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