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1/*
2 * Copyright (c) 2014 Samsung Electronics Co., Ltd
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, sub license,
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 (including the
12 * next paragraph) shall be included in all copies or substantial portions
13 * of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24#include <linux/err.h>
25#include <linux/module.h>
26#include <linux/mutex.h>
27
28#include <drm/drm_atomic_state_helper.h>
29#include <drm/drm_bridge.h>
30#include <drm/drm_encoder.h>
31
32#include "drm_crtc_internal.h"
33
34/**
35 * DOC: overview
36 *
37 * &struct drm_bridge represents a device that hangs on to an encoder. These are
38 * handy when a regular &drm_encoder entity isn't enough to represent the entire
39 * encoder chain.
40 *
41 * A bridge is always attached to a single &drm_encoder at a time, but can be
42 * either connected to it directly, or through a chain of bridges::
43 *
44 * [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
45 *
46 * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
47 * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
48 * Chaining multiple bridges to the output of a bridge, or the same bridge to
49 * the output of different bridges, is not supported.
50 *
51 * Display drivers are responsible for linking encoders with the first bridge
52 * in the chains. This is done by acquiring the appropriate bridge with
53 * of_drm_find_bridge() or drm_of_find_panel_or_bridge(), or creating it for a
54 * panel with drm_panel_bridge_add_typed() (or the managed version
55 * devm_drm_panel_bridge_add_typed()). Once acquired, the bridge shall be
56 * attached to the encoder with a call to drm_bridge_attach().
57 *
58 * Bridges are responsible for linking themselves with the next bridge in the
59 * chain, if any. This is done the same way as for encoders, with the call to
60 * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
61 *
62 * Once these links are created, the bridges can participate along with encoder
63 * functions to perform mode validation and fixup (through
64 * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
65 * setting (through drm_bridge_chain_mode_set()), enable (through
66 * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
67 * and disable (through drm_atomic_bridge_chain_disable() and
68 * drm_atomic_bridge_chain_post_disable()). Those functions call the
69 * corresponding operations provided in &drm_bridge_funcs in sequence for all
70 * bridges in the chain.
71 *
72 * For display drivers that use the atomic helpers
73 * drm_atomic_helper_check_modeset(),
74 * drm_atomic_helper_commit_modeset_enables() and
75 * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
76 * commit check and commit tail handlers, or through the higher-level
77 * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
78 * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
79 * requires no intervention from the driver. For other drivers, the relevant
80 * DRM bridge chain functions shall be called manually.
81 *
82 * Bridges also participate in implementing the &drm_connector at the end of
83 * the bridge chain. Display drivers may use the drm_bridge_connector_init()
84 * helper to create the &drm_connector, or implement it manually on top of the
85 * connector-related operations exposed by the bridge (see the overview
86 * documentation of bridge operations for more details).
87 *
88 * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
89 * CRTCs, encoders or connectors and hence are not visible to userspace. They
90 * just provide additional hooks to get the desired output at the end of the
91 * encoder chain.
92 */
93
94static DEFINE_MUTEX(bridge_lock);
95static LIST_HEAD(bridge_list);
96
97/**
98 * drm_bridge_add - add the given bridge to the global bridge list
99 *
100 * @bridge: bridge control structure
101 */
102void drm_bridge_add(struct drm_bridge *bridge)
103{
104 mutex_init(&bridge->hpd_mutex);
105
106 mutex_lock(&bridge_lock);
107 list_add_tail(&bridge->list, &bridge_list);
108 mutex_unlock(&bridge_lock);
109}
110EXPORT_SYMBOL(drm_bridge_add);
111
112/**
113 * drm_bridge_remove - remove the given bridge from the global bridge list
114 *
115 * @bridge: bridge control structure
116 */
117void drm_bridge_remove(struct drm_bridge *bridge)
118{
119 mutex_lock(&bridge_lock);
120 list_del_init(&bridge->list);
121 mutex_unlock(&bridge_lock);
122
123 mutex_destroy(&bridge->hpd_mutex);
124}
125EXPORT_SYMBOL(drm_bridge_remove);
126
127static struct drm_private_state *
128drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
129{
130 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
131 struct drm_bridge_state *state;
132
133 state = bridge->funcs->atomic_duplicate_state(bridge);
134 return state ? &state->base : NULL;
135}
136
137static void
138drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
139 struct drm_private_state *s)
140{
141 struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
142 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
143
144 bridge->funcs->atomic_destroy_state(bridge, state);
145}
146
147static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
148 .atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
149 .atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
150};
151
152/**
153 * drm_bridge_attach - attach the bridge to an encoder's chain
154 *
155 * @encoder: DRM encoder
156 * @bridge: bridge to attach
157 * @previous: previous bridge in the chain (optional)
158 * @flags: DRM_BRIDGE_ATTACH_* flags
159 *
160 * Called by a kms driver to link the bridge to an encoder's chain. The previous
161 * argument specifies the previous bridge in the chain. If NULL, the bridge is
162 * linked directly at the encoder's output. Otherwise it is linked at the
163 * previous bridge's output.
164 *
165 * If non-NULL the previous bridge must be already attached by a call to this
166 * function.
167 *
168 * Note that bridges attached to encoders are auto-detached during encoder
169 * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
170 * *not* be balanced with a drm_bridge_detach() in driver code.
171 *
172 * RETURNS:
173 * Zero on success, error code on failure
174 */
175int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
176 struct drm_bridge *previous,
177 enum drm_bridge_attach_flags flags)
178{
179 int ret;
180
181 if (!encoder || !bridge)
182 return -EINVAL;
183
184 if (previous && (!previous->dev || previous->encoder != encoder))
185 return -EINVAL;
186
187 if (bridge->dev)
188 return -EBUSY;
189
190 bridge->dev = encoder->dev;
191 bridge->encoder = encoder;
192
193 if (previous)
194 list_add(&bridge->chain_node, &previous->chain_node);
195 else
196 list_add(&bridge->chain_node, &encoder->bridge_chain);
197
198 if (bridge->funcs->attach) {
199 ret = bridge->funcs->attach(bridge, flags);
200 if (ret < 0)
201 goto err_reset_bridge;
202 }
203
204 if (bridge->funcs->atomic_reset) {
205 struct drm_bridge_state *state;
206
207 state = bridge->funcs->atomic_reset(bridge);
208 if (IS_ERR(state)) {
209 ret = PTR_ERR(state);
210 goto err_detach_bridge;
211 }
212
213 drm_atomic_private_obj_init(bridge->dev, &bridge->base,
214 &state->base,
215 &drm_bridge_priv_state_funcs);
216 }
217
218 return 0;
219
220err_detach_bridge:
221 if (bridge->funcs->detach)
222 bridge->funcs->detach(bridge);
223
224err_reset_bridge:
225 bridge->dev = NULL;
226 bridge->encoder = NULL;
227 list_del(&bridge->chain_node);
228 return ret;
229}
230EXPORT_SYMBOL(drm_bridge_attach);
231
232void drm_bridge_detach(struct drm_bridge *bridge)
233{
234 if (WARN_ON(!bridge))
235 return;
236
237 if (WARN_ON(!bridge->dev))
238 return;
239
240 if (bridge->funcs->atomic_reset)
241 drm_atomic_private_obj_fini(&bridge->base);
242
243 if (bridge->funcs->detach)
244 bridge->funcs->detach(bridge);
245
246 list_del(&bridge->chain_node);
247 bridge->dev = NULL;
248}
249
250/**
251 * DOC: bridge operations
252 *
253 * Bridge drivers expose operations through the &drm_bridge_funcs structure.
254 * The DRM internals (atomic and CRTC helpers) use the helpers defined in
255 * drm_bridge.c to call bridge operations. Those operations are divided in
256 * three big categories to support different parts of the bridge usage.
257 *
258 * - The encoder-related operations support control of the bridges in the
259 * chain, and are roughly counterparts to the &drm_encoder_helper_funcs
260 * operations. They are used by the legacy CRTC and the atomic modeset
261 * helpers to perform mode validation, fixup and setting, and enable and
262 * disable the bridge automatically.
263 *
264 * The enable and disable operations are split in
265 * &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
266 * &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
267 * finer-grained control.
268 *
269 * Bridge drivers may implement the legacy version of those operations, or
270 * the atomic version (prefixed with atomic\_), in which case they shall also
271 * implement the atomic state bookkeeping operations
272 * (&drm_bridge_funcs.atomic_duplicate_state,
273 * &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
274 * Mixing atomic and non-atomic versions of the operations is not supported.
275 *
276 * - The bus format negotiation operations
277 * &drm_bridge_funcs.atomic_get_output_bus_fmts and
278 * &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
279 * negotiate the formats transmitted between bridges in the chain when
280 * multiple formats are supported. Negotiation for formats is performed
281 * transparently for display drivers by the atomic modeset helpers. Only
282 * atomic versions of those operations exist, bridge drivers that need to
283 * implement them shall thus also implement the atomic version of the
284 * encoder-related operations. This feature is not supported by the legacy
285 * CRTC helpers.
286 *
287 * - The connector-related operations support implementing a &drm_connector
288 * based on a chain of bridges. DRM bridges traditionally create a
289 * &drm_connector for bridges meant to be used at the end of the chain. This
290 * puts additional burden on bridge drivers, especially for bridges that may
291 * be used in the middle of a chain or at the end of it. Furthermore, it
292 * requires all operations of the &drm_connector to be handled by a single
293 * bridge, which doesn't always match the hardware architecture.
294 *
295 * To simplify bridge drivers and make the connector implementation more
296 * flexible, a new model allows bridges to unconditionally skip creation of
297 * &drm_connector and instead expose &drm_bridge_funcs operations to support
298 * an externally-implemented &drm_connector. Those operations are
299 * &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
300 * &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
301 * &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
302 * implemented, display drivers shall create a &drm_connector instance for
303 * each chain of bridges, and implement those connector instances based on
304 * the bridge connector operations.
305 *
306 * Bridge drivers shall implement the connector-related operations for all
307 * the features that the bridge hardware support. For instance, if a bridge
308 * supports reading EDID, the &drm_bridge_funcs.get_edid shall be
309 * implemented. This however doesn't mean that the DDC lines are wired to the
310 * bridge on a particular platform, as they could also be connected to an I2C
311 * controller of the SoC. Support for the connector-related operations on the
312 * running platform is reported through the &drm_bridge.ops flags. Bridge
313 * drivers shall detect which operations they can support on the platform
314 * (usually this information is provided by ACPI or DT), and set the
315 * &drm_bridge.ops flags for all supported operations. A flag shall only be
316 * set if the corresponding &drm_bridge_funcs operation is implemented, but
317 * an implemented operation doesn't necessarily imply that the corresponding
318 * flag will be set. Display drivers shall use the &drm_bridge.ops flags to
319 * decide which bridge to delegate a connector operation to. This mechanism
320 * allows providing a single static const &drm_bridge_funcs instance in
321 * bridge drivers, improving security by storing function pointers in
322 * read-only memory.
323 *
324 * In order to ease transition, bridge drivers may support both the old and
325 * new models by making connector creation optional and implementing the
326 * connected-related bridge operations. Connector creation is then controlled
327 * by the flags argument to the drm_bridge_attach() function. Display drivers
328 * that support the new model and create connectors themselves shall set the
329 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
330 * connector creation. For intermediate bridges in the chain, the flag shall
331 * be passed to the drm_bridge_attach() call for the downstream bridge.
332 * Bridge drivers that implement the new model only shall return an error
333 * from their &drm_bridge_funcs.attach handler when the
334 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
335 * should use the new model, and convert the bridge drivers they use if
336 * needed, in order to gradually transition to the new model.
337 */
338
339/**
340 * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
341 * encoder chain
342 * @bridge: bridge control structure
343 * @mode: desired mode to be set for the bridge
344 * @adjusted_mode: updated mode that works for this bridge
345 *
346 * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
347 * encoder chain, starting from the first bridge to the last.
348 *
349 * Note: the bridge passed should be the one closest to the encoder
350 *
351 * RETURNS:
352 * true on success, false on failure
353 */
354bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
355 const struct drm_display_mode *mode,
356 struct drm_display_mode *adjusted_mode)
357{
358 struct drm_encoder *encoder;
359
360 if (!bridge)
361 return true;
362
363 encoder = bridge->encoder;
364 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
365 if (!bridge->funcs->mode_fixup)
366 continue;
367
368 if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
369 return false;
370 }
371
372 return true;
373}
374EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
375
376/**
377 * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
378 * encoder chain.
379 * @bridge: bridge control structure
380 * @info: display info against which the mode shall be validated
381 * @mode: desired mode to be validated
382 *
383 * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
384 * chain, starting from the first bridge to the last. If at least one bridge
385 * does not accept the mode the function returns the error code.
386 *
387 * Note: the bridge passed should be the one closest to the encoder.
388 *
389 * RETURNS:
390 * MODE_OK on success, drm_mode_status Enum error code on failure
391 */
392enum drm_mode_status
393drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
394 const struct drm_display_info *info,
395 const struct drm_display_mode *mode)
396{
397 struct drm_encoder *encoder;
398
399 if (!bridge)
400 return MODE_OK;
401
402 encoder = bridge->encoder;
403 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
404 enum drm_mode_status ret;
405
406 if (!bridge->funcs->mode_valid)
407 continue;
408
409 ret = bridge->funcs->mode_valid(bridge, info, mode);
410 if (ret != MODE_OK)
411 return ret;
412 }
413
414 return MODE_OK;
415}
416EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
417
418/**
419 * drm_bridge_chain_disable - disables all bridges in the encoder chain
420 * @bridge: bridge control structure
421 *
422 * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
423 * chain, starting from the last bridge to the first. These are called before
424 * calling the encoder's prepare op.
425 *
426 * Note: the bridge passed should be the one closest to the encoder
427 */
428void drm_bridge_chain_disable(struct drm_bridge *bridge)
429{
430 struct drm_encoder *encoder;
431 struct drm_bridge *iter;
432
433 if (!bridge)
434 return;
435
436 encoder = bridge->encoder;
437 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
438 if (iter->funcs->disable)
439 iter->funcs->disable(iter);
440
441 if (iter == bridge)
442 break;
443 }
444}
445EXPORT_SYMBOL(drm_bridge_chain_disable);
446
447/**
448 * drm_bridge_chain_post_disable - cleans up after disabling all bridges in the
449 * encoder chain
450 * @bridge: bridge control structure
451 *
452 * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
453 * encoder chain, starting from the first bridge to the last. These are called
454 * after completing the encoder's prepare op.
455 *
456 * Note: the bridge passed should be the one closest to the encoder
457 */
458void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
459{
460 struct drm_encoder *encoder;
461
462 if (!bridge)
463 return;
464
465 encoder = bridge->encoder;
466 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
467 if (bridge->funcs->post_disable)
468 bridge->funcs->post_disable(bridge);
469 }
470}
471EXPORT_SYMBOL(drm_bridge_chain_post_disable);
472
473/**
474 * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
475 * encoder chain
476 * @bridge: bridge control structure
477 * @mode: desired mode to be set for the encoder chain
478 * @adjusted_mode: updated mode that works for this encoder chain
479 *
480 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
481 * encoder chain, starting from the first bridge to the last.
482 *
483 * Note: the bridge passed should be the one closest to the encoder
484 */
485void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
486 const struct drm_display_mode *mode,
487 const struct drm_display_mode *adjusted_mode)
488{
489 struct drm_encoder *encoder;
490
491 if (!bridge)
492 return;
493
494 encoder = bridge->encoder;
495 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
496 if (bridge->funcs->mode_set)
497 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
498 }
499}
500EXPORT_SYMBOL(drm_bridge_chain_mode_set);
501
502/**
503 * drm_bridge_chain_pre_enable - prepares for enabling all bridges in the
504 * encoder chain
505 * @bridge: bridge control structure
506 *
507 * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
508 * chain, starting from the last bridge to the first. These are called
509 * before calling the encoder's commit op.
510 *
511 * Note: the bridge passed should be the one closest to the encoder
512 */
513void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
514{
515 struct drm_encoder *encoder;
516 struct drm_bridge *iter;
517
518 if (!bridge)
519 return;
520
521 encoder = bridge->encoder;
522 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
523 if (iter->funcs->pre_enable)
524 iter->funcs->pre_enable(iter);
525 }
526}
527EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
528
529/**
530 * drm_bridge_chain_enable - enables all bridges in the encoder chain
531 * @bridge: bridge control structure
532 *
533 * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
534 * chain, starting from the first bridge to the last. These are called
535 * after completing the encoder's commit op.
536 *
537 * Note that the bridge passed should be the one closest to the encoder
538 */
539void drm_bridge_chain_enable(struct drm_bridge *bridge)
540{
541 struct drm_encoder *encoder;
542
543 if (!bridge)
544 return;
545
546 encoder = bridge->encoder;
547 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
548 if (bridge->funcs->enable)
549 bridge->funcs->enable(bridge);
550 }
551}
552EXPORT_SYMBOL(drm_bridge_chain_enable);
553
554/**
555 * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
556 * @bridge: bridge control structure
557 * @old_state: old atomic state
558 *
559 * Calls &drm_bridge_funcs.atomic_disable (falls back on
560 * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
561 * starting from the last bridge to the first. These are called before calling
562 * &drm_encoder_helper_funcs.atomic_disable
563 *
564 * Note: the bridge passed should be the one closest to the encoder
565 */
566void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
567 struct drm_atomic_state *old_state)
568{
569 struct drm_encoder *encoder;
570 struct drm_bridge *iter;
571
572 if (!bridge)
573 return;
574
575 encoder = bridge->encoder;
576 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
577 if (iter->funcs->atomic_disable) {
578 struct drm_bridge_state *old_bridge_state;
579
580 old_bridge_state =
581 drm_atomic_get_old_bridge_state(old_state,
582 iter);
583 if (WARN_ON(!old_bridge_state))
584 return;
585
586 iter->funcs->atomic_disable(iter, old_bridge_state);
587 } else if (iter->funcs->disable) {
588 iter->funcs->disable(iter);
589 }
590
591 if (iter == bridge)
592 break;
593 }
594}
595EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
596
597/**
598 * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
599 * in the encoder chain
600 * @bridge: bridge control structure
601 * @old_state: old atomic state
602 *
603 * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
604 * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
605 * starting from the first bridge to the last. These are called after completing
606 * &drm_encoder_helper_funcs.atomic_disable
607 *
608 * Note: the bridge passed should be the one closest to the encoder
609 */
610void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
611 struct drm_atomic_state *old_state)
612{
613 struct drm_encoder *encoder;
614
615 if (!bridge)
616 return;
617
618 encoder = bridge->encoder;
619 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
620 if (bridge->funcs->atomic_post_disable) {
621 struct drm_bridge_state *old_bridge_state;
622
623 old_bridge_state =
624 drm_atomic_get_old_bridge_state(old_state,
625 bridge);
626 if (WARN_ON(!old_bridge_state))
627 return;
628
629 bridge->funcs->atomic_post_disable(bridge,
630 old_bridge_state);
631 } else if (bridge->funcs->post_disable) {
632 bridge->funcs->post_disable(bridge);
633 }
634 }
635}
636EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
637
638/**
639 * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
640 * the encoder chain
641 * @bridge: bridge control structure
642 * @old_state: old atomic state
643 *
644 * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
645 * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
646 * starting from the last bridge to the first. These are called before calling
647 * &drm_encoder_helper_funcs.atomic_enable
648 *
649 * Note: the bridge passed should be the one closest to the encoder
650 */
651void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
652 struct drm_atomic_state *old_state)
653{
654 struct drm_encoder *encoder;
655 struct drm_bridge *iter;
656
657 if (!bridge)
658 return;
659
660 encoder = bridge->encoder;
661 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
662 if (iter->funcs->atomic_pre_enable) {
663 struct drm_bridge_state *old_bridge_state;
664
665 old_bridge_state =
666 drm_atomic_get_old_bridge_state(old_state,
667 iter);
668 if (WARN_ON(!old_bridge_state))
669 return;
670
671 iter->funcs->atomic_pre_enable(iter, old_bridge_state);
672 } else if (iter->funcs->pre_enable) {
673 iter->funcs->pre_enable(iter);
674 }
675
676 if (iter == bridge)
677 break;
678 }
679}
680EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
681
682/**
683 * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
684 * @bridge: bridge control structure
685 * @old_state: old atomic state
686 *
687 * Calls &drm_bridge_funcs.atomic_enable (falls back on
688 * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
689 * starting from the first bridge to the last. These are called after completing
690 * &drm_encoder_helper_funcs.atomic_enable
691 *
692 * Note: the bridge passed should be the one closest to the encoder
693 */
694void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
695 struct drm_atomic_state *old_state)
696{
697 struct drm_encoder *encoder;
698
699 if (!bridge)
700 return;
701
702 encoder = bridge->encoder;
703 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
704 if (bridge->funcs->atomic_enable) {
705 struct drm_bridge_state *old_bridge_state;
706
707 old_bridge_state =
708 drm_atomic_get_old_bridge_state(old_state,
709 bridge);
710 if (WARN_ON(!old_bridge_state))
711 return;
712
713 bridge->funcs->atomic_enable(bridge, old_bridge_state);
714 } else if (bridge->funcs->enable) {
715 bridge->funcs->enable(bridge);
716 }
717 }
718}
719EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
720
721static int drm_atomic_bridge_check(struct drm_bridge *bridge,
722 struct drm_crtc_state *crtc_state,
723 struct drm_connector_state *conn_state)
724{
725 if (bridge->funcs->atomic_check) {
726 struct drm_bridge_state *bridge_state;
727 int ret;
728
729 bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
730 bridge);
731 if (WARN_ON(!bridge_state))
732 return -EINVAL;
733
734 ret = bridge->funcs->atomic_check(bridge, bridge_state,
735 crtc_state, conn_state);
736 if (ret)
737 return ret;
738 } else if (bridge->funcs->mode_fixup) {
739 if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
740 &crtc_state->adjusted_mode))
741 return -EINVAL;
742 }
743
744 return 0;
745}
746
747static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
748 struct drm_bridge *cur_bridge,
749 struct drm_crtc_state *crtc_state,
750 struct drm_connector_state *conn_state,
751 u32 out_bus_fmt)
752{
753 struct drm_bridge_state *cur_state;
754 unsigned int num_in_bus_fmts, i;
755 struct drm_bridge *prev_bridge;
756 u32 *in_bus_fmts;
757 int ret;
758
759 prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
760 cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
761 cur_bridge);
762
763 /*
764 * If bus format negotiation is not supported by this bridge, let's
765 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
766 * hope that it can handle this situation gracefully (by providing
767 * appropriate default values).
768 */
769 if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
770 if (cur_bridge != first_bridge) {
771 ret = select_bus_fmt_recursive(first_bridge,
772 prev_bridge, crtc_state,
773 conn_state,
774 MEDIA_BUS_FMT_FIXED);
775 if (ret)
776 return ret;
777 }
778
779 /*
780 * Driver does not implement the atomic state hooks, but that's
781 * fine, as long as it does not access the bridge state.
782 */
783 if (cur_state) {
784 cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
785 cur_state->output_bus_cfg.format = out_bus_fmt;
786 }
787
788 return 0;
789 }
790
791 /*
792 * If the driver implements ->atomic_get_input_bus_fmts() it
793 * should also implement the atomic state hooks.
794 */
795 if (WARN_ON(!cur_state))
796 return -EINVAL;
797
798 in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
799 cur_state,
800 crtc_state,
801 conn_state,
802 out_bus_fmt,
803 &num_in_bus_fmts);
804 if (!num_in_bus_fmts)
805 return -ENOTSUPP;
806 else if (!in_bus_fmts)
807 return -ENOMEM;
808
809 if (first_bridge == cur_bridge) {
810 cur_state->input_bus_cfg.format = in_bus_fmts[0];
811 cur_state->output_bus_cfg.format = out_bus_fmt;
812 kfree(in_bus_fmts);
813 return 0;
814 }
815
816 for (i = 0; i < num_in_bus_fmts; i++) {
817 ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
818 crtc_state, conn_state,
819 in_bus_fmts[i]);
820 if (ret != -ENOTSUPP)
821 break;
822 }
823
824 if (!ret) {
825 cur_state->input_bus_cfg.format = in_bus_fmts[i];
826 cur_state->output_bus_cfg.format = out_bus_fmt;
827 }
828
829 kfree(in_bus_fmts);
830 return ret;
831}
832
833/*
834 * This function is called by &drm_atomic_bridge_chain_check() just before
835 * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
836 * It performs bus format negotiation between bridge elements. The negotiation
837 * happens in reverse order, starting from the last element in the chain up to
838 * @bridge.
839 *
840 * Negotiation starts by retrieving supported output bus formats on the last
841 * bridge element and testing them one by one. The test is recursive, meaning
842 * that for each tested output format, the whole chain will be walked backward,
843 * and each element will have to choose an input bus format that can be
844 * transcoded to the requested output format. When a bridge element does not
845 * support transcoding into a specific output format -ENOTSUPP is returned and
846 * the next bridge element will have to try a different format. If none of the
847 * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
848 *
849 * This implementation is relying on
850 * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
851 * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
852 * input/output formats.
853 *
854 * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
855 * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
856 * tries a single format: &drm_connector.display_info.bus_formats[0] if
857 * available, MEDIA_BUS_FMT_FIXED otherwise.
858 *
859 * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
860 * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
861 * bridge element that lacks this hook and asks the previous element in the
862 * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
863 * to do in that case (fail if they want to enforce bus format negotiation, or
864 * provide a reasonable default if they need to support pipelines where not
865 * all elements support bus format negotiation).
866 */
867static int
868drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
869 struct drm_crtc_state *crtc_state,
870 struct drm_connector_state *conn_state)
871{
872 struct drm_connector *conn = conn_state->connector;
873 struct drm_encoder *encoder = bridge->encoder;
874 struct drm_bridge_state *last_bridge_state;
875 unsigned int i, num_out_bus_fmts;
876 struct drm_bridge *last_bridge;
877 u32 *out_bus_fmts;
878 int ret = 0;
879
880 last_bridge = list_last_entry(&encoder->bridge_chain,
881 struct drm_bridge, chain_node);
882 last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
883 last_bridge);
884
885 if (last_bridge->funcs->atomic_get_output_bus_fmts) {
886 const struct drm_bridge_funcs *funcs = last_bridge->funcs;
887
888 /*
889 * If the driver implements ->atomic_get_output_bus_fmts() it
890 * should also implement the atomic state hooks.
891 */
892 if (WARN_ON(!last_bridge_state))
893 return -EINVAL;
894
895 out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
896 last_bridge_state,
897 crtc_state,
898 conn_state,
899 &num_out_bus_fmts);
900 if (!num_out_bus_fmts)
901 return -ENOTSUPP;
902 else if (!out_bus_fmts)
903 return -ENOMEM;
904 } else {
905 num_out_bus_fmts = 1;
906 out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
907 if (!out_bus_fmts)
908 return -ENOMEM;
909
910 if (conn->display_info.num_bus_formats &&
911 conn->display_info.bus_formats)
912 out_bus_fmts[0] = conn->display_info.bus_formats[0];
913 else
914 out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
915 }
916
917 for (i = 0; i < num_out_bus_fmts; i++) {
918 ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
919 conn_state, out_bus_fmts[i]);
920 if (ret != -ENOTSUPP)
921 break;
922 }
923
924 kfree(out_bus_fmts);
925
926 return ret;
927}
928
929static void
930drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
931 struct drm_connector *conn,
932 struct drm_atomic_state *state)
933{
934 struct drm_bridge_state *bridge_state, *next_bridge_state;
935 struct drm_bridge *next_bridge;
936 u32 output_flags = 0;
937
938 bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
939
940 /* No bridge state attached to this bridge => nothing to propagate. */
941 if (!bridge_state)
942 return;
943
944 next_bridge = drm_bridge_get_next_bridge(bridge);
945
946 /*
947 * Let's try to apply the most common case here, that is, propagate
948 * display_info flags for the last bridge, and propagate the input
949 * flags of the next bridge element to the output end of the current
950 * bridge when the bridge is not the last one.
951 * There are exceptions to this rule, like when signal inversion is
952 * happening at the board level, but that's something drivers can deal
953 * with from their &drm_bridge_funcs.atomic_check() implementation by
954 * simply overriding the flags value we've set here.
955 */
956 if (!next_bridge) {
957 output_flags = conn->display_info.bus_flags;
958 } else {
959 next_bridge_state = drm_atomic_get_new_bridge_state(state,
960 next_bridge);
961 /*
962 * No bridge state attached to the next bridge, just leave the
963 * flags to 0.
964 */
965 if (next_bridge_state)
966 output_flags = next_bridge_state->input_bus_cfg.flags;
967 }
968
969 bridge_state->output_bus_cfg.flags = output_flags;
970
971 /*
972 * Propage the output flags to the input end of the bridge. Again, it's
973 * not necessarily what all bridges want, but that's what most of them
974 * do, and by doing that by default we avoid forcing drivers to
975 * duplicate the "dummy propagation" logic.
976 */
977 bridge_state->input_bus_cfg.flags = output_flags;
978}
979
980/**
981 * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
982 * @bridge: bridge control structure
983 * @crtc_state: new CRTC state
984 * @conn_state: new connector state
985 *
986 * First trigger a bus format negotiation before calling
987 * &drm_bridge_funcs.atomic_check() (falls back on
988 * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
989 * starting from the last bridge to the first. These are called before calling
990 * &drm_encoder_helper_funcs.atomic_check()
991 *
992 * RETURNS:
993 * 0 on success, a negative error code on failure
994 */
995int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
996 struct drm_crtc_state *crtc_state,
997 struct drm_connector_state *conn_state)
998{
999 struct drm_connector *conn = conn_state->connector;
1000 struct drm_encoder *encoder;
1001 struct drm_bridge *iter;
1002 int ret;
1003
1004 if (!bridge)
1005 return 0;
1006
1007 ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1008 conn_state);
1009 if (ret)
1010 return ret;
1011
1012 encoder = bridge->encoder;
1013 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1014 int ret;
1015
1016 /*
1017 * Bus flags are propagated by default. If a bridge needs to
1018 * tweak the input bus flags for any reason, it should happen
1019 * in its &drm_bridge_funcs.atomic_check() implementation such
1020 * that preceding bridges in the chain can propagate the new
1021 * bus flags.
1022 */
1023 drm_atomic_bridge_propagate_bus_flags(iter, conn,
1024 crtc_state->state);
1025
1026 ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1027 if (ret)
1028 return ret;
1029
1030 if (iter == bridge)
1031 break;
1032 }
1033
1034 return 0;
1035}
1036EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1037
1038/**
1039 * drm_bridge_detect - check if anything is attached to the bridge output
1040 * @bridge: bridge control structure
1041 *
1042 * If the bridge supports output detection, as reported by the
1043 * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1044 * bridge and return the connection status. Otherwise return
1045 * connector_status_unknown.
1046 *
1047 * RETURNS:
1048 * The detection status on success, or connector_status_unknown if the bridge
1049 * doesn't support output detection.
1050 */
1051enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1052{
1053 if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1054 return connector_status_unknown;
1055
1056 return bridge->funcs->detect(bridge);
1057}
1058EXPORT_SYMBOL_GPL(drm_bridge_detect);
1059
1060/**
1061 * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1062 * @connector
1063 * @bridge: bridge control structure
1064 * @connector: the connector to fill with modes
1065 *
1066 * If the bridge supports output modes retrieval, as reported by the
1067 * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1068 * fill the connector with all valid modes and return the number of modes
1069 * added. Otherwise return 0.
1070 *
1071 * RETURNS:
1072 * The number of modes added to the connector.
1073 */
1074int drm_bridge_get_modes(struct drm_bridge *bridge,
1075 struct drm_connector *connector)
1076{
1077 if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1078 return 0;
1079
1080 return bridge->funcs->get_modes(bridge, connector);
1081}
1082EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1083
1084/**
1085 * drm_bridge_get_edid - get the EDID data of the connected display
1086 * @bridge: bridge control structure
1087 * @connector: the connector to read EDID for
1088 *
1089 * If the bridge supports output EDID retrieval, as reported by the
1090 * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1091 * get the EDID and return it. Otherwise return NULL.
1092 *
1093 * RETURNS:
1094 * The retrieved EDID on success, or NULL otherwise.
1095 */
1096struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1097 struct drm_connector *connector)
1098{
1099 if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1100 return NULL;
1101
1102 return bridge->funcs->get_edid(bridge, connector);
1103}
1104EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1105
1106/**
1107 * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1108 * @bridge: bridge control structure
1109 * @cb: hot-plug detection callback
1110 * @data: data to be passed to the hot-plug detection callback
1111 *
1112 * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1113 * and @data as hot plug notification callback. From now on the @cb will be
1114 * called with @data when an output status change is detected by the bridge,
1115 * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1116 *
1117 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1118 * bridge->ops. This function shall not be called when the flag is not set.
1119 *
1120 * Only one hot plug detection callback can be registered at a time, it is an
1121 * error to call this function when hot plug detection is already enabled for
1122 * the bridge.
1123 */
1124void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1125 void (*cb)(void *data,
1126 enum drm_connector_status status),
1127 void *data)
1128{
1129 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1130 return;
1131
1132 mutex_lock(&bridge->hpd_mutex);
1133
1134 if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1135 goto unlock;
1136
1137 bridge->hpd_cb = cb;
1138 bridge->hpd_data = data;
1139
1140 if (bridge->funcs->hpd_enable)
1141 bridge->funcs->hpd_enable(bridge);
1142
1143unlock:
1144 mutex_unlock(&bridge->hpd_mutex);
1145}
1146EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1147
1148/**
1149 * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1150 * @bridge: bridge control structure
1151 *
1152 * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1153 * plug detection callback previously registered with drm_bridge_hpd_enable().
1154 * Once this function returns the callback will not be called by the bridge
1155 * when an output status change occurs.
1156 *
1157 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1158 * bridge->ops. This function shall not be called when the flag is not set.
1159 */
1160void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1161{
1162 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1163 return;
1164
1165 mutex_lock(&bridge->hpd_mutex);
1166 if (bridge->funcs->hpd_disable)
1167 bridge->funcs->hpd_disable(bridge);
1168
1169 bridge->hpd_cb = NULL;
1170 bridge->hpd_data = NULL;
1171 mutex_unlock(&bridge->hpd_mutex);
1172}
1173EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1174
1175/**
1176 * drm_bridge_hpd_notify - notify hot plug detection events
1177 * @bridge: bridge control structure
1178 * @status: output connection status
1179 *
1180 * Bridge drivers shall call this function to report hot plug events when they
1181 * detect a change in the output status, when hot plug detection has been
1182 * enabled by drm_bridge_hpd_enable().
1183 *
1184 * This function shall be called in a context that can sleep.
1185 */
1186void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1187 enum drm_connector_status status)
1188{
1189 mutex_lock(&bridge->hpd_mutex);
1190 if (bridge->hpd_cb)
1191 bridge->hpd_cb(bridge->hpd_data, status);
1192 mutex_unlock(&bridge->hpd_mutex);
1193}
1194EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1195
1196#ifdef CONFIG_OF
1197/**
1198 * of_drm_find_bridge - find the bridge corresponding to the device node in
1199 * the global bridge list
1200 *
1201 * @np: device node
1202 *
1203 * RETURNS:
1204 * drm_bridge control struct on success, NULL on failure
1205 */
1206struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1207{
1208 struct drm_bridge *bridge;
1209
1210 mutex_lock(&bridge_lock);
1211
1212 list_for_each_entry(bridge, &bridge_list, list) {
1213 if (bridge->of_node == np) {
1214 mutex_unlock(&bridge_lock);
1215 return bridge;
1216 }
1217 }
1218
1219 mutex_unlock(&bridge_lock);
1220 return NULL;
1221}
1222EXPORT_SYMBOL(of_drm_find_bridge);
1223#endif
1224
1225MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1226MODULE_DESCRIPTION("DRM bridge infrastructure");
1227MODULE_LICENSE("GPL and additional rights");