2 * Copyright (c) 2014 Samsung Electronics Co., Ltd
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
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9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the
12 * next paragraph) shall be included in all copies or substantial portions
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
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21 * DEALINGS IN THE SOFTWARE.
24 #include <linux/err.h>
25 #include <linux/module.h>
26 #include <linux/mutex.h>
28 #include <drm/drm_atomic_state_helper.h>
29 #include <drm/drm_bridge.h>
30 #include <drm/drm_encoder.h>
31 #include <drm/drm_of.h>
32 #include <drm/drm_print.h>
34 #include "drm_crtc_internal.h"
39 * &struct drm_bridge represents a device that hangs on to an encoder. These are
40 * handy when a regular &drm_encoder entity isn't enough to represent the entire
43 * A bridge is always attached to a single &drm_encoder at a time, but can be
44 * either connected to it directly, or through a chain of bridges::
46 * [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
48 * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
49 * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
50 * Chaining multiple bridges to the output of a bridge, or the same bridge to
51 * the output of different bridges, is not supported.
53 * Display drivers are responsible for linking encoders with the first bridge
54 * in the chains. This is done by acquiring the appropriate bridge with
55 * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
56 * encoder with a call to drm_bridge_attach().
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.
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.
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.
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).
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
94 static DEFINE_MUTEX(bridge_lock);
95 static LIST_HEAD(bridge_list);
98 * drm_bridge_add - add the given bridge to the global bridge list
100 * @bridge: bridge control structure
102 void drm_bridge_add(struct drm_bridge *bridge)
104 mutex_init(&bridge->hpd_mutex);
106 mutex_lock(&bridge_lock);
107 list_add_tail(&bridge->list, &bridge_list);
108 mutex_unlock(&bridge_lock);
110 EXPORT_SYMBOL(drm_bridge_add);
113 * drm_bridge_remove - remove the given bridge from the global bridge list
115 * @bridge: bridge control structure
117 void drm_bridge_remove(struct drm_bridge *bridge)
119 mutex_lock(&bridge_lock);
120 list_del_init(&bridge->list);
121 mutex_unlock(&bridge_lock);
123 mutex_destroy(&bridge->hpd_mutex);
125 EXPORT_SYMBOL(drm_bridge_remove);
127 static struct drm_private_state *
128 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
130 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
131 struct drm_bridge_state *state;
133 state = bridge->funcs->atomic_duplicate_state(bridge);
134 return state ? &state->base : NULL;
138 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
139 struct drm_private_state *s)
141 struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
142 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
144 bridge->funcs->atomic_destroy_state(bridge, state);
147 static 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,
153 * drm_bridge_attach - attach the bridge to an encoder's chain
155 * @encoder: DRM encoder
156 * @bridge: bridge to attach
157 * @previous: previous bridge in the chain (optional)
158 * @flags: DRM_BRIDGE_ATTACH_* flags
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.
165 * If non-NULL the previous bridge must be already attached by a call to this
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.
173 * Zero on success, error code on failure
175 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
176 struct drm_bridge *previous,
177 enum drm_bridge_attach_flags flags)
181 if (!encoder || !bridge)
184 if (previous && (!previous->dev || previous->encoder != encoder))
190 bridge->dev = encoder->dev;
191 bridge->encoder = encoder;
194 list_add(&bridge->chain_node, &previous->chain_node);
196 list_add(&bridge->chain_node, &encoder->bridge_chain);
198 if (bridge->funcs->attach) {
199 ret = bridge->funcs->attach(bridge, flags);
201 goto err_reset_bridge;
204 if (bridge->funcs->atomic_reset) {
205 struct drm_bridge_state *state;
207 state = bridge->funcs->atomic_reset(bridge);
209 ret = PTR_ERR(state);
210 goto err_detach_bridge;
213 drm_atomic_private_obj_init(bridge->dev, &bridge->base,
215 &drm_bridge_priv_state_funcs);
221 if (bridge->funcs->detach)
222 bridge->funcs->detach(bridge);
226 bridge->encoder = NULL;
227 list_del(&bridge->chain_node);
230 DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
231 bridge->of_node, encoder->name, ret);
233 DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
239 EXPORT_SYMBOL(drm_bridge_attach);
241 void drm_bridge_detach(struct drm_bridge *bridge)
243 if (WARN_ON(!bridge))
246 if (WARN_ON(!bridge->dev))
249 if (bridge->funcs->atomic_reset)
250 drm_atomic_private_obj_fini(&bridge->base);
252 if (bridge->funcs->detach)
253 bridge->funcs->detach(bridge);
255 list_del(&bridge->chain_node);
260 * DOC: bridge operations
262 * Bridge drivers expose operations through the &drm_bridge_funcs structure.
263 * The DRM internals (atomic and CRTC helpers) use the helpers defined in
264 * drm_bridge.c to call bridge operations. Those operations are divided in
265 * three big categories to support different parts of the bridge usage.
267 * - The encoder-related operations support control of the bridges in the
268 * chain, and are roughly counterparts to the &drm_encoder_helper_funcs
269 * operations. They are used by the legacy CRTC and the atomic modeset
270 * helpers to perform mode validation, fixup and setting, and enable and
271 * disable the bridge automatically.
273 * The enable and disable operations are split in
274 * &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
275 * &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
276 * finer-grained control.
278 * Bridge drivers may implement the legacy version of those operations, or
279 * the atomic version (prefixed with atomic\_), in which case they shall also
280 * implement the atomic state bookkeeping operations
281 * (&drm_bridge_funcs.atomic_duplicate_state,
282 * &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
283 * Mixing atomic and non-atomic versions of the operations is not supported.
285 * - The bus format negotiation operations
286 * &drm_bridge_funcs.atomic_get_output_bus_fmts and
287 * &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
288 * negotiate the formats transmitted between bridges in the chain when
289 * multiple formats are supported. Negotiation for formats is performed
290 * transparently for display drivers by the atomic modeset helpers. Only
291 * atomic versions of those operations exist, bridge drivers that need to
292 * implement them shall thus also implement the atomic version of the
293 * encoder-related operations. This feature is not supported by the legacy
296 * - The connector-related operations support implementing a &drm_connector
297 * based on a chain of bridges. DRM bridges traditionally create a
298 * &drm_connector for bridges meant to be used at the end of the chain. This
299 * puts additional burden on bridge drivers, especially for bridges that may
300 * be used in the middle of a chain or at the end of it. Furthermore, it
301 * requires all operations of the &drm_connector to be handled by a single
302 * bridge, which doesn't always match the hardware architecture.
304 * To simplify bridge drivers and make the connector implementation more
305 * flexible, a new model allows bridges to unconditionally skip creation of
306 * &drm_connector and instead expose &drm_bridge_funcs operations to support
307 * an externally-implemented &drm_connector. Those operations are
308 * &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
309 * &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
310 * &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
311 * implemented, display drivers shall create a &drm_connector instance for
312 * each chain of bridges, and implement those connector instances based on
313 * the bridge connector operations.
315 * Bridge drivers shall implement the connector-related operations for all
316 * the features that the bridge hardware support. For instance, if a bridge
317 * supports reading EDID, the &drm_bridge_funcs.get_edid shall be
318 * implemented. This however doesn't mean that the DDC lines are wired to the
319 * bridge on a particular platform, as they could also be connected to an I2C
320 * controller of the SoC. Support for the connector-related operations on the
321 * running platform is reported through the &drm_bridge.ops flags. Bridge
322 * drivers shall detect which operations they can support on the platform
323 * (usually this information is provided by ACPI or DT), and set the
324 * &drm_bridge.ops flags for all supported operations. A flag shall only be
325 * set if the corresponding &drm_bridge_funcs operation is implemented, but
326 * an implemented operation doesn't necessarily imply that the corresponding
327 * flag will be set. Display drivers shall use the &drm_bridge.ops flags to
328 * decide which bridge to delegate a connector operation to. This mechanism
329 * allows providing a single static const &drm_bridge_funcs instance in
330 * bridge drivers, improving security by storing function pointers in
333 * In order to ease transition, bridge drivers may support both the old and
334 * new models by making connector creation optional and implementing the
335 * connected-related bridge operations. Connector creation is then controlled
336 * by the flags argument to the drm_bridge_attach() function. Display drivers
337 * that support the new model and create connectors themselves shall set the
338 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
339 * connector creation. For intermediate bridges in the chain, the flag shall
340 * be passed to the drm_bridge_attach() call for the downstream bridge.
341 * Bridge drivers that implement the new model only shall return an error
342 * from their &drm_bridge_funcs.attach handler when the
343 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
344 * should use the new model, and convert the bridge drivers they use if
345 * needed, in order to gradually transition to the new model.
349 * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
351 * @bridge: bridge control structure
352 * @mode: desired mode to be set for the bridge
353 * @adjusted_mode: updated mode that works for this bridge
355 * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
356 * encoder chain, starting from the first bridge to the last.
358 * Note: the bridge passed should be the one closest to the encoder
361 * true on success, false on failure
363 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
364 const struct drm_display_mode *mode,
365 struct drm_display_mode *adjusted_mode)
367 struct drm_encoder *encoder;
372 encoder = bridge->encoder;
373 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
374 if (!bridge->funcs->mode_fixup)
377 if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
383 EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
386 * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
388 * @bridge: bridge control structure
389 * @info: display info against which the mode shall be validated
390 * @mode: desired mode to be validated
392 * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
393 * chain, starting from the first bridge to the last. If at least one bridge
394 * does not accept the mode the function returns the error code.
396 * Note: the bridge passed should be the one closest to the encoder.
399 * MODE_OK on success, drm_mode_status Enum error code on failure
402 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
403 const struct drm_display_info *info,
404 const struct drm_display_mode *mode)
406 struct drm_encoder *encoder;
411 encoder = bridge->encoder;
412 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
413 enum drm_mode_status ret;
415 if (!bridge->funcs->mode_valid)
418 ret = bridge->funcs->mode_valid(bridge, info, mode);
425 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
428 * drm_bridge_chain_disable - disables all bridges in the encoder chain
429 * @bridge: bridge control structure
431 * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
432 * chain, starting from the last bridge to the first. These are called before
433 * calling the encoder's prepare op.
435 * Note: the bridge passed should be the one closest to the encoder
437 void drm_bridge_chain_disable(struct drm_bridge *bridge)
439 struct drm_encoder *encoder;
440 struct drm_bridge *iter;
445 encoder = bridge->encoder;
446 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
447 if (iter->funcs->disable)
448 iter->funcs->disable(iter);
454 EXPORT_SYMBOL(drm_bridge_chain_disable);
457 * drm_bridge_chain_post_disable - cleans up after disabling all bridges in the
459 * @bridge: bridge control structure
461 * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
462 * encoder chain, starting from the first bridge to the last. These are called
463 * after completing the encoder's prepare op.
465 * Note: the bridge passed should be the one closest to the encoder
467 void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
469 struct drm_encoder *encoder;
474 encoder = bridge->encoder;
475 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
476 if (bridge->funcs->post_disable)
477 bridge->funcs->post_disable(bridge);
480 EXPORT_SYMBOL(drm_bridge_chain_post_disable);
483 * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
485 * @bridge: bridge control structure
486 * @mode: desired mode to be set for the encoder chain
487 * @adjusted_mode: updated mode that works for this encoder chain
489 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
490 * encoder chain, starting from the first bridge to the last.
492 * Note: the bridge passed should be the one closest to the encoder
494 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
495 const struct drm_display_mode *mode,
496 const struct drm_display_mode *adjusted_mode)
498 struct drm_encoder *encoder;
503 encoder = bridge->encoder;
504 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
505 if (bridge->funcs->mode_set)
506 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
509 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
512 * drm_bridge_chain_pre_enable - prepares for enabling all bridges in the
514 * @bridge: bridge control structure
516 * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
517 * chain, starting from the last bridge to the first. These are called
518 * before calling the encoder's commit op.
520 * Note: the bridge passed should be the one closest to the encoder
522 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
524 struct drm_encoder *encoder;
525 struct drm_bridge *iter;
530 encoder = bridge->encoder;
531 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
532 if (iter->funcs->pre_enable)
533 iter->funcs->pre_enable(iter);
539 EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
542 * drm_bridge_chain_enable - enables all bridges in the encoder chain
543 * @bridge: bridge control structure
545 * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
546 * chain, starting from the first bridge to the last. These are called
547 * after completing the encoder's commit op.
549 * Note that the bridge passed should be the one closest to the encoder
551 void drm_bridge_chain_enable(struct drm_bridge *bridge)
553 struct drm_encoder *encoder;
558 encoder = bridge->encoder;
559 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
560 if (bridge->funcs->enable)
561 bridge->funcs->enable(bridge);
564 EXPORT_SYMBOL(drm_bridge_chain_enable);
567 * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
568 * @bridge: bridge control structure
569 * @old_state: old atomic state
571 * Calls &drm_bridge_funcs.atomic_disable (falls back on
572 * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
573 * starting from the last bridge to the first. These are called before calling
574 * &drm_encoder_helper_funcs.atomic_disable
576 * Note: the bridge passed should be the one closest to the encoder
578 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
579 struct drm_atomic_state *old_state)
581 struct drm_encoder *encoder;
582 struct drm_bridge *iter;
587 encoder = bridge->encoder;
588 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
589 if (iter->funcs->atomic_disable) {
590 struct drm_bridge_state *old_bridge_state;
593 drm_atomic_get_old_bridge_state(old_state,
595 if (WARN_ON(!old_bridge_state))
598 iter->funcs->atomic_disable(iter, old_bridge_state);
599 } else if (iter->funcs->disable) {
600 iter->funcs->disable(iter);
607 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
610 * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
611 * in the encoder chain
612 * @bridge: bridge control structure
613 * @old_state: old atomic state
615 * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
616 * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
617 * starting from the first bridge to the last. These are called after completing
618 * &drm_encoder_helper_funcs.atomic_disable
620 * Note: the bridge passed should be the one closest to the encoder
622 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
623 struct drm_atomic_state *old_state)
625 struct drm_encoder *encoder;
630 encoder = bridge->encoder;
631 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
632 if (bridge->funcs->atomic_post_disable) {
633 struct drm_bridge_state *old_bridge_state;
636 drm_atomic_get_old_bridge_state(old_state,
638 if (WARN_ON(!old_bridge_state))
641 bridge->funcs->atomic_post_disable(bridge,
643 } else if (bridge->funcs->post_disable) {
644 bridge->funcs->post_disable(bridge);
648 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
651 * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
653 * @bridge: bridge control structure
654 * @old_state: old atomic state
656 * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
657 * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
658 * starting from the last bridge to the first. These are called before calling
659 * &drm_encoder_helper_funcs.atomic_enable
661 * Note: the bridge passed should be the one closest to the encoder
663 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
664 struct drm_atomic_state *old_state)
666 struct drm_encoder *encoder;
667 struct drm_bridge *iter;
672 encoder = bridge->encoder;
673 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
674 if (iter->funcs->atomic_pre_enable) {
675 struct drm_bridge_state *old_bridge_state;
678 drm_atomic_get_old_bridge_state(old_state,
680 if (WARN_ON(!old_bridge_state))
683 iter->funcs->atomic_pre_enable(iter, old_bridge_state);
684 } else if (iter->funcs->pre_enable) {
685 iter->funcs->pre_enable(iter);
692 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
695 * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
696 * @bridge: bridge control structure
697 * @old_state: old atomic state
699 * Calls &drm_bridge_funcs.atomic_enable (falls back on
700 * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
701 * starting from the first bridge to the last. These are called after completing
702 * &drm_encoder_helper_funcs.atomic_enable
704 * Note: the bridge passed should be the one closest to the encoder
706 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
707 struct drm_atomic_state *old_state)
709 struct drm_encoder *encoder;
714 encoder = bridge->encoder;
715 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
716 if (bridge->funcs->atomic_enable) {
717 struct drm_bridge_state *old_bridge_state;
720 drm_atomic_get_old_bridge_state(old_state,
722 if (WARN_ON(!old_bridge_state))
725 bridge->funcs->atomic_enable(bridge, old_bridge_state);
726 } else if (bridge->funcs->enable) {
727 bridge->funcs->enable(bridge);
731 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
733 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
734 struct drm_crtc_state *crtc_state,
735 struct drm_connector_state *conn_state)
737 if (bridge->funcs->atomic_check) {
738 struct drm_bridge_state *bridge_state;
741 bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
743 if (WARN_ON(!bridge_state))
746 ret = bridge->funcs->atomic_check(bridge, bridge_state,
747 crtc_state, conn_state);
750 } else if (bridge->funcs->mode_fixup) {
751 if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
752 &crtc_state->adjusted_mode))
759 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
760 struct drm_bridge *cur_bridge,
761 struct drm_crtc_state *crtc_state,
762 struct drm_connector_state *conn_state,
765 unsigned int i, num_in_bus_fmts = 0;
766 struct drm_bridge_state *cur_state;
767 struct drm_bridge *prev_bridge;
771 prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
772 cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
776 * If bus format negotiation is not supported by this bridge, let's
777 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
778 * hope that it can handle this situation gracefully (by providing
779 * appropriate default values).
781 if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
782 if (cur_bridge != first_bridge) {
783 ret = select_bus_fmt_recursive(first_bridge,
784 prev_bridge, crtc_state,
786 MEDIA_BUS_FMT_FIXED);
792 * Driver does not implement the atomic state hooks, but that's
793 * fine, as long as it does not access the bridge state.
796 cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
797 cur_state->output_bus_cfg.format = out_bus_fmt;
804 * If the driver implements ->atomic_get_input_bus_fmts() it
805 * should also implement the atomic state hooks.
807 if (WARN_ON(!cur_state))
810 in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
816 if (!num_in_bus_fmts)
818 else if (!in_bus_fmts)
821 if (first_bridge == cur_bridge) {
822 cur_state->input_bus_cfg.format = in_bus_fmts[0];
823 cur_state->output_bus_cfg.format = out_bus_fmt;
828 for (i = 0; i < num_in_bus_fmts; i++) {
829 ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
830 crtc_state, conn_state,
832 if (ret != -ENOTSUPP)
837 cur_state->input_bus_cfg.format = in_bus_fmts[i];
838 cur_state->output_bus_cfg.format = out_bus_fmt;
846 * This function is called by &drm_atomic_bridge_chain_check() just before
847 * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
848 * It performs bus format negotiation between bridge elements. The negotiation
849 * happens in reverse order, starting from the last element in the chain up to
852 * Negotiation starts by retrieving supported output bus formats on the last
853 * bridge element and testing them one by one. The test is recursive, meaning
854 * that for each tested output format, the whole chain will be walked backward,
855 * and each element will have to choose an input bus format that can be
856 * transcoded to the requested output format. When a bridge element does not
857 * support transcoding into a specific output format -ENOTSUPP is returned and
858 * the next bridge element will have to try a different format. If none of the
859 * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
861 * This implementation is relying on
862 * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
863 * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
864 * input/output formats.
866 * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
867 * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
868 * tries a single format: &drm_connector.display_info.bus_formats[0] if
869 * available, MEDIA_BUS_FMT_FIXED otherwise.
871 * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
872 * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
873 * bridge element that lacks this hook and asks the previous element in the
874 * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
875 * to do in that case (fail if they want to enforce bus format negotiation, or
876 * provide a reasonable default if they need to support pipelines where not
877 * all elements support bus format negotiation).
880 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
881 struct drm_crtc_state *crtc_state,
882 struct drm_connector_state *conn_state)
884 struct drm_connector *conn = conn_state->connector;
885 struct drm_encoder *encoder = bridge->encoder;
886 struct drm_bridge_state *last_bridge_state;
887 unsigned int i, num_out_bus_fmts = 0;
888 struct drm_bridge *last_bridge;
892 last_bridge = list_last_entry(&encoder->bridge_chain,
893 struct drm_bridge, chain_node);
894 last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
897 if (last_bridge->funcs->atomic_get_output_bus_fmts) {
898 const struct drm_bridge_funcs *funcs = last_bridge->funcs;
901 * If the driver implements ->atomic_get_output_bus_fmts() it
902 * should also implement the atomic state hooks.
904 if (WARN_ON(!last_bridge_state))
907 out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
912 if (!num_out_bus_fmts)
914 else if (!out_bus_fmts)
917 num_out_bus_fmts = 1;
918 out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
922 if (conn->display_info.num_bus_formats &&
923 conn->display_info.bus_formats)
924 out_bus_fmts[0] = conn->display_info.bus_formats[0];
926 out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
929 for (i = 0; i < num_out_bus_fmts; i++) {
930 ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
931 conn_state, out_bus_fmts[i]);
932 if (ret != -ENOTSUPP)
942 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
943 struct drm_connector *conn,
944 struct drm_atomic_state *state)
946 struct drm_bridge_state *bridge_state, *next_bridge_state;
947 struct drm_bridge *next_bridge;
948 u32 output_flags = 0;
950 bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
952 /* No bridge state attached to this bridge => nothing to propagate. */
956 next_bridge = drm_bridge_get_next_bridge(bridge);
959 * Let's try to apply the most common case here, that is, propagate
960 * display_info flags for the last bridge, and propagate the input
961 * flags of the next bridge element to the output end of the current
962 * bridge when the bridge is not the last one.
963 * There are exceptions to this rule, like when signal inversion is
964 * happening at the board level, but that's something drivers can deal
965 * with from their &drm_bridge_funcs.atomic_check() implementation by
966 * simply overriding the flags value we've set here.
969 output_flags = conn->display_info.bus_flags;
971 next_bridge_state = drm_atomic_get_new_bridge_state(state,
974 * No bridge state attached to the next bridge, just leave the
977 if (next_bridge_state)
978 output_flags = next_bridge_state->input_bus_cfg.flags;
981 bridge_state->output_bus_cfg.flags = output_flags;
984 * Propagate the output flags to the input end of the bridge. Again, it's
985 * not necessarily what all bridges want, but that's what most of them
986 * do, and by doing that by default we avoid forcing drivers to
987 * duplicate the "dummy propagation" logic.
989 bridge_state->input_bus_cfg.flags = output_flags;
993 * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
994 * @bridge: bridge control structure
995 * @crtc_state: new CRTC state
996 * @conn_state: new connector state
998 * First trigger a bus format negotiation before calling
999 * &drm_bridge_funcs.atomic_check() (falls back on
1000 * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1001 * starting from the last bridge to the first. These are called before calling
1002 * &drm_encoder_helper_funcs.atomic_check()
1005 * 0 on success, a negative error code on failure
1007 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1008 struct drm_crtc_state *crtc_state,
1009 struct drm_connector_state *conn_state)
1011 struct drm_connector *conn = conn_state->connector;
1012 struct drm_encoder *encoder;
1013 struct drm_bridge *iter;
1019 ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1024 encoder = bridge->encoder;
1025 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1029 * Bus flags are propagated by default. If a bridge needs to
1030 * tweak the input bus flags for any reason, it should happen
1031 * in its &drm_bridge_funcs.atomic_check() implementation such
1032 * that preceding bridges in the chain can propagate the new
1035 drm_atomic_bridge_propagate_bus_flags(iter, conn,
1038 ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1048 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1051 * drm_bridge_detect - check if anything is attached to the bridge output
1052 * @bridge: bridge control structure
1054 * If the bridge supports output detection, as reported by the
1055 * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1056 * bridge and return the connection status. Otherwise return
1057 * connector_status_unknown.
1060 * The detection status on success, or connector_status_unknown if the bridge
1061 * doesn't support output detection.
1063 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1065 if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1066 return connector_status_unknown;
1068 return bridge->funcs->detect(bridge);
1070 EXPORT_SYMBOL_GPL(drm_bridge_detect);
1073 * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1075 * @bridge: bridge control structure
1076 * @connector: the connector to fill with modes
1078 * If the bridge supports output modes retrieval, as reported by the
1079 * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1080 * fill the connector with all valid modes and return the number of modes
1081 * added. Otherwise return 0.
1084 * The number of modes added to the connector.
1086 int drm_bridge_get_modes(struct drm_bridge *bridge,
1087 struct drm_connector *connector)
1089 if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1092 return bridge->funcs->get_modes(bridge, connector);
1094 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1097 * drm_bridge_get_edid - get the EDID data of the connected display
1098 * @bridge: bridge control structure
1099 * @connector: the connector to read EDID for
1101 * If the bridge supports output EDID retrieval, as reported by the
1102 * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1103 * get the EDID and return it. Otherwise return NULL.
1106 * The retrieved EDID on success, or NULL otherwise.
1108 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1109 struct drm_connector *connector)
1111 if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1114 return bridge->funcs->get_edid(bridge, connector);
1116 EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1119 * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1120 * @bridge: bridge control structure
1121 * @cb: hot-plug detection callback
1122 * @data: data to be passed to the hot-plug detection callback
1124 * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1125 * and @data as hot plug notification callback. From now on the @cb will be
1126 * called with @data when an output status change is detected by the bridge,
1127 * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1129 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1130 * bridge->ops. This function shall not be called when the flag is not set.
1132 * Only one hot plug detection callback can be registered at a time, it is an
1133 * error to call this function when hot plug detection is already enabled for
1136 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1137 void (*cb)(void *data,
1138 enum drm_connector_status status),
1141 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1144 mutex_lock(&bridge->hpd_mutex);
1146 if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1149 bridge->hpd_cb = cb;
1150 bridge->hpd_data = data;
1152 if (bridge->funcs->hpd_enable)
1153 bridge->funcs->hpd_enable(bridge);
1156 mutex_unlock(&bridge->hpd_mutex);
1158 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1161 * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1162 * @bridge: bridge control structure
1164 * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1165 * plug detection callback previously registered with drm_bridge_hpd_enable().
1166 * Once this function returns the callback will not be called by the bridge
1167 * when an output status change occurs.
1169 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1170 * bridge->ops. This function shall not be called when the flag is not set.
1172 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1174 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1177 mutex_lock(&bridge->hpd_mutex);
1178 if (bridge->funcs->hpd_disable)
1179 bridge->funcs->hpd_disable(bridge);
1181 bridge->hpd_cb = NULL;
1182 bridge->hpd_data = NULL;
1183 mutex_unlock(&bridge->hpd_mutex);
1185 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1188 * drm_bridge_hpd_notify - notify hot plug detection events
1189 * @bridge: bridge control structure
1190 * @status: output connection status
1192 * Bridge drivers shall call this function to report hot plug events when they
1193 * detect a change in the output status, when hot plug detection has been
1194 * enabled by drm_bridge_hpd_enable().
1196 * This function shall be called in a context that can sleep.
1198 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1199 enum drm_connector_status status)
1201 mutex_lock(&bridge->hpd_mutex);
1203 bridge->hpd_cb(bridge->hpd_data, status);
1204 mutex_unlock(&bridge->hpd_mutex);
1206 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1210 * of_drm_find_bridge - find the bridge corresponding to the device node in
1211 * the global bridge list
1216 * drm_bridge control struct on success, NULL on failure
1218 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1220 struct drm_bridge *bridge;
1222 mutex_lock(&bridge_lock);
1224 list_for_each_entry(bridge, &bridge_list, list) {
1225 if (bridge->of_node == np) {
1226 mutex_unlock(&bridge_lock);
1231 mutex_unlock(&bridge_lock);
1234 EXPORT_SYMBOL(of_drm_find_bridge);
1237 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1238 MODULE_DESCRIPTION("DRM bridge infrastructure");
1239 MODULE_LICENSE("GPL and additional rights");