xref: /linux/drivers/gpu/drm/drm_atomic_state_helper.c (revision dec1c62e91ba268ab2a6e339d4d7a59287d5eba1)
1 /*
2  * Copyright (C) 2018 Intel Corp.
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:
23  * Rob Clark <robdclark@gmail.com>
24  * Daniel Vetter <daniel.vetter@ffwll.ch>
25  */
26 
27 #include <drm/drm_atomic.h>
28 #include <drm/drm_atomic_state_helper.h>
29 #include <drm/drm_bridge.h>
30 #include <drm/drm_connector.h>
31 #include <drm/drm_crtc.h>
32 #include <drm/drm_device.h>
33 #include <drm/drm_plane.h>
34 #include <drm/drm_print.h>
35 #include <drm/drm_vblank.h>
36 #include <drm/drm_writeback.h>
37 
38 #include <linux/slab.h>
39 #include <linux/dma-fence.h>
40 
41 /**
42  * DOC: atomic state reset and initialization
43  *
44  * Both the drm core and the atomic helpers assume that there is always the full
45  * and correct atomic software state for all connectors, CRTCs and planes
46  * available. Which is a bit a problem on driver load and also after system
47  * suspend. One way to solve this is to have a hardware state read-out
48  * infrastructure which reconstructs the full software state (e.g. the i915
49  * driver).
50  *
51  * The simpler solution is to just reset the software state to everything off,
52  * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
53  * the atomic helpers provide default reset implementations for all hooks.
54  *
55  * On the upside the precise state tracking of atomic simplifies system suspend
56  * and resume a lot. For drivers using drm_mode_config_reset() a complete recipe
57  * is implemented in drm_atomic_helper_suspend() and drm_atomic_helper_resume().
58  * For other drivers the building blocks are split out, see the documentation
59  * for these functions.
60  */
61 
62 /**
63  * __drm_atomic_helper_crtc_state_reset - reset the CRTC state
64  * @crtc_state: atomic CRTC state, must not be NULL
65  * @crtc: CRTC object, must not be NULL
66  *
67  * Initializes the newly allocated @crtc_state with default
68  * values. This is useful for drivers that subclass the CRTC state.
69  */
70 void
71 __drm_atomic_helper_crtc_state_reset(struct drm_crtc_state *crtc_state,
72 				     struct drm_crtc *crtc)
73 {
74 	crtc_state->crtc = crtc;
75 }
76 EXPORT_SYMBOL(__drm_atomic_helper_crtc_state_reset);
77 
78 /**
79  * __drm_atomic_helper_crtc_reset - reset state on CRTC
80  * @crtc: drm CRTC
81  * @crtc_state: CRTC state to assign
82  *
83  * Initializes the newly allocated @crtc_state and assigns it to
84  * the &drm_crtc->state pointer of @crtc, usually required when
85  * initializing the drivers or when called from the &drm_crtc_funcs.reset
86  * hook.
87  *
88  * This is useful for drivers that subclass the CRTC state.
89  */
90 void
91 __drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
92 			       struct drm_crtc_state *crtc_state)
93 {
94 	if (crtc_state)
95 		__drm_atomic_helper_crtc_state_reset(crtc_state, crtc);
96 
97 	if (drm_dev_has_vblank(crtc->dev))
98 		drm_crtc_vblank_reset(crtc);
99 
100 	crtc->state = crtc_state;
101 }
102 EXPORT_SYMBOL(__drm_atomic_helper_crtc_reset);
103 
104 /**
105  * drm_atomic_helper_crtc_reset - default &drm_crtc_funcs.reset hook for CRTCs
106  * @crtc: drm CRTC
107  *
108  * Resets the atomic state for @crtc by freeing the state pointer (which might
109  * be NULL, e.g. at driver load time) and allocating a new empty state object.
110  */
111 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
112 {
113 	struct drm_crtc_state *crtc_state =
114 		kzalloc(sizeof(*crtc->state), GFP_KERNEL);
115 
116 	if (crtc->state)
117 		crtc->funcs->atomic_destroy_state(crtc, crtc->state);
118 
119 	__drm_atomic_helper_crtc_reset(crtc, crtc_state);
120 }
121 EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);
122 
123 /**
124  * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
125  * @crtc: CRTC object
126  * @state: atomic CRTC state
127  *
128  * Copies atomic state from a CRTC's current state and resets inferred values.
129  * This is useful for drivers that subclass the CRTC state.
130  */
131 void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
132 					      struct drm_crtc_state *state)
133 {
134 	memcpy(state, crtc->state, sizeof(*state));
135 
136 	if (state->mode_blob)
137 		drm_property_blob_get(state->mode_blob);
138 	if (state->degamma_lut)
139 		drm_property_blob_get(state->degamma_lut);
140 	if (state->ctm)
141 		drm_property_blob_get(state->ctm);
142 	if (state->gamma_lut)
143 		drm_property_blob_get(state->gamma_lut);
144 	state->mode_changed = false;
145 	state->active_changed = false;
146 	state->planes_changed = false;
147 	state->connectors_changed = false;
148 	state->color_mgmt_changed = false;
149 	state->zpos_changed = false;
150 	state->commit = NULL;
151 	state->event = NULL;
152 	state->async_flip = false;
153 
154 	/* Self refresh should be canceled when a new update is available */
155 	state->active = drm_atomic_crtc_effectively_active(state);
156 	state->self_refresh_active = false;
157 }
158 EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);
159 
160 /**
161  * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
162  * @crtc: drm CRTC
163  *
164  * Default CRTC state duplicate hook for drivers which don't have their own
165  * subclassed CRTC state structure.
166  */
167 struct drm_crtc_state *
168 drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
169 {
170 	struct drm_crtc_state *state;
171 
172 	if (WARN_ON(!crtc->state))
173 		return NULL;
174 
175 	state = kmalloc(sizeof(*state), GFP_KERNEL);
176 	if (state)
177 		__drm_atomic_helper_crtc_duplicate_state(crtc, state);
178 
179 	return state;
180 }
181 EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);
182 
183 /**
184  * __drm_atomic_helper_crtc_destroy_state - release CRTC state
185  * @state: CRTC state object to release
186  *
187  * Releases all resources stored in the CRTC state without actually freeing
188  * the memory of the CRTC state. This is useful for drivers that subclass the
189  * CRTC state.
190  */
191 void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state)
192 {
193 	if (state->commit) {
194 		/*
195 		 * In the event that a non-blocking commit returns
196 		 * -ERESTARTSYS before the commit_tail work is queued, we will
197 		 * have an extra reference to the commit object. Release it, if
198 		 * the event has not been consumed by the worker.
199 		 *
200 		 * state->event may be freed, so we can't directly look at
201 		 * state->event->base.completion.
202 		 */
203 		if (state->event && state->commit->abort_completion)
204 			drm_crtc_commit_put(state->commit);
205 
206 		kfree(state->commit->event);
207 		state->commit->event = NULL;
208 
209 		drm_crtc_commit_put(state->commit);
210 	}
211 
212 	drm_property_blob_put(state->mode_blob);
213 	drm_property_blob_put(state->degamma_lut);
214 	drm_property_blob_put(state->ctm);
215 	drm_property_blob_put(state->gamma_lut);
216 }
217 EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);
218 
219 /**
220  * drm_atomic_helper_crtc_destroy_state - default state destroy hook
221  * @crtc: drm CRTC
222  * @state: CRTC state object to release
223  *
224  * Default CRTC state destroy hook for drivers which don't have their own
225  * subclassed CRTC state structure.
226  */
227 void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
228 					  struct drm_crtc_state *state)
229 {
230 	__drm_atomic_helper_crtc_destroy_state(state);
231 	kfree(state);
232 }
233 EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);
234 
235 /**
236  * __drm_atomic_helper_plane_state_reset - resets plane state to default values
237  * @plane_state: atomic plane state, must not be NULL
238  * @plane: plane object, must not be NULL
239  *
240  * Initializes the newly allocated @plane_state with default
241  * values. This is useful for drivers that subclass the CRTC state.
242  */
243 void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,
244 					   struct drm_plane *plane)
245 {
246 	u64 val;
247 
248 	plane_state->plane = plane;
249 	plane_state->rotation = DRM_MODE_ROTATE_0;
250 
251 	plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
252 	plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
253 
254 	if (plane->color_encoding_property) {
255 		if (!drm_object_property_get_default_value(&plane->base,
256 							   plane->color_encoding_property,
257 							   &val))
258 			plane_state->color_encoding = val;
259 	}
260 
261 	if (plane->color_range_property) {
262 		if (!drm_object_property_get_default_value(&plane->base,
263 							   plane->color_range_property,
264 							   &val))
265 			plane_state->color_range = val;
266 	}
267 
268 	if (plane->zpos_property) {
269 		if (!drm_object_property_get_default_value(&plane->base,
270 							   plane->zpos_property,
271 							   &val)) {
272 			plane_state->zpos = val;
273 			plane_state->normalized_zpos = val;
274 		}
275 	}
276 }
277 EXPORT_SYMBOL(__drm_atomic_helper_plane_state_reset);
278 
279 /**
280  * __drm_atomic_helper_plane_reset - reset state on plane
281  * @plane: drm plane
282  * @plane_state: plane state to assign
283  *
284  * Initializes the newly allocated @plane_state and assigns it to
285  * the &drm_crtc->state pointer of @plane, usually required when
286  * initializing the drivers or when called from the &drm_plane_funcs.reset
287  * hook.
288  *
289  * This is useful for drivers that subclass the plane state.
290  */
291 void __drm_atomic_helper_plane_reset(struct drm_plane *plane,
292 				     struct drm_plane_state *plane_state)
293 {
294 	if (plane_state)
295 		__drm_atomic_helper_plane_state_reset(plane_state, plane);
296 
297 	plane->state = plane_state;
298 }
299 EXPORT_SYMBOL(__drm_atomic_helper_plane_reset);
300 
301 /**
302  * drm_atomic_helper_plane_reset - default &drm_plane_funcs.reset hook for planes
303  * @plane: drm plane
304  *
305  * Resets the atomic state for @plane by freeing the state pointer (which might
306  * be NULL, e.g. at driver load time) and allocating a new empty state object.
307  */
308 void drm_atomic_helper_plane_reset(struct drm_plane *plane)
309 {
310 	if (plane->state)
311 		__drm_atomic_helper_plane_destroy_state(plane->state);
312 
313 	kfree(plane->state);
314 	plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);
315 	if (plane->state)
316 		__drm_atomic_helper_plane_reset(plane, plane->state);
317 }
318 EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
319 
320 /**
321  * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
322  * @plane: plane object
323  * @state: atomic plane state
324  *
325  * Copies atomic state from a plane's current state. This is useful for
326  * drivers that subclass the plane state.
327  */
328 void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
329 					       struct drm_plane_state *state)
330 {
331 	memcpy(state, plane->state, sizeof(*state));
332 
333 	if (state->fb)
334 		drm_framebuffer_get(state->fb);
335 
336 	state->fence = NULL;
337 	state->commit = NULL;
338 	state->fb_damage_clips = NULL;
339 }
340 EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);
341 
342 /**
343  * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
344  * @plane: drm plane
345  *
346  * Default plane state duplicate hook for drivers which don't have their own
347  * subclassed plane state structure.
348  */
349 struct drm_plane_state *
350 drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
351 {
352 	struct drm_plane_state *state;
353 
354 	if (WARN_ON(!plane->state))
355 		return NULL;
356 
357 	state = kmalloc(sizeof(*state), GFP_KERNEL);
358 	if (state)
359 		__drm_atomic_helper_plane_duplicate_state(plane, state);
360 
361 	return state;
362 }
363 EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);
364 
365 /**
366  * __drm_atomic_helper_plane_destroy_state - release plane state
367  * @state: plane state object to release
368  *
369  * Releases all resources stored in the plane state without actually freeing
370  * the memory of the plane state. This is useful for drivers that subclass the
371  * plane state.
372  */
373 void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
374 {
375 	if (state->fb)
376 		drm_framebuffer_put(state->fb);
377 
378 	if (state->fence)
379 		dma_fence_put(state->fence);
380 
381 	if (state->commit)
382 		drm_crtc_commit_put(state->commit);
383 
384 	drm_property_blob_put(state->fb_damage_clips);
385 }
386 EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
387 
388 /**
389  * drm_atomic_helper_plane_destroy_state - default state destroy hook
390  * @plane: drm plane
391  * @state: plane state object to release
392  *
393  * Default plane state destroy hook for drivers which don't have their own
394  * subclassed plane state structure.
395  */
396 void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
397 					   struct drm_plane_state *state)
398 {
399 	__drm_atomic_helper_plane_destroy_state(state);
400 	kfree(state);
401 }
402 EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);
403 
404 /**
405  * __drm_atomic_helper_connector_state_reset - reset the connector state
406  * @conn_state: atomic connector state, must not be NULL
407  * @connector: connectotr object, must not be NULL
408  *
409  * Initializes the newly allocated @conn_state with default
410  * values. This is useful for drivers that subclass the connector state.
411  */
412 void
413 __drm_atomic_helper_connector_state_reset(struct drm_connector_state *conn_state,
414 					  struct drm_connector *connector)
415 {
416 	conn_state->connector = connector;
417 }
418 EXPORT_SYMBOL(__drm_atomic_helper_connector_state_reset);
419 
420 /**
421  * __drm_atomic_helper_connector_reset - reset state on connector
422  * @connector: drm connector
423  * @conn_state: connector state to assign
424  *
425  * Initializes the newly allocated @conn_state and assigns it to
426  * the &drm_connector->state pointer of @connector, usually required when
427  * initializing the drivers or when called from the &drm_connector_funcs.reset
428  * hook.
429  *
430  * This is useful for drivers that subclass the connector state.
431  */
432 void
433 __drm_atomic_helper_connector_reset(struct drm_connector *connector,
434 				    struct drm_connector_state *conn_state)
435 {
436 	if (conn_state)
437 		__drm_atomic_helper_connector_state_reset(conn_state, connector);
438 
439 	connector->state = conn_state;
440 }
441 EXPORT_SYMBOL(__drm_atomic_helper_connector_reset);
442 
443 /**
444  * drm_atomic_helper_connector_reset - default &drm_connector_funcs.reset hook for connectors
445  * @connector: drm connector
446  *
447  * Resets the atomic state for @connector by freeing the state pointer (which
448  * might be NULL, e.g. at driver load time) and allocating a new empty state
449  * object.
450  */
451 void drm_atomic_helper_connector_reset(struct drm_connector *connector)
452 {
453 	struct drm_connector_state *conn_state =
454 		kzalloc(sizeof(*conn_state), GFP_KERNEL);
455 
456 	if (connector->state)
457 		__drm_atomic_helper_connector_destroy_state(connector->state);
458 
459 	kfree(connector->state);
460 	__drm_atomic_helper_connector_reset(connector, conn_state);
461 }
462 EXPORT_SYMBOL(drm_atomic_helper_connector_reset);
463 
464 /**
465  * drm_atomic_helper_connector_tv_reset - Resets TV connector properties
466  * @connector: DRM connector
467  *
468  * Resets the TV-related properties attached to a connector.
469  */
470 void drm_atomic_helper_connector_tv_reset(struct drm_connector *connector)
471 {
472 	struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
473 	struct drm_connector_state *state = connector->state;
474 
475 	state->tv.margins.left = cmdline->tv_margins.left;
476 	state->tv.margins.right = cmdline->tv_margins.right;
477 	state->tv.margins.top = cmdline->tv_margins.top;
478 	state->tv.margins.bottom = cmdline->tv_margins.bottom;
479 }
480 EXPORT_SYMBOL(drm_atomic_helper_connector_tv_reset);
481 
482 /**
483  * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
484  * @connector: connector object
485  * @state: atomic connector state
486  *
487  * Copies atomic state from a connector's current state. This is useful for
488  * drivers that subclass the connector state.
489  */
490 void
491 __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
492 					    struct drm_connector_state *state)
493 {
494 	memcpy(state, connector->state, sizeof(*state));
495 	if (state->crtc)
496 		drm_connector_get(connector);
497 	state->commit = NULL;
498 
499 	if (state->hdr_output_metadata)
500 		drm_property_blob_get(state->hdr_output_metadata);
501 
502 	/* Don't copy over a writeback job, they are used only once */
503 	state->writeback_job = NULL;
504 }
505 EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);
506 
507 /**
508  * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
509  * @connector: drm connector
510  *
511  * Default connector state duplicate hook for drivers which don't have their own
512  * subclassed connector state structure.
513  */
514 struct drm_connector_state *
515 drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
516 {
517 	struct drm_connector_state *state;
518 
519 	if (WARN_ON(!connector->state))
520 		return NULL;
521 
522 	state = kmalloc(sizeof(*state), GFP_KERNEL);
523 	if (state)
524 		__drm_atomic_helper_connector_duplicate_state(connector, state);
525 
526 	return state;
527 }
528 EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);
529 
530 /**
531  * __drm_atomic_helper_connector_destroy_state - release connector state
532  * @state: connector state object to release
533  *
534  * Releases all resources stored in the connector state without actually
535  * freeing the memory of the connector state. This is useful for drivers that
536  * subclass the connector state.
537  */
538 void
539 __drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
540 {
541 	if (state->crtc)
542 		drm_connector_put(state->connector);
543 
544 	if (state->commit)
545 		drm_crtc_commit_put(state->commit);
546 
547 	if (state->writeback_job)
548 		drm_writeback_cleanup_job(state->writeback_job);
549 
550 	drm_property_blob_put(state->hdr_output_metadata);
551 }
552 EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);
553 
554 /**
555  * drm_atomic_helper_connector_destroy_state - default state destroy hook
556  * @connector: drm connector
557  * @state: connector state object to release
558  *
559  * Default connector state destroy hook for drivers which don't have their own
560  * subclassed connector state structure.
561  */
562 void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
563 					  struct drm_connector_state *state)
564 {
565 	__drm_atomic_helper_connector_destroy_state(state);
566 	kfree(state);
567 }
568 EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
569 
570 /**
571  * __drm_atomic_helper_private_obj_duplicate_state - copy atomic private state
572  * @obj: CRTC object
573  * @state: new private object state
574  *
575  * Copies atomic state from a private objects's current state and resets inferred values.
576  * This is useful for drivers that subclass the private state.
577  */
578 void __drm_atomic_helper_private_obj_duplicate_state(struct drm_private_obj *obj,
579 						     struct drm_private_state *state)
580 {
581 	memcpy(state, obj->state, sizeof(*state));
582 }
583 EXPORT_SYMBOL(__drm_atomic_helper_private_obj_duplicate_state);
584 
585 /**
586  * __drm_atomic_helper_bridge_duplicate_state() - Copy atomic bridge state
587  * @bridge: bridge object
588  * @state: atomic bridge state
589  *
590  * Copies atomic state from a bridge's current state and resets inferred values.
591  * This is useful for drivers that subclass the bridge state.
592  */
593 void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge,
594 						struct drm_bridge_state *state)
595 {
596 	__drm_atomic_helper_private_obj_duplicate_state(&bridge->base,
597 							&state->base);
598 	state->bridge = bridge;
599 }
600 EXPORT_SYMBOL(__drm_atomic_helper_bridge_duplicate_state);
601 
602 /**
603  * drm_atomic_helper_bridge_duplicate_state() - Duplicate a bridge state object
604  * @bridge: bridge object
605  *
606  * Allocates a new bridge state and initializes it with the current bridge
607  * state values. This helper is meant to be used as a bridge
608  * &drm_bridge_funcs.atomic_duplicate_state hook for bridges that don't
609  * subclass the bridge state.
610  */
611 struct drm_bridge_state *
612 drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge)
613 {
614 	struct drm_bridge_state *new;
615 
616 	if (WARN_ON(!bridge->base.state))
617 		return NULL;
618 
619 	new = kzalloc(sizeof(*new), GFP_KERNEL);
620 	if (new)
621 		__drm_atomic_helper_bridge_duplicate_state(bridge, new);
622 
623 	return new;
624 }
625 EXPORT_SYMBOL(drm_atomic_helper_bridge_duplicate_state);
626 
627 /**
628  * drm_atomic_helper_bridge_destroy_state() - Destroy a bridge state object
629  * @bridge: the bridge this state refers to
630  * @state: bridge state to destroy
631  *
632  * Destroys a bridge state previously created by
633  * &drm_atomic_helper_bridge_reset() or
634  * &drm_atomic_helper_bridge_duplicate_state(). This helper is meant to be
635  * used as a bridge &drm_bridge_funcs.atomic_destroy_state hook for bridges
636  * that don't subclass the bridge state.
637  */
638 void drm_atomic_helper_bridge_destroy_state(struct drm_bridge *bridge,
639 					    struct drm_bridge_state *state)
640 {
641 	kfree(state);
642 }
643 EXPORT_SYMBOL(drm_atomic_helper_bridge_destroy_state);
644 
645 /**
646  * __drm_atomic_helper_bridge_reset() - Initialize a bridge state to its
647  *					default
648  * @bridge: the bridge this state refers to
649  * @state: bridge state to initialize
650  *
651  * Initializes the bridge state to default values. This is meant to be called
652  * by the bridge &drm_bridge_funcs.atomic_reset hook for bridges that subclass
653  * the bridge state.
654  */
655 void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge,
656 				      struct drm_bridge_state *state)
657 {
658 	memset(state, 0, sizeof(*state));
659 	state->bridge = bridge;
660 }
661 EXPORT_SYMBOL(__drm_atomic_helper_bridge_reset);
662 
663 /**
664  * drm_atomic_helper_bridge_reset() - Allocate and initialize a bridge state
665  *				      to its default
666  * @bridge: the bridge this state refers to
667  *
668  * Allocates the bridge state and initializes it to default values. This helper
669  * is meant to be used as a bridge &drm_bridge_funcs.atomic_reset hook for
670  * bridges that don't subclass the bridge state.
671  */
672 struct drm_bridge_state *
673 drm_atomic_helper_bridge_reset(struct drm_bridge *bridge)
674 {
675 	struct drm_bridge_state *bridge_state;
676 
677 	bridge_state = kzalloc(sizeof(*bridge_state), GFP_KERNEL);
678 	if (!bridge_state)
679 		return ERR_PTR(-ENOMEM);
680 
681 	__drm_atomic_helper_bridge_reset(bridge, bridge_state);
682 	return bridge_state;
683 }
684 EXPORT_SYMBOL(drm_atomic_helper_bridge_reset);
685