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