summaryrefslogtreecommitdiffstats
path: root/include/drm/drm_bridge.h
blob: 4baca0d9107b059a79e15949f0e831128cb0a573 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
/*
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#ifndef __DRM_BRIDGE_H__
#define __DRM_BRIDGE_H__

#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/mutex.h>

#include <drm/drm_atomic.h>
#include <drm/drm_encoder.h>
#include <drm/drm_mode_object.h>
#include <drm/drm_modes.h>

struct device_node;

struct drm_bridge;
struct drm_bridge_timings;
struct drm_connector;
struct drm_display_info;
struct drm_minor;
struct drm_panel;
struct edid;
struct i2c_adapter;

/**
 * enum drm_bridge_attach_flags - Flags for &drm_bridge_funcs.attach
 */
enum drm_bridge_attach_flags {
	/**
	 * @DRM_BRIDGE_ATTACH_NO_CONNECTOR: When this flag is set the bridge
	 * shall not create a drm_connector.
	 */
	DRM_BRIDGE_ATTACH_NO_CONNECTOR = BIT(0),
};

/**
 * struct drm_bridge_funcs - drm_bridge control functions
 */
struct drm_bridge_funcs {
	/**
	 * @attach:
	 *
	 * This callback is invoked whenever our bridge is being attached to a
	 * &drm_encoder. The flags argument tunes the behaviour of the attach
	 * operation (see DRM_BRIDGE_ATTACH_*).
	 *
	 * The @attach callback is optional.
	 *
	 * RETURNS:
	 *
	 * Zero on success, error code on failure.
	 */
	int (*attach)(struct drm_bridge *bridge,
		      enum drm_bridge_attach_flags flags);

	/**
	 * @detach:
	 *
	 * This callback is invoked whenever our bridge is being detached from a
	 * &drm_encoder.
	 *
	 * The @detach callback is optional.
	 */
	void (*detach)(struct drm_bridge *bridge);

	/**
	 * @mode_valid:
	 *
	 * This callback is used to check if a specific mode is valid in this
	 * bridge. This should be implemented if the bridge has some sort of
	 * restriction in the modes it can display. For example, a given bridge
	 * may be responsible to set a clock value. If the clock can not
	 * produce all the values for the available modes then this callback
	 * can be used to restrict the number of modes to only the ones that
	 * can be displayed.
	 *
	 * This hook is used by the probe helpers to filter the mode list in
	 * drm_helper_probe_single_connector_modes(), and it is used by the
	 * atomic helpers to validate modes supplied by userspace in
	 * drm_atomic_helper_check_modeset().
	 *
	 * The @mode_valid callback is optional.
	 *
	 * NOTE:
	 *
	 * Since this function is both called from the check phase of an atomic
	 * commit, and the mode validation in the probe paths it is not allowed
	 * to look at anything else but the passed-in mode, and validate it
	 * against configuration-invariant hardware constraints. Any further
	 * limits which depend upon the configuration can only be checked in
	 * @mode_fixup.
	 *
	 * RETURNS:
	 *
	 * drm_mode_status Enum
	 */
	enum drm_mode_status (*mode_valid)(struct drm_bridge *bridge,
					   const struct drm_display_info *info,
					   const struct drm_display_mode *mode);

	/**
	 * @mode_fixup:
	 *
	 * This callback is used to validate and adjust a mode. The parameter
	 * mode is the display mode that should be fed to the next element in
	 * the display chain, either the final &drm_connector or the next
	 * &drm_bridge. The parameter adjusted_mode is the input mode the bridge
	 * requires. It can be modified by this callback and does not need to
	 * match mode. See also &drm_crtc_state.adjusted_mode for more details.
	 *
	 * This is the only hook that allows a bridge to reject a modeset. If
	 * this function passes all other callbacks must succeed for this
	 * configuration.
	 *
	 * The mode_fixup callback is optional. &drm_bridge_funcs.mode_fixup()
	 * is not called when &drm_bridge_funcs.atomic_check() is implemented,
	 * so only one of them should be provided.
	 *
	 * NOTE:
	 *
	 * This function is called in the check phase of atomic modesets, which
	 * can be aborted for any reason (including on userspace's request to
	 * just check whether a configuration would be possible). Drivers MUST
	 * NOT touch any persistent state (hardware or software) or data
	 * structures except the passed in @state parameter.
	 *
	 * Also beware that userspace can request its own custom modes, neither
	 * core nor helpers filter modes to the list of probe modes reported by
	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
	 * that modes are filtered consistently put any bridge constraints and
	 * limits checks into @mode_valid.
	 *
	 * RETURNS:
	 *
	 * True if an acceptable configuration is possible, false if the modeset
	 * operation should be rejected.
	 */
	bool (*mode_fixup)(struct drm_bridge *bridge,
			   const struct drm_display_mode *mode,
			   struct drm_display_mode *adjusted_mode);
	/**
	 * @disable:
	 *
	 * This callback should disable the bridge. It is called right before
	 * the preceding element in the display pipe is disabled. If the
	 * preceding element is a bridge this means it's called before that
	 * bridge's @disable vfunc. If the preceding element is a &drm_encoder
	 * it's called right before the &drm_encoder_helper_funcs.disable,
	 * &drm_encoder_helper_funcs.prepare or &drm_encoder_helper_funcs.dpms
	 * hook.
	 *
	 * The bridge can assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is still running when this callback is called.
	 *
	 * The @disable callback is optional.
	 *
	 * NOTE:
	 *
	 * This is deprecated, do not use!
	 * New drivers shall use &drm_bridge_funcs.atomic_disable.
	 */
	void (*disable)(struct drm_bridge *bridge);

	/**
	 * @post_disable:
	 *
	 * This callback should disable the bridge. It is called right after the
	 * preceding element in the display pipe is disabled. If the preceding
	 * element is a bridge this means it's called after that bridge's
	 * @post_disable function. If the preceding element is a &drm_encoder
	 * it's called right after the encoder's
	 * &drm_encoder_helper_funcs.disable, &drm_encoder_helper_funcs.prepare
	 * or &drm_encoder_helper_funcs.dpms hook.
	 *
	 * The bridge must assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is no longer running when this callback is
	 * called.
	 *
	 * The @post_disable callback is optional.
	 *
	 * NOTE:
	 *
	 * This is deprecated, do not use!
	 * New drivers shall use &drm_bridge_funcs.atomic_post_disable.
	 */
	void (*post_disable)(struct drm_bridge *bridge);

	/**
	 * @mode_set:
	 *
	 * This callback should set the given mode on the bridge. It is called
	 * after the @mode_set callback for the preceding element in the display
	 * pipeline has been called already. If the bridge is the first element
	 * then this would be &drm_encoder_helper_funcs.mode_set. The display
	 * pipe (i.e.  clocks and timing signals) is off when this function is
	 * called.
	 *
	 * The adjusted_mode parameter is the mode output by the CRTC for the
	 * first bridge in the chain. It can be different from the mode
	 * parameter that contains the desired mode for the connector at the end
	 * of the bridges chain, for instance when the first bridge in the chain
	 * performs scaling. The adjusted mode is mostly useful for the first
	 * bridge in the chain and is likely irrelevant for the other bridges.
	 *
	 * For atomic drivers the adjusted_mode is the mode stored in
	 * &drm_crtc_state.adjusted_mode.
	 *
	 * NOTE:
	 *
	 * This is deprecated, do not use!
	 * New drivers shall set their mode in the
	 * &drm_bridge_funcs.atomic_enable operation.
	 */
	void (*mode_set)(struct drm_bridge *bridge,
			 const struct drm_display_mode *mode,
			 const struct drm_display_mode *adjusted_mode);
	/**
	 * @pre_enable:
	 *
	 * This callback should enable the bridge. It is called right before
	 * the preceding element in the display pipe is enabled. If the
	 * preceding element is a bridge this means it's called before that
	 * bridge's @pre_enable function. If the preceding element is a
	 * &drm_encoder it's called right before the encoder's
	 * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
	 * &drm_encoder_helper_funcs.dpms hook.
	 *
	 * The display pipe (i.e. clocks and timing signals) feeding this bridge
	 * will not yet be running when this callback is called. The bridge must
	 * not enable the display link feeding the next bridge in the chain (if
	 * there is one) when this callback is called.
	 *
	 * The @pre_enable callback is optional.
	 *
	 * NOTE:
	 *
	 * This is deprecated, do not use!
	 * New drivers shall use &drm_bridge_funcs.atomic_pre_enable.
	 */
	void (*pre_enable)(struct drm_bridge *bridge);

	/**
	 * @enable:
	 *
	 * This callback should enable the bridge. It is called right after
	 * the preceding element in the display pipe is enabled. If the
	 * preceding element is a bridge this means it's called after that
	 * bridge's @enable function. If the preceding element is a
	 * &drm_encoder it's called right after the encoder's
	 * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
	 * &drm_encoder_helper_funcs.dpms hook.
	 *
	 * The bridge can assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is running when this callback is called. This
	 * callback must enable the display link feeding the next bridge in the
	 * chain if there is one.
	 *
	 * The @enable callback is optional.
	 *
	 * NOTE:
	 *
	 * This is deprecated, do not use!
	 * New drivers shall use &drm_bridge_funcs.atomic_enable.
	 */
	void (*enable)(struct drm_bridge *bridge);

	/**
	 * @atomic_pre_enable:
	 *
	 * This callback should enable the bridge. It is called right before
	 * the preceding element in the display pipe is enabled. If the
	 * preceding element is a bridge this means it's called before that
	 * bridge's @atomic_pre_enable or @pre_enable function. If the preceding
	 * element is a &drm_encoder it's called right before the encoder's
	 * &drm_encoder_helper_funcs.atomic_enable hook.
	 *
	 * The display pipe (i.e. clocks and timing signals) feeding this bridge
	 * will not yet be running when this callback is called. The bridge must
	 * not enable the display link feeding the next bridge in the chain (if
	 * there is one) when this callback is called.
	 *
	 * The @atomic_pre_enable callback is optional.
	 */
	void (*atomic_pre_enable)(struct drm_bridge *bridge,
				  struct drm_bridge_state *old_bridge_state);

	/**
	 * @atomic_enable:
	 *
	 * This callback should enable the bridge. It is called right after
	 * the preceding element in the display pipe is enabled. If the
	 * preceding element is a bridge this means it's called after that
	 * bridge's @atomic_enable or @enable function. If the preceding element
	 * is a &drm_encoder it's called right after the encoder's
	 * &drm_encoder_helper_funcs.atomic_enable hook.
	 *
	 * The bridge can assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is running when this callback is called. This
	 * callback must enable the display link feeding the next bridge in the
	 * chain if there is one.
	 *
	 * The @atomic_enable callback is optional.
	 */
	void (*atomic_enable)(struct drm_bridge *bridge,
			      struct drm_bridge_state *old_bridge_state);
	/**
	 * @atomic_disable:
	 *
	 * This callback should disable the bridge. It is called right before
	 * the preceding element in the display pipe is disabled. If the
	 * preceding element is a bridge this means it's called before that
	 * bridge's @atomic_disable or @disable vfunc. If the preceding element
	 * is a &drm_encoder it's called right before the
	 * &drm_encoder_helper_funcs.atomic_disable hook.
	 *
	 * The bridge can assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is still running when this callback is called.
	 *
	 * The @atomic_disable callback is optional.
	 */
	void (*atomic_disable)(struct drm_bridge *bridge,
			       struct drm_bridge_state *old_bridge_state);

	/**
	 * @atomic_post_disable:
	 *
	 * This callback should disable the bridge. It is called right after the
	 * preceding element in the display pipe is disabled. If the preceding
	 * element is a bridge this means it's called after that bridge's
	 * @atomic_post_disable or @post_disable function. If the preceding
	 * element is a &drm_encoder it's called right after the encoder's
	 * &drm_encoder_helper_funcs.atomic_disable hook.
	 *
	 * The bridge must assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is no longer running when this callback is
	 * called.
	 *
	 * The @atomic_post_disable callback is optional.
	 */
	void (*atomic_post_disable)(struct drm_bridge *bridge,
				    struct drm_bridge_state *old_bridge_state);

	/**
	 * @atomic_duplicate_state:
	 *
	 * Duplicate the current bridge state object (which is guaranteed to be
	 * non-NULL).
	 *
	 * The atomic_duplicate_state hook is mandatory if the bridge
	 * implements any of the atomic hooks, and should be left unassigned
	 * otherwise. For bridges that don't subclass &drm_bridge_state, the
	 * drm_atomic_helper_bridge_duplicate_state() helper function shall be
	 * used to implement this hook.
	 *
	 * RETURNS:
	 * A valid drm_bridge_state object or NULL if the allocation fails.
	 */
	struct drm_bridge_state *(*atomic_duplicate_state)(struct drm_bridge *bridge);

	/**
	 * @atomic_destroy_state:
	 *
	 * Destroy a bridge state object previously allocated by
	 * &drm_bridge_funcs.atomic_duplicate_state().
	 *
	 * The atomic_destroy_state hook is mandatory if the bridge implements
	 * any of the atomic hooks, and should be left unassigned otherwise.
	 * For bridges that don't subclass &drm_bridge_state, the
	 * drm_atomic_helper_bridge_destroy_state() helper function shall be
	 * used to implement this hook.
	 */
	void (*atomic_destroy_state)(struct drm_bridge *bridge,
				     struct drm_bridge_state *state);

	/**
	 * @atomic_get_output_bus_fmts:
	 *
	 * Return the supported bus formats on the output end of a bridge.
	 * The returned array must be allocated with kmalloc() and will be
	 * freed by the caller. If the allocation fails, NULL should be
	 * returned. num_output_fmts must be set to the returned array size.
	 * Formats listed in the returned array should be listed in decreasing
	 * preference order (the core will try all formats until it finds one
	 * that works).
	 *
	 * This method is only called on the last element of the bridge chain
	 * as part of the bus format negotiation process that happens in
	 * &drm_atomic_bridge_chain_select_bus_fmts().
	 * This method is optional. When not implemented, the core will
	 * fall back to &drm_connector.display_info.bus_formats[0] if
	 * &drm_connector.display_info.num_bus_formats > 0,
	 * or to MEDIA_BUS_FMT_FIXED otherwise.
	 */
	u32 *(*atomic_get_output_bus_fmts)(struct drm_bridge *bridge,
					   struct drm_bridge_state *bridge_state,
					   struct drm_crtc_state *crtc_state,
					   struct drm_connector_state *conn_state,
					   unsigned int *num_output_fmts);

	/**
	 * @atomic_get_input_bus_fmts:
	 *
	 * Return the supported bus formats on the input end of a bridge for
	 * a specific output bus format.
	 *
	 * The returned array must be allocated with kmalloc() and will be
	 * freed by the caller. If the allocation fails, NULL should be
	 * returned. num_input_fmts must be set to the returned array size.
	 * Formats listed in the returned array should be listed in decreasing
	 * preference order (the core will try all formats until it finds one
	 * that works). When the format is not supported NULL should be
	 * returned and num_input_fmts should be set to 0.
	 *
	 * This method is called on all elements of the bridge chain as part of
	 * the bus format negotiation process that happens in
	 * drm_atomic_bridge_chain_select_bus_fmts().
	 * This method is optional. When not implemented, the core will bypass
	 * bus format negotiation on this element of the bridge without
	 * failing, and the previous element in the chain will be passed
	 * MEDIA_BUS_FMT_FIXED as its output bus format.
	 *
	 * Bridge drivers that need to support being linked to bridges that are
	 * not supporting bus format negotiation should handle the
	 * output_fmt == MEDIA_BUS_FMT_FIXED case appropriately, by selecting a
	 * sensible default value or extracting this information from somewhere
	 * else (FW property, &drm_display_mode, &drm_display_info, ...)
	 *
	 * Note: Even if input format selection on the first bridge has no
	 * impact on the negotiation process (bus format negotiation stops once
	 * we reach the first element of the chain), drivers are expected to
	 * return accurate input formats as the input format may be used to
	 * configure the CRTC output appropriately.
	 */
	u32 *(*atomic_get_input_bus_fmts)(struct drm_bridge *bridge,
					  struct drm_bridge_state *bridge_state,
					  struct drm_crtc_state *crtc_state,
					  struct drm_connector_state *conn_state,
					  u32 output_fmt,
					  unsigned int *num_input_fmts);

	/**
	 * @atomic_check:
	 *
	 * This method is responsible for checking bridge state correctness.
	 * It can also check the state of the surrounding components in chain
	 * to make sure the whole pipeline can work properly.
	 *
	 * &drm_bridge_funcs.atomic_check() hooks are called in reverse
	 * order (from the last to the first bridge).
	 *
	 * This method is optional. &drm_bridge_funcs.mode_fixup() is not
	 * called when &drm_bridge_funcs.atomic_check() is implemented, so only
	 * one of them should be provided.
	 *
	 * If drivers need to tweak &drm_bridge_state.input_bus_cfg.flags or
	 * &drm_bridge_state.output_bus_cfg.flags it should happen in
	 * this function. By default the &drm_bridge_state.output_bus_cfg.flags
	 * field is set to the next bridge
	 * &drm_bridge_state.input_bus_cfg.flags value or
	 * &drm_connector.display_info.bus_flags if the bridge is the last
	 * element in the chain.
	 *
	 * RETURNS:
	 * zero if the check passed, a negative error code otherwise.
	 */
	int (*atomic_check)(struct drm_bridge *bridge,
			    struct drm_bridge_state *bridge_state,
			    struct drm_crtc_state *crtc_state,
			    struct drm_connector_state *conn_state);

	/**
	 * @atomic_reset:
	 *
	 * Reset the bridge to a predefined state (or retrieve its current
	 * state) and return a &drm_bridge_state object matching this state.
	 * This function is called at attach time.
	 *
	 * The atomic_reset hook is mandatory if the bridge implements any of
	 * the atomic hooks, and should be left unassigned otherwise. For
	 * bridges that don't subclass &drm_bridge_state, the
	 * drm_atomic_helper_bridge_reset() helper function shall be used to
	 * implement this hook.
	 *
	 * Note that the atomic_reset() semantics is not exactly matching the
	 * reset() semantics found on other components (connector, plane, ...).
	 *
	 * 1. The reset operation happens when the bridge is attached, not when
	 *    drm_mode_config_reset() is called
	 * 2. It's meant to be used exclusively on bridges that have been
	 *    converted to the ATOMIC API
	 *
	 * RETURNS:
	 * A valid drm_bridge_state object in case of success, an ERR_PTR()
	 * giving the reason of the failure otherwise.
	 */
	struct drm_bridge_state *(*atomic_reset)(struct drm_bridge *bridge);

	/**
	 * @detect:
	 *
	 * Check if anything is attached to the bridge output.
	 *
	 * This callback is optional, if not implemented the bridge will be
	 * considered as always having a component attached to its output.
	 * Bridges that implement this callback shall set the
	 * DRM_BRIDGE_OP_DETECT flag in their &drm_bridge->ops.
	 *
	 * RETURNS:
	 *
	 * drm_connector_status indicating the bridge output status.
	 */
	enum drm_connector_status (*detect)(struct drm_bridge *bridge);

	/**
	 * @get_modes:
	 *
	 * Fill all modes currently valid for the sink into the &drm_connector
	 * with drm_mode_probed_add().
	 *
	 * The @get_modes callback is mostly intended to support non-probeable
	 * displays such as many fixed panels. Bridges that support reading
	 * EDID shall leave @get_modes unimplemented and implement the
	 * &drm_bridge_funcs->edid_read callback instead.
	 *
	 * This callback is optional. Bridges that implement it shall set the
	 * DRM_BRIDGE_OP_MODES flag in their &drm_bridge->ops.
	 *
	 * The connector parameter shall be used for the sole purpose of
	 * filling modes, and shall not be stored internally by bridge drivers
	 * for future usage.
	 *
	 * RETURNS:
	 *
	 * The number of modes added by calling drm_mode_probed_add().
	 */
	int (*get_modes)(struct drm_bridge *bridge,
			 struct drm_connector *connector);

	/**
	 * @edid_read:
	 *
	 * Read the EDID data of the connected display.
	 *
	 * The @edid_read callback is the preferred way of reporting mode
	 * information for a display connected to the bridge output. Bridges
	 * that support reading EDID shall implement this callback and leave
	 * the @get_modes callback unimplemented.
	 *
	 * The caller of this operation shall first verify the output
	 * connection status and refrain from reading EDID from a disconnected
	 * output.
	 *
	 * This callback is optional. Bridges that implement it shall set the
	 * DRM_BRIDGE_OP_EDID flag in their &drm_bridge->ops.
	 *
	 * The connector parameter shall be used for the sole purpose of EDID
	 * retrieval, and shall not be stored internally by bridge drivers for
	 * future usage.
	 *
	 * RETURNS:
	 *
	 * An edid structure newly allocated with drm_edid_alloc() or returned
	 * from drm_edid_read() family of functions on success, or NULL
	 * otherwise. The caller is responsible for freeing the returned edid
	 * structure with drm_edid_free().
	 */
	const struct drm_edid *(*edid_read)(struct drm_bridge *bridge,
					    struct drm_connector *connector);

	/**
	 * @hpd_notify:
	 *
	 * Notify the bridge of hot plug detection.
	 *
	 * This callback is optional, it may be implemented by bridges that
	 * need to be notified of display connection or disconnection for
	 * internal reasons. One use case is to reset the internal state of CEC
	 * controllers for HDMI bridges.
	 */
	void (*hpd_notify)(struct drm_bridge *bridge,
			   enum drm_connector_status status);

	/**
	 * @hpd_enable:
	 *
	 * Enable hot plug detection. From now on the bridge shall call
	 * drm_bridge_hpd_notify() each time a change is detected in the output
	 * connection status, until hot plug detection gets disabled with
	 * @hpd_disable.
	 *
	 * This callback is optional and shall only be implemented by bridges
	 * that support hot-plug notification without polling. Bridges that
	 * implement it shall also implement the @hpd_disable callback and set
	 * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops.
	 */
	void (*hpd_enable)(struct drm_bridge *bridge);

	/**
	 * @hpd_disable:
	 *
	 * Disable hot plug detection. Once this function returns the bridge
	 * shall not call drm_bridge_hpd_notify() when a change in the output
	 * connection status occurs.
	 *
	 * This callback is optional and shall only be implemented by bridges
	 * that support hot-plug notification without polling. Bridges that
	 * implement it shall also implement the @hpd_enable callback and set
	 * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops.
	 */
	void (*hpd_disable)(struct drm_bridge *bridge);

	/**
	 * @debugfs_init:
	 *
	 * Allows bridges to create bridge-specific debugfs files.
	 */
	void (*debugfs_init)(struct drm_bridge *bridge, struct dentry *root);
};

/**
 * struct drm_bridge_timings - timing information for the bridge
 */
struct drm_bridge_timings {
	/**
	 * @input_bus_flags:
	 *
	 * Tells what additional settings for the pixel data on the bus
	 * this bridge requires (like pixel signal polarity). See also
	 * &drm_display_info->bus_flags.
	 */
	u32 input_bus_flags;
	/**
	 * @setup_time_ps:
	 *
	 * Defines the time in picoseconds the input data lines must be
	 * stable before the clock edge.
	 */
	u32 setup_time_ps;
	/**
	 * @hold_time_ps:
	 *
	 * Defines the time in picoseconds taken for the bridge to sample the
	 * input signal after the clock edge.
	 */
	u32 hold_time_ps;
	/**
	 * @dual_link:
	 *
	 * True if the bus operates in dual-link mode. The exact meaning is
	 * dependent on the bus type. For LVDS buses, this indicates that even-
	 * and odd-numbered pixels are received on separate links.
	 */
	bool dual_link;
};

/**
 * enum drm_bridge_ops - Bitmask of operations supported by the bridge
 */
enum drm_bridge_ops {
	/**
	 * @DRM_BRIDGE_OP_DETECT: The bridge can detect displays connected to
	 * its output. Bridges that set this flag shall implement the
	 * &drm_bridge_funcs->detect callback.
	 */
	DRM_BRIDGE_OP_DETECT = BIT(0),
	/**
	 * @DRM_BRIDGE_OP_EDID: The bridge can retrieve the EDID of the display
	 * connected to its output. Bridges that set this flag shall implement
	 * the &drm_bridge_funcs->edid_read callback.
	 */
	DRM_BRIDGE_OP_EDID = BIT(1),
	/**
	 * @DRM_BRIDGE_OP_HPD: The bridge can detect hot-plug and hot-unplug
	 * without requiring polling. Bridges that set this flag shall
	 * implement the &drm_bridge_funcs->hpd_enable and
	 * &drm_bridge_funcs->hpd_disable callbacks if they support enabling
	 * and disabling hot-plug detection dynamically.
	 */
	DRM_BRIDGE_OP_HPD = BIT(2),
	/**
	 * @DRM_BRIDGE_OP_MODES: The bridge can retrieve the modes supported
	 * by the display at its output. This does not include reading EDID
	 * which is separately covered by @DRM_BRIDGE_OP_EDID. Bridges that set
	 * this flag shall implement the &drm_bridge_funcs->get_modes callback.
	 */
	DRM_BRIDGE_OP_MODES = BIT(3),
};

/**
 * struct drm_bridge - central DRM bridge control structure
 */
struct drm_bridge {
	/** @base: inherit from &drm_private_object */
	struct drm_private_obj base;
	/** @dev: DRM device this bridge belongs to */
	struct drm_device *dev;
	/** @encoder: encoder to which this bridge is connected */
	struct drm_encoder *encoder;
	/** @chain_node: used to form a bridge chain */
	struct list_head chain_node;
	/** @of_node: device node pointer to the bridge */
	struct device_node *of_node;
	/** @list: to keep track of all added bridges */
	struct list_head list;
	/**
	 * @timings:
	 *
	 * the timing specification for the bridge, if any (may be NULL)
	 */
	const struct drm_bridge_timings *timings;
	/** @funcs: control functions */
	const struct drm_bridge_funcs *funcs;
	/** @driver_private: pointer to the bridge driver's internal context */
	void *driver_private;
	/** @ops: bitmask of operations supported by the bridge */
	enum drm_bridge_ops ops;
	/**
	 * @type: Type of the connection at the bridge output
	 * (DRM_MODE_CONNECTOR_*). For bridges at the end of this chain this
	 * identifies the type of connected display.
	 */
	int type;
	/**
	 * @interlace_allowed: Indicate that the bridge can handle interlaced
	 * modes.
	 */
	bool interlace_allowed;
	/**
	 * @pre_enable_prev_first: The bridge requires that the prev
	 * bridge @pre_enable function is called before its @pre_enable,
	 * and conversely for post_disable. This is most frequently a
	 * requirement for DSI devices which need the host to be initialised
	 * before the peripheral.
	 */
	bool pre_enable_prev_first;
	/**
	 * @ddc: Associated I2C adapter for DDC access, if any.
	 */
	struct i2c_adapter *ddc;
	/** private: */
	/**
	 * @hpd_mutex: Protects the @hpd_cb and @hpd_data fields.
	 */
	struct mutex hpd_mutex;
	/**
	 * @hpd_cb: Hot plug detection callback, registered with
	 * drm_bridge_hpd_enable().
	 */
	void (*hpd_cb)(void *data, enum drm_connector_status status);
	/**
	 * @hpd_data: Private data passed to the Hot plug detection callback
	 * @hpd_cb.
	 */
	void *hpd_data;
};

static inline struct drm_bridge *
drm_priv_to_bridge(struct drm_private_obj *priv)
{
	return container_of(priv, struct drm_bridge, base);
}

void drm_bridge_add(struct drm_bridge *bridge);
int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge);
void drm_bridge_remove(struct drm_bridge *bridge);
int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
		      struct drm_bridge *previous,
		      enum drm_bridge_attach_flags flags);

#ifdef CONFIG_OF
struct drm_bridge *of_drm_find_bridge(struct device_node *np);
#else
static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np)
{
	return NULL;
}
#endif

/**
 * drm_bridge_get_next_bridge() - Get the next bridge in the chain
 * @bridge: bridge object
 *
 * RETURNS:
 * the next bridge in the chain after @bridge, or NULL if @bridge is the last.
 */
static inline struct drm_bridge *
drm_bridge_get_next_bridge(struct drm_bridge *bridge)
{
	if (list_is_last(&bridge->chain_node, &bridge->encoder->bridge_chain))
		return NULL;

	return list_next_entry(bridge, chain_node);
}

/**
 * drm_bridge_get_prev_bridge() - Get the previous bridge in the chain
 * @bridge: bridge object
 *
 * RETURNS:
 * the previous bridge in the chain, or NULL if @bridge is the first.
 */
static inline struct drm_bridge *
drm_bridge_get_prev_bridge(struct drm_bridge *bridge)
{
	if (list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain))
		return NULL;

	return list_prev_entry(bridge, chain_node);
}

/**
 * drm_bridge_chain_get_first_bridge() - Get the first bridge in the chain
 * @encoder: encoder object
 *
 * RETURNS:
 * the first bridge in the chain, or NULL if @encoder has no bridge attached
 * to it.
 */
static inline struct drm_bridge *
drm_bridge_chain_get_first_bridge(struct drm_encoder *encoder)
{
	return list_first_entry_or_null(&encoder->bridge_chain,
					struct drm_bridge, chain_node);
}

/**
 * drm_for_each_bridge_in_chain() - Iterate over all bridges present in a chain
 * @encoder: the encoder to iterate bridges on
 * @bridge: a bridge pointer updated to point to the current bridge at each
 *	    iteration
 *
 * Iterate over all bridges present in the bridge chain attached to @encoder.
 */
#define drm_for_each_bridge_in_chain(encoder, bridge)			\
	list_for_each_entry(bridge, &(encoder)->bridge_chain, chain_node)

bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
				 const struct drm_display_mode *mode,
				 struct drm_display_mode *adjusted_mode);
enum drm_mode_status
drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
			    const struct drm_display_info *info,
			    const struct drm_display_mode *mode);
void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
			       const struct drm_display_mode *mode,
			       const struct drm_display_mode *adjusted_mode);

int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
				  struct drm_crtc_state *crtc_state,
				  struct drm_connector_state *conn_state);
void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
				     struct drm_atomic_state *state);
void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
					  struct drm_atomic_state *state);
void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
					struct drm_atomic_state *state);
void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
				    struct drm_atomic_state *state);

u32 *
drm_atomic_helper_bridge_propagate_bus_fmt(struct drm_bridge *bridge,
					struct drm_bridge_state *bridge_state,
					struct drm_crtc_state *crtc_state,
					struct drm_connector_state *conn_state,
					u32 output_fmt,
					unsigned int *num_input_fmts);

enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge);
int drm_bridge_get_modes(struct drm_bridge *bridge,
			 struct drm_connector *connector);
const struct drm_edid *drm_bridge_edid_read(struct drm_bridge *bridge,
					    struct drm_connector *connector);
void drm_bridge_hpd_enable(struct drm_bridge *bridge,
			   void (*cb)(void *data,
				      enum drm_connector_status status),
			   void *data);
void drm_bridge_hpd_disable(struct drm_bridge *bridge);
void drm_bridge_hpd_notify(struct drm_bridge *bridge,
			   enum drm_connector_status status);

#ifdef CONFIG_DRM_PANEL_BRIDGE
bool drm_bridge_is_panel(const struct drm_bridge *bridge);
struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel);
struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel,
					      u32 connector_type);
void drm_panel_bridge_remove(struct drm_bridge *bridge);
int drm_panel_bridge_set_orientation(struct drm_connector *connector,
				     struct drm_bridge *bridge);
struct drm_bridge *devm_drm_panel_bridge_add(struct device *dev,
					     struct drm_panel *panel);
struct drm_bridge *devm_drm_panel_bridge_add_typed(struct device *dev,
						   struct drm_panel *panel,
						   u32 connector_type);
struct drm_bridge *drmm_panel_bridge_add(struct drm_device *drm,
					     struct drm_panel *panel);
struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge);
#else
static inline bool drm_bridge_is_panel(const struct drm_bridge *bridge)
{
	return false;
}

static inline int drm_panel_bridge_set_orientation(struct drm_connector *connector,
						   struct drm_bridge *bridge)
{
	return -EINVAL;
}
#endif

#if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL_BRIDGE)
struct drm_bridge *devm_drm_of_get_bridge(struct device *dev, struct device_node *node,
					  u32 port, u32 endpoint);
struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm, struct device_node *node,
					  u32 port, u32 endpoint);
#else
static inline struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
							struct device_node *node,
							u32 port,
							u32 endpoint)
{
	return ERR_PTR(-ENODEV);
}

static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
						     struct device_node *node,
						     u32 port,
						     u32 endpoint)
{
	return ERR_PTR(-ENODEV);
}
#endif

#endif