto prune;
524 
525 	drm_connector_list_update(connector);
526 
527 	if (connector->interlace_allowed)
528 		mode_flags |= DRM_MODE_FLAG_INTERLACE;
529 	if (connector->doublescan_allowed)
530 		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
531 	if (connector->stereo_allowed)
532 		mode_flags |= DRM_MODE_FLAG_3D_MASK;
533 
534 	list_for_each_entry(mode, &connector->modes, head) {
535 		if (mode->status != MODE_OK)
536 			continue;
537 
538 		mode->status = drm_mode_validate_driver(dev, mode);
539 		if (mode->status != MODE_OK)
540 			continue;
541 
542 		mode->status = drm_mode_validate_size(mode, maxX, maxY);
543 		if (mode->status != MODE_OK)
544 			continue;
545 
546 		mode->status = drm_mode_validate_flag(mode, mode_flags);
547 		if (mode->status != MODE_OK)
548 			continue;
549 
550 		ret = drm_mode_validate_pipeline(mode, connector, &ctx,
551 						 &mode->status);
552 		if (ret) {
553 			drm_dbg_kms(dev,
554 				    "drm_mode_validate_pipeline failed: %d\n",
555 				    ret);
556 
557 			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK)) {
558 				mode->status = MODE_ERROR;
559 			} else {
560 				drm_modeset_backoff(&ctx);
561 				goto retry;
562 			}
563 		}
564 
565 		if (mode->status != MODE_OK)
566 			continue;
567 		mode->status = drm_mode_validate_ycbcr420(mode, connector);
568 	}
569 
570 prune:
571 	drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
572 
573 	drm_modeset_drop_locks(&ctx);
574 	drm_modeset_acquire_fini(&ctx);
575 
576 	if (list_empty(&connector->modes))
577 		return 0;
578 
579 	drm_mode_sort(&connector->modes);
580 
581 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed modes :\n", connector->base.id,
582 			connector->name);
583 	list_for_each_entry(mode, &connector->modes, head) {
584 		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
585 		drm_mode_debug_printmodeline(mode);
586 	}
587 
588 	return count;
589 }
590 EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
591 
592 /**
593  * drm_kms_helper_hotplug_event - fire off KMS hotplug events
594  * @dev: drm_device whose connector state changed
595  *
596  * This function fires off the uevent for userspace and also calls the
597  * output_poll_changed function, which is most commonly used to inform the fbdev
598  * emulation code and allow it to update the fbcon output configuration.
599  *
600  * Drivers should call this from their hotplug handling code when a change is
601  * detected. Note that this function does not do any output detection of its
602  * own, like drm_helper_hpd_irq_event() does - this is assumed to be done by the
603  * driver already.
604  *
605  * This function must be called from process context with no mode
606  * setting locks held.
607  */
608 void drm_kms_helper_hotplug_event(struct drm_device *dev)
609 {
610 	/* send a uevent + call fbdev */
611 	drm_sysfs_hotplug_event(dev);
612 	if (dev->mode_config.funcs->output_poll_changed)
613 		dev->mode_config.funcs->output_poll_changed(dev);
614 
615 	drm_client_dev_hotplug(dev);
616 }
617 EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
618 
619 static void output_poll_execute(struct work_struct *work)
620 {
621 	struct delayed_work *delayed_work = to_delayed_work(work);
622 	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
623 	struct drm_connector *connector;
624 	struct drm_connector_list_iter conn_iter;
625 	enum drm_connector_status old_status;
626 	bool repoll = false, changed;
627 
628 	if (!dev->mode_config.poll_enabled)
629 		return;
630 
631 	/* Pick up any changes detected by the probe functions. */
632 	changed = dev->mode_config.delayed_event;
633 	dev->mode_config.delayed_event = false;
634 
635 	if (!drm_kms_helper_poll)
636 		goto out;
637 
638 	if (!mutex_trylock(&dev->mode_config.mutex)) {
639 		repoll = true;
640 		goto out;
641 	}
642 
643 	drm_connector_list_iter_begin(dev, &conn_iter);
644 	drm_for_each_connector_iter(connector, &conn_iter) {
645 		/* Ignore forced connectors. */
646 		if (connector->force)
647 			continue;
648 
649 		/* Ignore HPD capable connectors and connectors where we don't
650 		 * want any hotplug detection at all for polling. */
651 		if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)
652 			continue;
653 
654 		old_status = connector->status;
655 		/* if we are connected and don't want to poll for disconnect
656 		   skip it */
657 		if (old_status == connector_status_connected &&
658 		    !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT))
659 			continue;
660 
661 		repoll = true;
662 
663 		connector->status = drm_helper_probe_detect(connector, NULL, false);
664 		if (old_status != connector->status) {
665 			const char *old, *new;
666 
667 			/*
668 			 * The poll work sets force=false when calling detect so
669 			 * that drivers can avoid to do disruptive tests (e.g.
670 			 * when load detect cycles could cause flickering on
671 			 * other, running displays). This bears the risk that we
672 			 * flip-flop between unknown here in the poll work and
673 			 * the real state when userspace forces a full detect
674 			 * call after receiving a hotplug event due to this
675 			 * change.
676 			 *
677 			 * Hence clamp an unknown detect status to the old
678 			 * value.
679 			 */
680 			if (connector->status == connector_status_unknown) {
681 				connector->status = old_status;
682 				continue;
683 			}
684 
685 			old = drm_get_connector_status_name(old_status);
686 			new = drm_get_connector_status_name(connector->status);
687 
688 			DRM_DEBUG_KMS("[CONNECTOR:%d:%s] "
689 				      "status updated from %s to %s\n",
690 				      connector->base.id,
691 				      connector->name,
692 				      old, new);
693 
694 			changed = true;
695 		}
696 	}
697 	drm_connector_list_iter_end(&conn_iter);
698 
699 	mutex_unlock(&dev->mode_config.mutex);
700 
701 out:
702 	if (changed)
703 		drm_kms_helper_hotplug_event(dev);
704 
705 	if (repoll)
706 		schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
707 }
708 
709 /**
710  * drm_kms_helper_is_poll_worker - is %current task an output poll worker?
711  *
712  * Determine if %current task is an output poll worker.  This can be used
713  * to select distinct code paths for output polling versus other contexts.
714  *
715  * One use case is to avoid a deadlock between the output poll worker and
716  * the autosuspend worker wherein the latter waits for polling to finish
717  * upon calling drm_kms_helper_poll_disable(), while the former waits for
718  * runtime suspend to finish upon calling pm_runtime_get_sync() in a
719  * connector ->detect hook.
720  */
721 bool drm_kms_helper_is_poll_worker(void)
722 {
723 	struct work_struct *work = current_work();
724 
725 	return work && work->func == output_poll_execute;
726 }
727 EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
728 
729 /**
730  * drm_kms_helper_poll_disable - disable output polling
731  * @dev: drm_device
732  *
733  * This function disables the output polling work.
734  *
735  * Drivers can call this helper from their device suspend implementation. It is
736  * not an error to call this even when output polling isn't enabled or already
737  * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
738  *
739  * Note that calls to enable and disable polling must be strictly ordered, which
740  * is automatically the case when they're only call from suspend/resume
741  * callbacks.
742  */
743 void drm_kms_helper_poll_disable(struct drm_device *dev)
744 {
745 	if (!dev->mode_config.poll_enabled)
746 		return;
747 	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
748 }
749 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
750 
751 /**
752  * drm_kms_helper_poll_init - initialize and enable output polling
753  * @dev: drm_device
754  *
755  * This function intializes and then also enables output polling support for
756  * @dev. Drivers which do not have reliable hotplug support in hardware can use
757  * this helper infrastructure to regularly poll such connectors for changes in
758  * their connection state.
759  *
760  * Drivers can control which connectors are polled by setting the
761  * DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On
762  * connectors where probing live outputs can result in visual distortion drivers
763  * should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this.
764  * Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are
765  * completely ignored by the polling logic.
766  *
767  * Note that a connector can be both polled and probed from the hotplug handler,
768  * in case the hotplug interrupt is known to be unreliable.
769  */
770 void drm_kms_helper_poll_init(struct drm_device *dev)
771 {
772 	INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
773 	dev->mode_config.poll_enabled = true;
774 
775 	drm_kms_helper_poll_enable(dev);
776 }
777 EXPORT_SYMBOL(drm_kms_helper_poll_init);
778 
779 /**
780  * drm_kms_helper_poll_fini - disable output polling and clean it up
781  * @dev: drm_device
782  */
783 void drm_kms_helper_poll_fini(struct drm_device *dev)
784 {
785 	if (!dev->mode_config.poll_enabled)
786 		return;
787 
788 	dev->mode_config.poll_enabled = false;
789 	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
790 }
791 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
792 
793 /**
794  * drm_helper_hpd_irq_event - hotplug processing
795  * @dev: drm_device
796  *
797  * Drivers can use this helper function to run a detect cycle on all connectors
798  * which have the DRM_CONNECTOR_POLL_HPD flag set in their &polled member. All
799  * other connectors are ignored, which is useful to avoid reprobing fixed
800  * panels.
801  *
802  * This helper function is useful for drivers which can't or don't track hotplug
803  * interrupts for each connector.
804  *
805  * Drivers which support hotplug interrupts for each connector individually and
806  * which have a more fine-grained detect logic should bypass this code and
807  * directly call drm_kms_helper_hotplug_event() in case the connector state
808  * changed.
809  *
810  * This function must be called from process context with no mode
811  * setting locks held.
812  *
813  * Note that a connector can be both polled and probed from the hotplug handler,
814  * in case the hotplug interrupt is known to be unreliable.
815  */
816 bool drm_helper_hpd_irq_event(struct drm_device *dev)
817 {
818 	struct drm_connector *connector;
819 	struct drm_connector_list_iter conn_iter;
820 	enum drm_connector_status old_status;
821 	bool changed = false;
822 	u64 old_epoch_counter;
823 
824 	if (!dev->mode_config.poll_enabled)
825 		return false;
826 
827 	mutex_lock(&dev->mode_config.mutex);
828 	drm_connector_list_iter_begin(dev, &conn_iter);
829 	drm_for_each_connector_iter(connector, &conn_iter) {
830 		/* Only handle HPD capable connectors. */
831 		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
832 			continue;
833 
834 		old_status = connector->status;
835 
836 		old_epoch_counter = connector->epoch_counter;
837 
838 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Old epoch counter %llu\n", connector->base.id,
839 			      connector->name,
840 			      old_epoch_counter);
841 
842 		connector->status = drm_helper_probe_detect(connector, NULL, false);
843 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
844 			      connector->base.id,
845 			      connector->name,
846 			      drm_get_connector_status_name(old_status),
847 			      drm_get_connector_status_name(connector->status));
848 
849 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] New epoch counter %llu\n",
850 			      connector->base.id,
851 			      connector->name,
852 			      connector->epoch_counter);
853 
854 		/*
855 		 * Check if epoch counter had changed, meaning that we need
856 		 * to send a uevent.
857 		 */
858 		if (old_epoch_counter != connector->epoch_counter)
859 			changed = true;
860 
861 	}
862 	drm_connector_list_iter_end(&conn_iter);
863 	mutex_unlock(&dev->mode_config.mutex);
864 
865 	if (changed) {
866 		drm_kms_helper_hotplug_event(dev);
867 		DRM_DEBUG_KMS("Sent hotplug event\n");
868 	}
869 
870 	return changed;
871 }
872 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
873