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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/media-bus-format.h>
26#include <linux/module.h>
27#include <linux/mutex.h>
28
29#include <drm/drm_atomic_state_helper.h>
30#include <drm/drm_bridge.h>
31#include <drm/drm_debugfs.h>
32#include <drm/drm_edid.h>
33#include <drm/drm_encoder.h>
34#include <drm/drm_file.h>
35#include <drm/drm_of.h>
36#include <drm/drm_print.h>
37
38#include "drm_crtc_internal.h"
39
40/**
41 * DOC: overview
42 *
43 * &struct drm_bridge represents a device that hangs on to an encoder. These are
44 * handy when a regular &drm_encoder entity isn't enough to represent the entire
45 * encoder chain.
46 *
47 * A bridge is always attached to a single &drm_encoder at a time, but can be
48 * either connected to it directly, or through a chain of bridges::
49 *
50 * [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
51 *
52 * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
53 * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
54 * Chaining multiple bridges to the output of a bridge, or the same bridge to
55 * the output of different bridges, is not supported.
56 *
57 * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
58 * CRTCs, encoders or connectors and hence are not visible to userspace. They
59 * just provide additional hooks to get the desired output at the end of the
60 * encoder chain.
61 */
62
63/**
64 * DOC: display driver integration
65 *
66 * Display drivers are responsible for linking encoders with the first bridge
67 * in the chains. This is done by acquiring the appropriate bridge with
68 * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
69 * encoder with a call to drm_bridge_attach().
70 *
71 * Bridges are responsible for linking themselves with the next bridge in the
72 * chain, if any. This is done the same way as for encoders, with the call to
73 * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
74 *
75 * Once these links are created, the bridges can participate along with encoder
76 * functions to perform mode validation and fixup (through
77 * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
78 * setting (through drm_bridge_chain_mode_set()), enable (through
79 * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
80 * and disable (through drm_atomic_bridge_chain_disable() and
81 * drm_atomic_bridge_chain_post_disable()). Those functions call the
82 * corresponding operations provided in &drm_bridge_funcs in sequence for all
83 * bridges in the chain.
84 *
85 * For display drivers that use the atomic helpers
86 * drm_atomic_helper_check_modeset(),
87 * drm_atomic_helper_commit_modeset_enables() and
88 * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
89 * commit check and commit tail handlers, or through the higher-level
90 * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
91 * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
92 * requires no intervention from the driver. For other drivers, the relevant
93 * DRM bridge chain functions shall be called manually.
94 *
95 * Bridges also participate in implementing the &drm_connector at the end of
96 * the bridge chain. Display drivers may use the drm_bridge_connector_init()
97 * helper to create the &drm_connector, or implement it manually on top of the
98 * connector-related operations exposed by the bridge (see the overview
99 * documentation of bridge operations for more details).
100 */
101
102/**
103 * DOC: special care dsi
104 *
105 * The interaction between the bridges and other frameworks involved in
106 * the probing of the upstream driver and the bridge driver can be
107 * challenging. Indeed, there's multiple cases that needs to be
108 * considered:
109 *
110 * - The upstream driver doesn't use the component framework and isn't a
111 * MIPI-DSI host. In this case, the bridge driver will probe at some
112 * point and the upstream driver should try to probe again by returning
113 * EPROBE_DEFER as long as the bridge driver hasn't probed.
114 *
115 * - The upstream driver doesn't use the component framework, but is a
116 * MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
117 * controlled. In this case, the bridge device is a child of the
118 * display device and when it will probe it's assured that the display
119 * device (and MIPI-DSI host) is present. The upstream driver will be
120 * assured that the bridge driver is connected between the
121 * &mipi_dsi_host_ops.attach and &mipi_dsi_host_ops.detach operations.
122 * Therefore, it must run mipi_dsi_host_register() in its probe
123 * function, and then run drm_bridge_attach() in its
124 * &mipi_dsi_host_ops.attach hook.
125 *
126 * - The upstream driver uses the component framework and is a MIPI-DSI
127 * host. The bridge device uses the MIPI-DCS commands to be
128 * controlled. This is the same situation than above, and can run
129 * mipi_dsi_host_register() in either its probe or bind hooks.
130 *
131 * - The upstream driver uses the component framework and is a MIPI-DSI
132 * host. The bridge device uses a separate bus (such as I2C) to be
133 * controlled. In this case, there's no correlation between the probe
134 * of the bridge and upstream drivers, so care must be taken to avoid
135 * an endless EPROBE_DEFER loop, with each driver waiting for the
136 * other to probe.
137 *
138 * The ideal pattern to cover the last item (and all the others in the
139 * MIPI-DSI host driver case) is to split the operations like this:
140 *
141 * - The MIPI-DSI host driver must run mipi_dsi_host_register() in its
142 * probe hook. It will make sure that the MIPI-DSI host sticks around,
143 * and that the driver's bind can be called.
144 *
145 * - In its probe hook, the bridge driver must try to find its MIPI-DSI
146 * host, register as a MIPI-DSI device and attach the MIPI-DSI device
147 * to its host. The bridge driver is now functional.
148 *
149 * - In its &struct mipi_dsi_host_ops.attach hook, the MIPI-DSI host can
150 * now add its component. Its bind hook will now be called and since
151 * the bridge driver is attached and registered, we can now look for
152 * and attach it.
153 *
154 * At this point, we're now certain that both the upstream driver and
155 * the bridge driver are functional and we can't have a deadlock-like
156 * situation when probing.
157 */
158
159/**
160 * DOC: dsi bridge operations
161 *
162 * DSI host interfaces are expected to be implemented as bridges rather than
163 * encoders, however there are a few aspects of their operation that need to
164 * be defined in order to provide a consistent interface.
165 *
166 * A DSI host should keep the PHY powered down until the pre_enable operation is
167 * called. All lanes are in an undefined idle state up to this point, and it
168 * must not be assumed that it is LP-11.
169 * pre_enable should initialise the PHY, set the data lanes to LP-11, and the
170 * clock lane to either LP-11 or HS depending on the mode_flag
171 * %MIPI_DSI_CLOCK_NON_CONTINUOUS.
172 *
173 * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
174 * called before the DSI host. If the DSI peripheral requires LP-11 and/or
175 * the clock lane to be in HS mode prior to pre_enable, then it can set the
176 * &pre_enable_prev_first flag to request the pre_enable (and
177 * post_disable) order to be altered to enable the DSI host first.
178 *
179 * Either the CRTC being enabled, or the DSI host enable operation should switch
180 * the host to actively transmitting video on the data lanes.
181 *
182 * The reverse also applies. The DSI host disable operation or stopping the CRTC
183 * should stop transmitting video, and the data lanes should return to the LP-11
184 * state. The DSI host &post_disable operation should disable the PHY.
185 * If the &pre_enable_prev_first flag is set, then the DSI peripheral's
186 * bridge &post_disable will be called before the DSI host's post_disable.
187 *
188 * Whilst it is valid to call &host_transfer prior to pre_enable or after
189 * post_disable, the exact state of the lanes is undefined at this point. The
190 * DSI host should initialise the interface, transmit the data, and then disable
191 * the interface again.
192 *
193 * Ultra Low Power State (ULPS) is not explicitly supported by DRM. If
194 * implemented, it therefore needs to be handled entirely within the DSI Host
195 * driver.
196 */
197
198static DEFINE_MUTEX(bridge_lock);
199static LIST_HEAD(bridge_list);
200
201/**
202 * drm_bridge_add - add the given bridge to the global bridge list
203 *
204 * @bridge: bridge control structure
205 */
206void drm_bridge_add(struct drm_bridge *bridge)
207{
208 mutex_init(&bridge->hpd_mutex);
209
210 if (bridge->ops & DRM_BRIDGE_OP_HDMI)
211 bridge->ycbcr_420_allowed = !!(bridge->supported_formats &
212 BIT(HDMI_COLORSPACE_YUV420));
213
214 mutex_lock(&bridge_lock);
215 list_add_tail(&bridge->list, &bridge_list);
216 mutex_unlock(&bridge_lock);
217}
218EXPORT_SYMBOL(drm_bridge_add);
219
220static void drm_bridge_remove_void(void *bridge)
221{
222 drm_bridge_remove(bridge);
223}
224
225/**
226 * devm_drm_bridge_add - devm managed version of drm_bridge_add()
227 *
228 * @dev: device to tie the bridge lifetime to
229 * @bridge: bridge control structure
230 *
231 * This is the managed version of drm_bridge_add() which automatically
232 * calls drm_bridge_remove() when @dev is unbound.
233 *
234 * Return: 0 if no error or negative error code.
235 */
236int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
237{
238 drm_bridge_add(bridge);
239 return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
240}
241EXPORT_SYMBOL(devm_drm_bridge_add);
242
243/**
244 * drm_bridge_remove - remove the given bridge from the global bridge list
245 *
246 * @bridge: bridge control structure
247 */
248void drm_bridge_remove(struct drm_bridge *bridge)
249{
250 mutex_lock(&bridge_lock);
251 list_del_init(&bridge->list);
252 mutex_unlock(&bridge_lock);
253
254 mutex_destroy(&bridge->hpd_mutex);
255}
256EXPORT_SYMBOL(drm_bridge_remove);
257
258static struct drm_private_state *
259drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
260{
261 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
262 struct drm_bridge_state *state;
263
264 state = bridge->funcs->atomic_duplicate_state(bridge);
265 return state ? &state->base : NULL;
266}
267
268static void
269drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
270 struct drm_private_state *s)
271{
272 struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
273 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
274
275 bridge->funcs->atomic_destroy_state(bridge, state);
276}
277
278static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
279 .atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
280 .atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
281};
282
283/**
284 * drm_bridge_attach - attach the bridge to an encoder's chain
285 *
286 * @encoder: DRM encoder
287 * @bridge: bridge to attach
288 * @previous: previous bridge in the chain (optional)
289 * @flags: DRM_BRIDGE_ATTACH_* flags
290 *
291 * Called by a kms driver to link the bridge to an encoder's chain. The previous
292 * argument specifies the previous bridge in the chain. If NULL, the bridge is
293 * linked directly at the encoder's output. Otherwise it is linked at the
294 * previous bridge's output.
295 *
296 * If non-NULL the previous bridge must be already attached by a call to this
297 * function.
298 *
299 * Note that bridges attached to encoders are auto-detached during encoder
300 * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
301 * *not* be balanced with a drm_bridge_detach() in driver code.
302 *
303 * RETURNS:
304 * Zero on success, error code on failure
305 */
306int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
307 struct drm_bridge *previous,
308 enum drm_bridge_attach_flags flags)
309{
310 int ret;
311
312 if (!encoder || !bridge)
313 return -EINVAL;
314
315 if (previous && (!previous->dev || previous->encoder != encoder))
316 return -EINVAL;
317
318 if (bridge->dev)
319 return -EBUSY;
320
321 bridge->dev = encoder->dev;
322 bridge->encoder = encoder;
323
324 if (previous)
325 list_add(&bridge->chain_node, &previous->chain_node);
326 else
327 list_add(&bridge->chain_node, &encoder->bridge_chain);
328
329 if (bridge->funcs->attach) {
330 ret = bridge->funcs->attach(bridge, flags);
331 if (ret < 0)
332 goto err_reset_bridge;
333 }
334
335 if (bridge->funcs->atomic_reset) {
336 struct drm_bridge_state *state;
337
338 state = bridge->funcs->atomic_reset(bridge);
339 if (IS_ERR(state)) {
340 ret = PTR_ERR(state);
341 goto err_detach_bridge;
342 }
343
344 drm_atomic_private_obj_init(bridge->dev, &bridge->base,
345 &state->base,
346 &drm_bridge_priv_state_funcs);
347 }
348
349 return 0;
350
351err_detach_bridge:
352 if (bridge->funcs->detach)
353 bridge->funcs->detach(bridge);
354
355err_reset_bridge:
356 bridge->dev = NULL;
357 bridge->encoder = NULL;
358 list_del(&bridge->chain_node);
359
360 if (ret != -EPROBE_DEFER)
361 DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
362 bridge->of_node, encoder->name, ret);
363 else
364 dev_err_probe(encoder->dev->dev, -EPROBE_DEFER,
365 "failed to attach bridge %pOF to encoder %s\n",
366 bridge->of_node, encoder->name);
367
368 return ret;
369}
370EXPORT_SYMBOL(drm_bridge_attach);
371
372void drm_bridge_detach(struct drm_bridge *bridge)
373{
374 if (WARN_ON(!bridge))
375 return;
376
377 if (WARN_ON(!bridge->dev))
378 return;
379
380 if (bridge->funcs->atomic_reset)
381 drm_atomic_private_obj_fini(&bridge->base);
382
383 if (bridge->funcs->detach)
384 bridge->funcs->detach(bridge);
385
386 list_del(&bridge->chain_node);
387 bridge->dev = NULL;
388}
389
390/**
391 * DOC: bridge operations
392 *
393 * Bridge drivers expose operations through the &drm_bridge_funcs structure.
394 * The DRM internals (atomic and CRTC helpers) use the helpers defined in
395 * drm_bridge.c to call bridge operations. Those operations are divided in
396 * three big categories to support different parts of the bridge usage.
397 *
398 * - The encoder-related operations support control of the bridges in the
399 * chain, and are roughly counterparts to the &drm_encoder_helper_funcs
400 * operations. They are used by the legacy CRTC and the atomic modeset
401 * helpers to perform mode validation, fixup and setting, and enable and
402 * disable the bridge automatically.
403 *
404 * The enable and disable operations are split in
405 * &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
406 * &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
407 * finer-grained control.
408 *
409 * Bridge drivers may implement the legacy version of those operations, or
410 * the atomic version (prefixed with atomic\_), in which case they shall also
411 * implement the atomic state bookkeeping operations
412 * (&drm_bridge_funcs.atomic_duplicate_state,
413 * &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
414 * Mixing atomic and non-atomic versions of the operations is not supported.
415 *
416 * - The bus format negotiation operations
417 * &drm_bridge_funcs.atomic_get_output_bus_fmts and
418 * &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
419 * negotiate the formats transmitted between bridges in the chain when
420 * multiple formats are supported. Negotiation for formats is performed
421 * transparently for display drivers by the atomic modeset helpers. Only
422 * atomic versions of those operations exist, bridge drivers that need to
423 * implement them shall thus also implement the atomic version of the
424 * encoder-related operations. This feature is not supported by the legacy
425 * CRTC helpers.
426 *
427 * - The connector-related operations support implementing a &drm_connector
428 * based on a chain of bridges. DRM bridges traditionally create a
429 * &drm_connector for bridges meant to be used at the end of the chain. This
430 * puts additional burden on bridge drivers, especially for bridges that may
431 * be used in the middle of a chain or at the end of it. Furthermore, it
432 * requires all operations of the &drm_connector to be handled by a single
433 * bridge, which doesn't always match the hardware architecture.
434 *
435 * To simplify bridge drivers and make the connector implementation more
436 * flexible, a new model allows bridges to unconditionally skip creation of
437 * &drm_connector and instead expose &drm_bridge_funcs operations to support
438 * an externally-implemented &drm_connector. Those operations are
439 * &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
440 * &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
441 * &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
442 * implemented, display drivers shall create a &drm_connector instance for
443 * each chain of bridges, and implement those connector instances based on
444 * the bridge connector operations.
445 *
446 * Bridge drivers shall implement the connector-related operations for all
447 * the features that the bridge hardware support. For instance, if a bridge
448 * supports reading EDID, the &drm_bridge_funcs.get_edid shall be
449 * implemented. This however doesn't mean that the DDC lines are wired to the
450 * bridge on a particular platform, as they could also be connected to an I2C
451 * controller of the SoC. Support for the connector-related operations on the
452 * running platform is reported through the &drm_bridge.ops flags. Bridge
453 * drivers shall detect which operations they can support on the platform
454 * (usually this information is provided by ACPI or DT), and set the
455 * &drm_bridge.ops flags for all supported operations. A flag shall only be
456 * set if the corresponding &drm_bridge_funcs operation is implemented, but
457 * an implemented operation doesn't necessarily imply that the corresponding
458 * flag will be set. Display drivers shall use the &drm_bridge.ops flags to
459 * decide which bridge to delegate a connector operation to. This mechanism
460 * allows providing a single static const &drm_bridge_funcs instance in
461 * bridge drivers, improving security by storing function pointers in
462 * read-only memory.
463 *
464 * In order to ease transition, bridge drivers may support both the old and
465 * new models by making connector creation optional and implementing the
466 * connected-related bridge operations. Connector creation is then controlled
467 * by the flags argument to the drm_bridge_attach() function. Display drivers
468 * that support the new model and create connectors themselves shall set the
469 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
470 * connector creation. For intermediate bridges in the chain, the flag shall
471 * be passed to the drm_bridge_attach() call for the downstream bridge.
472 * Bridge drivers that implement the new model only shall return an error
473 * from their &drm_bridge_funcs.attach handler when the
474 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
475 * should use the new model, and convert the bridge drivers they use if
476 * needed, in order to gradually transition to the new model.
477 */
478
479/**
480 * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
481 * encoder chain.
482 * @bridge: bridge control structure
483 * @info: display info against which the mode shall be validated
484 * @mode: desired mode to be validated
485 *
486 * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
487 * chain, starting from the first bridge to the last. If at least one bridge
488 * does not accept the mode the function returns the error code.
489 *
490 * Note: the bridge passed should be the one closest to the encoder.
491 *
492 * RETURNS:
493 * MODE_OK on success, drm_mode_status Enum error code on failure
494 */
495enum drm_mode_status
496drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
497 const struct drm_display_info *info,
498 const struct drm_display_mode *mode)
499{
500 struct drm_encoder *encoder;
501
502 if (!bridge)
503 return MODE_OK;
504
505 encoder = bridge->encoder;
506 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
507 enum drm_mode_status ret;
508
509 if (!bridge->funcs->mode_valid)
510 continue;
511
512 ret = bridge->funcs->mode_valid(bridge, info, mode);
513 if (ret != MODE_OK)
514 return ret;
515 }
516
517 return MODE_OK;
518}
519EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
520
521/**
522 * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
523 * encoder chain
524 * @bridge: bridge control structure
525 * @mode: desired mode to be set for the encoder chain
526 * @adjusted_mode: updated mode that works for this encoder chain
527 *
528 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
529 * encoder chain, starting from the first bridge to the last.
530 *
531 * Note: the bridge passed should be the one closest to the encoder
532 */
533void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
534 const struct drm_display_mode *mode,
535 const struct drm_display_mode *adjusted_mode)
536{
537 struct drm_encoder *encoder;
538
539 if (!bridge)
540 return;
541
542 encoder = bridge->encoder;
543 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
544 if (bridge->funcs->mode_set)
545 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
546 }
547}
548EXPORT_SYMBOL(drm_bridge_chain_mode_set);
549
550/**
551 * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
552 * @bridge: bridge control structure
553 * @old_state: old atomic state
554 *
555 * Calls &drm_bridge_funcs.atomic_disable (falls back on
556 * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
557 * starting from the last bridge to the first. These are called before calling
558 * &drm_encoder_helper_funcs.atomic_disable
559 *
560 * Note: the bridge passed should be the one closest to the encoder
561 */
562void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
563 struct drm_atomic_state *old_state)
564{
565 struct drm_encoder *encoder;
566 struct drm_bridge *iter;
567
568 if (!bridge)
569 return;
570
571 encoder = bridge->encoder;
572 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
573 if (iter->funcs->atomic_disable) {
574 struct drm_bridge_state *old_bridge_state;
575
576 old_bridge_state =
577 drm_atomic_get_old_bridge_state(old_state,
578 iter);
579 if (WARN_ON(!old_bridge_state))
580 return;
581
582 iter->funcs->atomic_disable(iter, old_bridge_state);
583 } else if (iter->funcs->disable) {
584 iter->funcs->disable(iter);
585 }
586
587 if (iter == bridge)
588 break;
589 }
590}
591EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
592
593static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
594 struct drm_atomic_state *old_state)
595{
596 if (old_state && bridge->funcs->atomic_post_disable) {
597 struct drm_bridge_state *old_bridge_state;
598
599 old_bridge_state =
600 drm_atomic_get_old_bridge_state(old_state,
601 bridge);
602 if (WARN_ON(!old_bridge_state))
603 return;
604
605 bridge->funcs->atomic_post_disable(bridge,
606 old_bridge_state);
607 } else if (bridge->funcs->post_disable) {
608 bridge->funcs->post_disable(bridge);
609 }
610}
611
612/**
613 * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
614 * in the encoder chain
615 * @bridge: bridge control structure
616 * @old_state: old atomic state
617 *
618 * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
619 * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
620 * starting from the first bridge to the last. These are called after completing
621 * &drm_encoder_helper_funcs.atomic_disable
622 *
623 * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
624 * bridge will be called before the previous one to reverse the @pre_enable
625 * calling direction.
626 *
627 * Example:
628 * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
629 *
630 * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
631 * @post_disable order would be,
632 * Bridge B, Bridge A, Bridge E, Bridge D, Bridge C.
633 *
634 * Note: the bridge passed should be the one closest to the encoder
635 */
636void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
637 struct drm_atomic_state *old_state)
638{
639 struct drm_encoder *encoder;
640 struct drm_bridge *next, *limit;
641
642 if (!bridge)
643 return;
644
645 encoder = bridge->encoder;
646
647 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
648 limit = NULL;
649
650 if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
651 next = list_next_entry(bridge, chain_node);
652
653 if (next->pre_enable_prev_first) {
654 /* next bridge had requested that prev
655 * was enabled first, so disabled last
656 */
657 limit = next;
658
659 /* Find the next bridge that has NOT requested
660 * prev to be enabled first / disabled last
661 */
662 list_for_each_entry_from(next, &encoder->bridge_chain,
663 chain_node) {
664 if (!next->pre_enable_prev_first) {
665 next = list_prev_entry(next, chain_node);
666 limit = next;
667 break;
668 }
669
670 if (list_is_last(&next->chain_node,
671 &encoder->bridge_chain)) {
672 limit = next;
673 break;
674 }
675 }
676
677 /* Call these bridges in reverse order */
678 list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
679 chain_node) {
680 if (next == bridge)
681 break;
682
683 drm_atomic_bridge_call_post_disable(next,
684 old_state);
685 }
686 }
687 }
688
689 drm_atomic_bridge_call_post_disable(bridge, old_state);
690
691 if (limit)
692 /* Jump all bridges that we have already post_disabled */
693 bridge = limit;
694 }
695}
696EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
697
698static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
699 struct drm_atomic_state *old_state)
700{
701 if (old_state && bridge->funcs->atomic_pre_enable) {
702 struct drm_bridge_state *old_bridge_state;
703
704 old_bridge_state =
705 drm_atomic_get_old_bridge_state(old_state,
706 bridge);
707 if (WARN_ON(!old_bridge_state))
708 return;
709
710 bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
711 } else if (bridge->funcs->pre_enable) {
712 bridge->funcs->pre_enable(bridge);
713 }
714}
715
716/**
717 * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
718 * the encoder chain
719 * @bridge: bridge control structure
720 * @old_state: old atomic state
721 *
722 * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
723 * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
724 * starting from the last bridge to the first. These are called before calling
725 * &drm_encoder_helper_funcs.atomic_enable
726 *
727 * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
728 * prev bridge will be called before pre_enable of this bridge.
729 *
730 * Example:
731 * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
732 *
733 * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
734 * @pre_enable order would be,
735 * Bridge C, Bridge D, Bridge E, Bridge A, Bridge B.
736 *
737 * Note: the bridge passed should be the one closest to the encoder
738 */
739void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
740 struct drm_atomic_state *old_state)
741{
742 struct drm_encoder *encoder;
743 struct drm_bridge *iter, *next, *limit;
744
745 if (!bridge)
746 return;
747
748 encoder = bridge->encoder;
749
750 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
751 if (iter->pre_enable_prev_first) {
752 next = iter;
753 limit = bridge;
754 list_for_each_entry_from_reverse(next,
755 &encoder->bridge_chain,
756 chain_node) {
757 if (next == bridge)
758 break;
759
760 if (!next->pre_enable_prev_first) {
761 /* Found first bridge that does NOT
762 * request prev to be enabled first
763 */
764 limit = next;
765 break;
766 }
767 }
768
769 list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
770 /* Call requested prev bridge pre_enable
771 * in order.
772 */
773 if (next == iter)
774 /* At the first bridge to request prev
775 * bridges called first.
776 */
777 break;
778
779 drm_atomic_bridge_call_pre_enable(next, old_state);
780 }
781 }
782
783 drm_atomic_bridge_call_pre_enable(iter, old_state);
784
785 if (iter->pre_enable_prev_first)
786 /* Jump all bridges that we have already pre_enabled */
787 iter = limit;
788
789 if (iter == bridge)
790 break;
791 }
792}
793EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
794
795/**
796 * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
797 * @bridge: bridge control structure
798 * @old_state: old atomic state
799 *
800 * Calls &drm_bridge_funcs.atomic_enable (falls back on
801 * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
802 * starting from the first bridge to the last. These are called after completing
803 * &drm_encoder_helper_funcs.atomic_enable
804 *
805 * Note: the bridge passed should be the one closest to the encoder
806 */
807void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
808 struct drm_atomic_state *old_state)
809{
810 struct drm_encoder *encoder;
811
812 if (!bridge)
813 return;
814
815 encoder = bridge->encoder;
816 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
817 if (bridge->funcs->atomic_enable) {
818 struct drm_bridge_state *old_bridge_state;
819
820 old_bridge_state =
821 drm_atomic_get_old_bridge_state(old_state,
822 bridge);
823 if (WARN_ON(!old_bridge_state))
824 return;
825
826 bridge->funcs->atomic_enable(bridge, old_bridge_state);
827 } else if (bridge->funcs->enable) {
828 bridge->funcs->enable(bridge);
829 }
830 }
831}
832EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
833
834static int drm_atomic_bridge_check(struct drm_bridge *bridge,
835 struct drm_crtc_state *crtc_state,
836 struct drm_connector_state *conn_state)
837{
838 if (bridge->funcs->atomic_check) {
839 struct drm_bridge_state *bridge_state;
840 int ret;
841
842 bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
843 bridge);
844 if (WARN_ON(!bridge_state))
845 return -EINVAL;
846
847 ret = bridge->funcs->atomic_check(bridge, bridge_state,
848 crtc_state, conn_state);
849 if (ret)
850 return ret;
851 } else if (bridge->funcs->mode_fixup) {
852 if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
853 &crtc_state->adjusted_mode))
854 return -EINVAL;
855 }
856
857 return 0;
858}
859
860static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
861 struct drm_bridge *cur_bridge,
862 struct drm_crtc_state *crtc_state,
863 struct drm_connector_state *conn_state,
864 u32 out_bus_fmt)
865{
866 unsigned int i, num_in_bus_fmts = 0;
867 struct drm_bridge_state *cur_state;
868 struct drm_bridge *prev_bridge;
869 u32 *in_bus_fmts;
870 int ret;
871
872 prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
873 cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
874 cur_bridge);
875
876 /*
877 * If bus format negotiation is not supported by this bridge, let's
878 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
879 * hope that it can handle this situation gracefully (by providing
880 * appropriate default values).
881 */
882 if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
883 if (cur_bridge != first_bridge) {
884 ret = select_bus_fmt_recursive(first_bridge,
885 prev_bridge, crtc_state,
886 conn_state,
887 MEDIA_BUS_FMT_FIXED);
888 if (ret)
889 return ret;
890 }
891
892 /*
893 * Driver does not implement the atomic state hooks, but that's
894 * fine, as long as it does not access the bridge state.
895 */
896 if (cur_state) {
897 cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
898 cur_state->output_bus_cfg.format = out_bus_fmt;
899 }
900
901 return 0;
902 }
903
904 /*
905 * If the driver implements ->atomic_get_input_bus_fmts() it
906 * should also implement the atomic state hooks.
907 */
908 if (WARN_ON(!cur_state))
909 return -EINVAL;
910
911 in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
912 cur_state,
913 crtc_state,
914 conn_state,
915 out_bus_fmt,
916 &num_in_bus_fmts);
917 if (!num_in_bus_fmts)
918 return -ENOTSUPP;
919 else if (!in_bus_fmts)
920 return -ENOMEM;
921
922 if (first_bridge == cur_bridge) {
923 cur_state->input_bus_cfg.format = in_bus_fmts[0];
924 cur_state->output_bus_cfg.format = out_bus_fmt;
925 kfree(in_bus_fmts);
926 return 0;
927 }
928
929 for (i = 0; i < num_in_bus_fmts; i++) {
930 ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
931 crtc_state, conn_state,
932 in_bus_fmts[i]);
933 if (ret != -ENOTSUPP)
934 break;
935 }
936
937 if (!ret) {
938 cur_state->input_bus_cfg.format = in_bus_fmts[i];
939 cur_state->output_bus_cfg.format = out_bus_fmt;
940 }
941
942 kfree(in_bus_fmts);
943 return ret;
944}
945
946/*
947 * This function is called by &drm_atomic_bridge_chain_check() just before
948 * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
949 * It performs bus format negotiation between bridge elements. The negotiation
950 * happens in reverse order, starting from the last element in the chain up to
951 * @bridge.
952 *
953 * Negotiation starts by retrieving supported output bus formats on the last
954 * bridge element and testing them one by one. The test is recursive, meaning
955 * that for each tested output format, the whole chain will be walked backward,
956 * and each element will have to choose an input bus format that can be
957 * transcoded to the requested output format. When a bridge element does not
958 * support transcoding into a specific output format -ENOTSUPP is returned and
959 * the next bridge element will have to try a different format. If none of the
960 * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
961 *
962 * This implementation is relying on
963 * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
964 * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
965 * input/output formats.
966 *
967 * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
968 * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
969 * tries a single format: &drm_connector.display_info.bus_formats[0] if
970 * available, MEDIA_BUS_FMT_FIXED otherwise.
971 *
972 * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
973 * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
974 * bridge element that lacks this hook and asks the previous element in the
975 * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
976 * to do in that case (fail if they want to enforce bus format negotiation, or
977 * provide a reasonable default if they need to support pipelines where not
978 * all elements support bus format negotiation).
979 */
980static int
981drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
982 struct drm_crtc_state *crtc_state,
983 struct drm_connector_state *conn_state)
984{
985 struct drm_connector *conn = conn_state->connector;
986 struct drm_encoder *encoder = bridge->encoder;
987 struct drm_bridge_state *last_bridge_state;
988 unsigned int i, num_out_bus_fmts = 0;
989 struct drm_bridge *last_bridge;
990 u32 *out_bus_fmts;
991 int ret = 0;
992
993 last_bridge = list_last_entry(&encoder->bridge_chain,
994 struct drm_bridge, chain_node);
995 last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
996 last_bridge);
997
998 if (last_bridge->funcs->atomic_get_output_bus_fmts) {
999 const struct drm_bridge_funcs *funcs = last_bridge->funcs;
1000
1001 /*
1002 * If the driver implements ->atomic_get_output_bus_fmts() it
1003 * should also implement the atomic state hooks.
1004 */
1005 if (WARN_ON(!last_bridge_state))
1006 return -EINVAL;
1007
1008 out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
1009 last_bridge_state,
1010 crtc_state,
1011 conn_state,
1012 &num_out_bus_fmts);
1013 if (!num_out_bus_fmts)
1014 return -ENOTSUPP;
1015 else if (!out_bus_fmts)
1016 return -ENOMEM;
1017 } else {
1018 num_out_bus_fmts = 1;
1019 out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
1020 if (!out_bus_fmts)
1021 return -ENOMEM;
1022
1023 if (conn->display_info.num_bus_formats &&
1024 conn->display_info.bus_formats)
1025 out_bus_fmts[0] = conn->display_info.bus_formats[0];
1026 else
1027 out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
1028 }
1029
1030 for (i = 0; i < num_out_bus_fmts; i++) {
1031 ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
1032 conn_state, out_bus_fmts[i]);
1033 if (ret != -ENOTSUPP)
1034 break;
1035 }
1036
1037 kfree(out_bus_fmts);
1038
1039 return ret;
1040}
1041
1042static void
1043drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
1044 struct drm_connector *conn,
1045 struct drm_atomic_state *state)
1046{
1047 struct drm_bridge_state *bridge_state, *next_bridge_state;
1048 struct drm_bridge *next_bridge;
1049 u32 output_flags = 0;
1050
1051 bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
1052
1053 /* No bridge state attached to this bridge => nothing to propagate. */
1054 if (!bridge_state)
1055 return;
1056
1057 next_bridge = drm_bridge_get_next_bridge(bridge);
1058
1059 /*
1060 * Let's try to apply the most common case here, that is, propagate
1061 * display_info flags for the last bridge, and propagate the input
1062 * flags of the next bridge element to the output end of the current
1063 * bridge when the bridge is not the last one.
1064 * There are exceptions to this rule, like when signal inversion is
1065 * happening at the board level, but that's something drivers can deal
1066 * with from their &drm_bridge_funcs.atomic_check() implementation by
1067 * simply overriding the flags value we've set here.
1068 */
1069 if (!next_bridge) {
1070 output_flags = conn->display_info.bus_flags;
1071 } else {
1072 next_bridge_state = drm_atomic_get_new_bridge_state(state,
1073 next_bridge);
1074 /*
1075 * No bridge state attached to the next bridge, just leave the
1076 * flags to 0.
1077 */
1078 if (next_bridge_state)
1079 output_flags = next_bridge_state->input_bus_cfg.flags;
1080 }
1081
1082 bridge_state->output_bus_cfg.flags = output_flags;
1083
1084 /*
1085 * Propagate the output flags to the input end of the bridge. Again, it's
1086 * not necessarily what all bridges want, but that's what most of them
1087 * do, and by doing that by default we avoid forcing drivers to
1088 * duplicate the "dummy propagation" logic.
1089 */
1090 bridge_state->input_bus_cfg.flags = output_flags;
1091}
1092
1093/**
1094 * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1095 * @bridge: bridge control structure
1096 * @crtc_state: new CRTC state
1097 * @conn_state: new connector state
1098 *
1099 * First trigger a bus format negotiation before calling
1100 * &drm_bridge_funcs.atomic_check() (falls back on
1101 * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1102 * starting from the last bridge to the first. These are called before calling
1103 * &drm_encoder_helper_funcs.atomic_check()
1104 *
1105 * RETURNS:
1106 * 0 on success, a negative error code on failure
1107 */
1108int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1109 struct drm_crtc_state *crtc_state,
1110 struct drm_connector_state *conn_state)
1111{
1112 struct drm_connector *conn = conn_state->connector;
1113 struct drm_encoder *encoder;
1114 struct drm_bridge *iter;
1115 int ret;
1116
1117 if (!bridge)
1118 return 0;
1119
1120 ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1121 conn_state);
1122 if (ret)
1123 return ret;
1124
1125 encoder = bridge->encoder;
1126 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1127 int ret;
1128
1129 /*
1130 * Bus flags are propagated by default. If a bridge needs to
1131 * tweak the input bus flags for any reason, it should happen
1132 * in its &drm_bridge_funcs.atomic_check() implementation such
1133 * that preceding bridges in the chain can propagate the new
1134 * bus flags.
1135 */
1136 drm_atomic_bridge_propagate_bus_flags(iter, conn,
1137 crtc_state->state);
1138
1139 ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1140 if (ret)
1141 return ret;
1142
1143 if (iter == bridge)
1144 break;
1145 }
1146
1147 return 0;
1148}
1149EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1150
1151/**
1152 * drm_bridge_detect - check if anything is attached to the bridge output
1153 * @bridge: bridge control structure
1154 *
1155 * If the bridge supports output detection, as reported by the
1156 * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1157 * bridge and return the connection status. Otherwise return
1158 * connector_status_unknown.
1159 *
1160 * RETURNS:
1161 * The detection status on success, or connector_status_unknown if the bridge
1162 * doesn't support output detection.
1163 */
1164enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1165{
1166 if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1167 return connector_status_unknown;
1168
1169 return bridge->funcs->detect(bridge);
1170}
1171EXPORT_SYMBOL_GPL(drm_bridge_detect);
1172
1173/**
1174 * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1175 * @connector
1176 * @bridge: bridge control structure
1177 * @connector: the connector to fill with modes
1178 *
1179 * If the bridge supports output modes retrieval, as reported by the
1180 * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1181 * fill the connector with all valid modes and return the number of modes
1182 * added. Otherwise return 0.
1183 *
1184 * RETURNS:
1185 * The number of modes added to the connector.
1186 */
1187int drm_bridge_get_modes(struct drm_bridge *bridge,
1188 struct drm_connector *connector)
1189{
1190 if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1191 return 0;
1192
1193 return bridge->funcs->get_modes(bridge, connector);
1194}
1195EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1196
1197/**
1198 * drm_bridge_edid_read - read the EDID data of the connected display
1199 * @bridge: bridge control structure
1200 * @connector: the connector to read EDID for
1201 *
1202 * If the bridge supports output EDID retrieval, as reported by the
1203 * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.edid_read to get
1204 * the EDID and return it. Otherwise return NULL.
1205 *
1206 * RETURNS:
1207 * The retrieved EDID on success, or NULL otherwise.
1208 */
1209const struct drm_edid *drm_bridge_edid_read(struct drm_bridge *bridge,
1210 struct drm_connector *connector)
1211{
1212 if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1213 return NULL;
1214
1215 return bridge->funcs->edid_read(bridge, connector);
1216}
1217EXPORT_SYMBOL_GPL(drm_bridge_edid_read);
1218
1219/**
1220 * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1221 * @bridge: bridge control structure
1222 * @cb: hot-plug detection callback
1223 * @data: data to be passed to the hot-plug detection callback
1224 *
1225 * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1226 * and @data as hot plug notification callback. From now on the @cb will be
1227 * called with @data when an output status change is detected by the bridge,
1228 * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1229 *
1230 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1231 * bridge->ops. This function shall not be called when the flag is not set.
1232 *
1233 * Only one hot plug detection callback can be registered at a time, it is an
1234 * error to call this function when hot plug detection is already enabled for
1235 * the bridge.
1236 */
1237void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1238 void (*cb)(void *data,
1239 enum drm_connector_status status),
1240 void *data)
1241{
1242 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1243 return;
1244
1245 mutex_lock(&bridge->hpd_mutex);
1246
1247 if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1248 goto unlock;
1249
1250 bridge->hpd_cb = cb;
1251 bridge->hpd_data = data;
1252
1253 if (bridge->funcs->hpd_enable)
1254 bridge->funcs->hpd_enable(bridge);
1255
1256unlock:
1257 mutex_unlock(&bridge->hpd_mutex);
1258}
1259EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1260
1261/**
1262 * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1263 * @bridge: bridge control structure
1264 *
1265 * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1266 * plug detection callback previously registered with drm_bridge_hpd_enable().
1267 * Once this function returns the callback will not be called by the bridge
1268 * when an output status change occurs.
1269 *
1270 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1271 * bridge->ops. This function shall not be called when the flag is not set.
1272 */
1273void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1274{
1275 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1276 return;
1277
1278 mutex_lock(&bridge->hpd_mutex);
1279 if (bridge->funcs->hpd_disable)
1280 bridge->funcs->hpd_disable(bridge);
1281
1282 bridge->hpd_cb = NULL;
1283 bridge->hpd_data = NULL;
1284 mutex_unlock(&bridge->hpd_mutex);
1285}
1286EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1287
1288/**
1289 * drm_bridge_hpd_notify - notify hot plug detection events
1290 * @bridge: bridge control structure
1291 * @status: output connection status
1292 *
1293 * Bridge drivers shall call this function to report hot plug events when they
1294 * detect a change in the output status, when hot plug detection has been
1295 * enabled by drm_bridge_hpd_enable().
1296 *
1297 * This function shall be called in a context that can sleep.
1298 */
1299void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1300 enum drm_connector_status status)
1301{
1302 mutex_lock(&bridge->hpd_mutex);
1303 if (bridge->hpd_cb)
1304 bridge->hpd_cb(bridge->hpd_data, status);
1305 mutex_unlock(&bridge->hpd_mutex);
1306}
1307EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1308
1309#ifdef CONFIG_OF
1310/**
1311 * of_drm_find_bridge - find the bridge corresponding to the device node in
1312 * the global bridge list
1313 *
1314 * @np: device node
1315 *
1316 * RETURNS:
1317 * drm_bridge control struct on success, NULL on failure
1318 */
1319struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1320{
1321 struct drm_bridge *bridge;
1322
1323 mutex_lock(&bridge_lock);
1324
1325 list_for_each_entry(bridge, &bridge_list, list) {
1326 if (bridge->of_node == np) {
1327 mutex_unlock(&bridge_lock);
1328 return bridge;
1329 }
1330 }
1331
1332 mutex_unlock(&bridge_lock);
1333 return NULL;
1334}
1335EXPORT_SYMBOL(of_drm_find_bridge);
1336#endif
1337
1338MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1339MODULE_DESCRIPTION("DRM bridge infrastructure");
1340MODULE_LICENSE("GPL and additional rights");