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 /**
157  * DOC: dsi bridge operations
158  *
159  * DSI host interfaces are expected to be implemented as bridges rather than
160  * encoders, however there are a few aspects of their operation that need to
161  * be defined in order to provide a consistent interface.
162  *
163  * A DSI host should keep the PHY powered down until the pre_enable operation is
164  * called. All lanes are in an undefined idle state up to this point, and it
165  * must not be assumed that it is LP-11.
166  * pre_enable should initialise the PHY, set the data lanes to LP-11, and the
167  * clock lane to either LP-11 or HS depending on the mode_flag
168  * %MIPI_DSI_CLOCK_NON_CONTINUOUS.
169  *
170  * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
171  * called before the DSI host. If the DSI peripheral requires LP-11 and/or
172  * the clock lane to be in HS mode prior to pre_enable, then it can set the
173  * &pre_enable_prev_first flag to request the pre_enable (and
174  * post_disable) order to be altered to enable the DSI host first.
175  *
176  * Either the CRTC being enabled, or the DSI host enable operation should switch
177  * the host to actively transmitting video on the data lanes.
178  *
179  * The reverse also applies. The DSI host disable operation or stopping the CRTC
180  * should stop transmitting video, and the data lanes should return to the LP-11
181  * state. The DSI host &post_disable operation should disable the PHY.
182  * If the &pre_enable_prev_first flag is set, then the DSI peripheral's
183  * bridge &post_disable will be called before the DSI host's post_disable.
184  *
185  * Whilst it is valid to call &host_transfer prior to pre_enable or after
186  * post_disable, the exact state of the lanes is undefined at this point. The
187  * DSI host should initialise the interface, transmit the data, and then disable
188  * the interface again.
189  *
190  * Ultra Low Power State (ULPS) is not explicitly supported by DRM. If
191  * implemented, it therefore needs to be handled entirely within the DSI Host
192  * driver.
193  */
194 
195 static DEFINE_MUTEX(bridge_lock);
196 static LIST_HEAD(bridge_list);
197 
198 /**
199  * drm_bridge_add - add the given bridge to the global bridge list
200  *
201  * @bridge: bridge control structure
202  */
drm_bridge_add(struct drm_bridge * bridge)203 void drm_bridge_add(struct drm_bridge *bridge)
204 {
205 	mutex_init(&bridge->hpd_mutex);
206 
207 	mutex_lock(&bridge_lock);
208 	list_add_tail(&bridge->list, &bridge_list);
209 	mutex_unlock(&bridge_lock);
210 }
211 EXPORT_SYMBOL(drm_bridge_add);
212 
drm_bridge_remove_void(void * bridge)213 static void drm_bridge_remove_void(void *bridge)
214 {
215 	drm_bridge_remove(bridge);
216 }
217 
218 /**
219  * devm_drm_bridge_add - devm managed version of drm_bridge_add()
220  *
221  * @dev: device to tie the bridge lifetime to
222  * @bridge: bridge control structure
223  *
224  * This is the managed version of drm_bridge_add() which automatically
225  * calls drm_bridge_remove() when @dev is unbound.
226  *
227  * Return: 0 if no error or negative error code.
228  */
devm_drm_bridge_add(struct device * dev,struct drm_bridge * bridge)229 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
230 {
231 	drm_bridge_add(bridge);
232 	return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
233 }
234 EXPORT_SYMBOL(devm_drm_bridge_add);
235 
236 /**
237  * drm_bridge_remove - remove the given bridge from the global bridge list
238  *
239  * @bridge: bridge control structure
240  */
drm_bridge_remove(struct drm_bridge * bridge)241 void drm_bridge_remove(struct drm_bridge *bridge)
242 {
243 	mutex_lock(&bridge_lock);
244 	list_del_init(&bridge->list);
245 	mutex_unlock(&bridge_lock);
246 
247 	mutex_destroy(&bridge->hpd_mutex);
248 }
249 EXPORT_SYMBOL(drm_bridge_remove);
250 
251 static struct drm_private_state *
drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj * obj)252 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
253 {
254 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
255 	struct drm_bridge_state *state;
256 
257 	state = bridge->funcs->atomic_duplicate_state(bridge);
258 	return state ? &state->base : NULL;
259 }
260 
261 static void
drm_bridge_atomic_destroy_priv_state(struct drm_private_obj * obj,struct drm_private_state * s)262 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
263 				     struct drm_private_state *s)
264 {
265 	struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
266 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
267 
268 	bridge->funcs->atomic_destroy_state(bridge, state);
269 }
270 
271 static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
272 	.atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
273 	.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
274 };
275 
276 /**
277  * drm_bridge_attach - attach the bridge to an encoder's chain
278  *
279  * @encoder: DRM encoder
280  * @bridge: bridge to attach
281  * @previous: previous bridge in the chain (optional)
282  * @flags: DRM_BRIDGE_ATTACH_* flags
283  *
284  * Called by a kms driver to link the bridge to an encoder's chain. The previous
285  * argument specifies the previous bridge in the chain. If NULL, the bridge is
286  * linked directly at the encoder's output. Otherwise it is linked at the
287  * previous bridge's output.
288  *
289  * If non-NULL the previous bridge must be already attached by a call to this
290  * function.
291  *
292  * Note that bridges attached to encoders are auto-detached during encoder
293  * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
294  * *not* be balanced with a drm_bridge_detach() in driver code.
295  *
296  * RETURNS:
297  * Zero on success, error code on failure
298  */
drm_bridge_attach(struct drm_encoder * encoder,struct drm_bridge * bridge,struct drm_bridge * previous,enum drm_bridge_attach_flags flags)299 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
300 		      struct drm_bridge *previous,
301 		      enum drm_bridge_attach_flags flags)
302 {
303 	int ret;
304 
305 	if (!encoder || !bridge)
306 		return -EINVAL;
307 
308 	if (previous && (!previous->dev || previous->encoder != encoder))
309 		return -EINVAL;
310 
311 	if (bridge->dev)
312 		return -EBUSY;
313 
314 	bridge->dev = encoder->dev;
315 	bridge->encoder = encoder;
316 
317 	if (previous)
318 		list_add(&bridge->chain_node, &previous->chain_node);
319 	else
320 		list_add(&bridge->chain_node, &encoder->bridge_chain);
321 
322 	if (bridge->funcs->attach) {
323 		ret = bridge->funcs->attach(bridge, flags);
324 		if (ret < 0)
325 			goto err_reset_bridge;
326 	}
327 
328 	if (bridge->funcs->atomic_reset) {
329 		struct drm_bridge_state *state;
330 
331 		state = bridge->funcs->atomic_reset(bridge);
332 		if (IS_ERR(state)) {
333 			ret = PTR_ERR(state);
334 			goto err_detach_bridge;
335 		}
336 
337 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,
338 					    &state->base,
339 					    &drm_bridge_priv_state_funcs);
340 	}
341 
342 	return 0;
343 
344 err_detach_bridge:
345 	if (bridge->funcs->detach)
346 		bridge->funcs->detach(bridge);
347 
348 err_reset_bridge:
349 	bridge->dev = NULL;
350 	bridge->encoder = NULL;
351 	list_del(&bridge->chain_node);
352 
353 #ifdef CONFIG_OF
354 	DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
355 		  bridge->of_node, encoder->name, ret);
356 #else
357 	DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
358 		  encoder->name, ret);
359 #endif
360 
361 	return ret;
362 }
363 EXPORT_SYMBOL(drm_bridge_attach);
364 
drm_bridge_detach(struct drm_bridge * bridge)365 void drm_bridge_detach(struct drm_bridge *bridge)
366 {
367 	if (WARN_ON(!bridge))
368 		return;
369 
370 	if (WARN_ON(!bridge->dev))
371 		return;
372 
373 	if (bridge->funcs->atomic_reset)
374 		drm_atomic_private_obj_fini(&bridge->base);
375 
376 	if (bridge->funcs->detach)
377 		bridge->funcs->detach(bridge);
378 
379 	list_del(&bridge->chain_node);
380 	bridge->dev = NULL;
381 }
382 
383 /**
384  * DOC: bridge operations
385  *
386  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
387  * The DRM internals (atomic and CRTC helpers) use the helpers defined in
388  * drm_bridge.c to call bridge operations. Those operations are divided in
389  * three big categories to support different parts of the bridge usage.
390  *
391  * - The encoder-related operations support control of the bridges in the
392  *   chain, and are roughly counterparts to the &drm_encoder_helper_funcs
393  *   operations. They are used by the legacy CRTC and the atomic modeset
394  *   helpers to perform mode validation, fixup and setting, and enable and
395  *   disable the bridge automatically.
396  *
397  *   The enable and disable operations are split in
398  *   &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
399  *   &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
400  *   finer-grained control.
401  *
402  *   Bridge drivers may implement the legacy version of those operations, or
403  *   the atomic version (prefixed with atomic\_), in which case they shall also
404  *   implement the atomic state bookkeeping operations
405  *   (&drm_bridge_funcs.atomic_duplicate_state,
406  *   &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
407  *   Mixing atomic and non-atomic versions of the operations is not supported.
408  *
409  * - The bus format negotiation operations
410  *   &drm_bridge_funcs.atomic_get_output_bus_fmts and
411  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
412  *   negotiate the formats transmitted between bridges in the chain when
413  *   multiple formats are supported. Negotiation for formats is performed
414  *   transparently for display drivers by the atomic modeset helpers. Only
415  *   atomic versions of those operations exist, bridge drivers that need to
416  *   implement them shall thus also implement the atomic version of the
417  *   encoder-related operations. This feature is not supported by the legacy
418  *   CRTC helpers.
419  *
420  * - The connector-related operations support implementing a &drm_connector
421  *   based on a chain of bridges. DRM bridges traditionally create a
422  *   &drm_connector for bridges meant to be used at the end of the chain. This
423  *   puts additional burden on bridge drivers, especially for bridges that may
424  *   be used in the middle of a chain or at the end of it. Furthermore, it
425  *   requires all operations of the &drm_connector to be handled by a single
426  *   bridge, which doesn't always match the hardware architecture.
427  *
428  *   To simplify bridge drivers and make the connector implementation more
429  *   flexible, a new model allows bridges to unconditionally skip creation of
430  *   &drm_connector and instead expose &drm_bridge_funcs operations to support
431  *   an externally-implemented &drm_connector. Those operations are
432  *   &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
433  *   &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
434  *   &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
435  *   implemented, display drivers shall create a &drm_connector instance for
436  *   each chain of bridges, and implement those connector instances based on
437  *   the bridge connector operations.
438  *
439  *   Bridge drivers shall implement the connector-related operations for all
440  *   the features that the bridge hardware support. For instance, if a bridge
441  *   supports reading EDID, the &drm_bridge_funcs.get_edid shall be
442  *   implemented. This however doesn't mean that the DDC lines are wired to the
443  *   bridge on a particular platform, as they could also be connected to an I2C
444  *   controller of the SoC. Support for the connector-related operations on the
445  *   running platform is reported through the &drm_bridge.ops flags. Bridge
446  *   drivers shall detect which operations they can support on the platform
447  *   (usually this information is provided by ACPI or DT), and set the
448  *   &drm_bridge.ops flags for all supported operations. A flag shall only be
449  *   set if the corresponding &drm_bridge_funcs operation is implemented, but
450  *   an implemented operation doesn't necessarily imply that the corresponding
451  *   flag will be set. Display drivers shall use the &drm_bridge.ops flags to
452  *   decide which bridge to delegate a connector operation to. This mechanism
453  *   allows providing a single static const &drm_bridge_funcs instance in
454  *   bridge drivers, improving security by storing function pointers in
455  *   read-only memory.
456  *
457  *   In order to ease transition, bridge drivers may support both the old and
458  *   new models by making connector creation optional and implementing the
459  *   connected-related bridge operations. Connector creation is then controlled
460  *   by the flags argument to the drm_bridge_attach() function. Display drivers
461  *   that support the new model and create connectors themselves shall set the
462  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
463  *   connector creation. For intermediate bridges in the chain, the flag shall
464  *   be passed to the drm_bridge_attach() call for the downstream bridge.
465  *   Bridge drivers that implement the new model only shall return an error
466  *   from their &drm_bridge_funcs.attach handler when the
467  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
468  *   should use the new model, and convert the bridge drivers they use if
469  *   needed, in order to gradually transition to the new model.
470  */
471 
472 /**
473  * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
474  *				 encoder chain
475  * @bridge: bridge control structure
476  * @mode: desired mode to be set for the bridge
477  * @adjusted_mode: updated mode that works for this bridge
478  *
479  * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
480  * encoder chain, starting from the first bridge to the last.
481  *
482  * Note: the bridge passed should be the one closest to the encoder
483  *
484  * RETURNS:
485  * true on success, false on failure
486  */
drm_bridge_chain_mode_fixup(struct drm_bridge * bridge,const struct drm_display_mode * mode,struct drm_display_mode * adjusted_mode)487 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
488 				 const struct drm_display_mode *mode,
489 				 struct drm_display_mode *adjusted_mode)
490 {
491 	struct drm_encoder *encoder;
492 
493 	if (!bridge)
494 		return true;
495 
496 	encoder = bridge->encoder;
497 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
498 		if (!bridge->funcs->mode_fixup)
499 			continue;
500 
501 		if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
502 			return false;
503 	}
504 
505 	return true;
506 }
507 EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
508 
509 /**
510  * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
511  *				 encoder chain.
512  * @bridge: bridge control structure
513  * @info: display info against which the mode shall be validated
514  * @mode: desired mode to be validated
515  *
516  * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
517  * chain, starting from the first bridge to the last. If at least one bridge
518  * does not accept the mode the function returns the error code.
519  *
520  * Note: the bridge passed should be the one closest to the encoder.
521  *
522  * RETURNS:
523  * MODE_OK on success, drm_mode_status Enum error code on failure
524  */
525 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)526 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
527 			    const struct drm_display_info *info,
528 			    const struct drm_display_mode *mode)
529 {
530 	struct drm_encoder *encoder;
531 
532 	if (!bridge)
533 		return MODE_OK;
534 
535 	encoder = bridge->encoder;
536 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
537 		enum drm_mode_status ret;
538 
539 		if (!bridge->funcs->mode_valid)
540 			continue;
541 
542 		ret = bridge->funcs->mode_valid(bridge, info, mode);
543 		if (ret != MODE_OK)
544 			return ret;
545 	}
546 
547 	return MODE_OK;
548 }
549 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
550 
551 /**
552  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
553  *			       encoder chain
554  * @bridge: bridge control structure
555  * @mode: desired mode to be set for the encoder chain
556  * @adjusted_mode: updated mode that works for this encoder chain
557  *
558  * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
559  * encoder chain, starting from the first bridge to the last.
560  *
561  * Note: the bridge passed should be the one closest to the encoder
562  */
drm_bridge_chain_mode_set(struct drm_bridge * bridge,const struct drm_display_mode * mode,const struct drm_display_mode * adjusted_mode)563 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
564 			       const struct drm_display_mode *mode,
565 			       const struct drm_display_mode *adjusted_mode)
566 {
567 	struct drm_encoder *encoder;
568 
569 	if (!bridge)
570 		return;
571 
572 	encoder = bridge->encoder;
573 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
574 		if (bridge->funcs->mode_set)
575 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);
576 	}
577 }
578 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
579 
580 /**
581  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
582  * @bridge: bridge control structure
583  * @old_state: old atomic state
584  *
585  * Calls &drm_bridge_funcs.atomic_disable (falls back on
586  * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
587  * starting from the last bridge to the first. These are called before calling
588  * &drm_encoder_helper_funcs.atomic_disable
589  *
590  * Note: the bridge passed should be the one closest to the encoder
591  */
drm_atomic_bridge_chain_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)592 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
593 				     struct drm_atomic_state *old_state)
594 {
595 	struct drm_encoder *encoder;
596 	struct drm_bridge *iter;
597 
598 	if (!bridge)
599 		return;
600 
601 	encoder = bridge->encoder;
602 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
603 		if (iter->funcs->atomic_disable) {
604 			struct drm_bridge_state *old_bridge_state;
605 
606 			old_bridge_state =
607 				drm_atomic_get_old_bridge_state(old_state,
608 								iter);
609 			if (WARN_ON(!old_bridge_state))
610 				return;
611 
612 			iter->funcs->atomic_disable(iter, old_bridge_state);
613 		} else if (iter->funcs->disable) {
614 			iter->funcs->disable(iter);
615 		}
616 
617 		if (iter == bridge)
618 			break;
619 	}
620 }
621 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
622 
drm_atomic_bridge_call_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)623 static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
624 						struct drm_atomic_state *old_state)
625 {
626 	if (old_state && bridge->funcs->atomic_post_disable) {
627 		struct drm_bridge_state *old_bridge_state;
628 
629 		old_bridge_state =
630 			drm_atomic_get_old_bridge_state(old_state,
631 							bridge);
632 		if (WARN_ON(!old_bridge_state))
633 			return;
634 
635 		bridge->funcs->atomic_post_disable(bridge,
636 						   old_bridge_state);
637 	} else if (bridge->funcs->post_disable) {
638 		bridge->funcs->post_disable(bridge);
639 	}
640 }
641 
642 /**
643  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
644  *					  in the encoder chain
645  * @bridge: bridge control structure
646  * @old_state: old atomic state
647  *
648  * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
649  * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
650  * starting from the first bridge to the last. These are called after completing
651  * &drm_encoder_helper_funcs.atomic_disable
652  *
653  * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
654  * bridge will be called before the previous one to reverse the @pre_enable
655  * calling direction.
656  *
657  * Note: the bridge passed should be the one closest to the encoder
658  */
drm_atomic_bridge_chain_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)659 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
660 					  struct drm_atomic_state *old_state)
661 {
662 	struct drm_encoder *encoder;
663 	struct drm_bridge *next, *limit;
664 
665 	if (!bridge)
666 		return;
667 
668 	encoder = bridge->encoder;
669 
670 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
671 		limit = NULL;
672 
673 		if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
674 			next = list_next_entry(bridge, chain_node);
675 
676 			if (next->pre_enable_prev_first) {
677 				/* next bridge had requested that prev
678 				 * was enabled first, so disabled last
679 				 */
680 				limit = next;
681 
682 				/* Find the next bridge that has NOT requested
683 				 * prev to be enabled first / disabled last
684 				 */
685 				list_for_each_entry_from(next, &encoder->bridge_chain,
686 							 chain_node) {
687 					if (next->pre_enable_prev_first) {
688 						next = list_prev_entry(next, chain_node);
689 						limit = next;
690 						break;
691 					}
692 				}
693 
694 				/* Call these bridges in reverse order */
695 				list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
696 								 chain_node) {
697 					if (next == bridge)
698 						break;
699 
700 					drm_atomic_bridge_call_post_disable(next,
701 									    old_state);
702 				}
703 			}
704 		}
705 
706 		drm_atomic_bridge_call_post_disable(bridge, old_state);
707 
708 		if (limit)
709 			/* Jump all bridges that we have already post_disabled */
710 			bridge = limit;
711 	}
712 }
713 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
714 
drm_atomic_bridge_call_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)715 static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
716 					      struct drm_atomic_state *old_state)
717 {
718 	if (old_state && bridge->funcs->atomic_pre_enable) {
719 		struct drm_bridge_state *old_bridge_state;
720 
721 		old_bridge_state =
722 			drm_atomic_get_old_bridge_state(old_state,
723 							bridge);
724 		if (WARN_ON(!old_bridge_state))
725 			return;
726 
727 		bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
728 	} else if (bridge->funcs->pre_enable) {
729 		bridge->funcs->pre_enable(bridge);
730 	}
731 }
732 
733 /**
734  * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
735  *					the encoder chain
736  * @bridge: bridge control structure
737  * @old_state: old atomic state
738  *
739  * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
740  * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
741  * starting from the last bridge to the first. These are called before calling
742  * &drm_encoder_helper_funcs.atomic_enable
743  *
744  * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
745  * prev bridge will be called before pre_enable of this bridge.
746  *
747  * Note: the bridge passed should be the one closest to the encoder
748  */
drm_atomic_bridge_chain_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)749 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
750 					struct drm_atomic_state *old_state)
751 {
752 	struct drm_encoder *encoder;
753 	struct drm_bridge *iter, *next, *limit;
754 
755 	if (!bridge)
756 		return;
757 
758 	encoder = bridge->encoder;
759 
760 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
761 		if (iter->pre_enable_prev_first) {
762 			next = iter;
763 			limit = bridge;
764 			list_for_each_entry_from_reverse(next,
765 							 &encoder->bridge_chain,
766 							 chain_node) {
767 				if (next == bridge)
768 					break;
769 
770 				if (!next->pre_enable_prev_first) {
771 					/* Found first bridge that does NOT
772 					 * request prev to be enabled first
773 					 */
774 					limit = list_prev_entry(next, chain_node);
775 					break;
776 				}
777 			}
778 
779 			list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
780 				/* Call requested prev bridge pre_enable
781 				 * in order.
782 				 */
783 				if (next == iter)
784 					/* At the first bridge to request prev
785 					 * bridges called first.
786 					 */
787 					break;
788 
789 				drm_atomic_bridge_call_pre_enable(next, old_state);
790 			}
791 		}
792 
793 		drm_atomic_bridge_call_pre_enable(iter, old_state);
794 
795 		if (iter->pre_enable_prev_first)
796 			/* Jump all bridges that we have already pre_enabled */
797 			iter = limit;
798 
799 		if (iter == bridge)
800 			break;
801 	}
802 }
803 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
804 
805 /**
806  * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
807  * @bridge: bridge control structure
808  * @old_state: old atomic state
809  *
810  * Calls &drm_bridge_funcs.atomic_enable (falls back on
811  * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
812  * starting from the first bridge to the last. These are called after completing
813  * &drm_encoder_helper_funcs.atomic_enable
814  *
815  * Note: the bridge passed should be the one closest to the encoder
816  */
drm_atomic_bridge_chain_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)817 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
818 				    struct drm_atomic_state *old_state)
819 {
820 	struct drm_encoder *encoder;
821 
822 	if (!bridge)
823 		return;
824 
825 	encoder = bridge->encoder;
826 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
827 		if (bridge->funcs->atomic_enable) {
828 			struct drm_bridge_state *old_bridge_state;
829 
830 			old_bridge_state =
831 				drm_atomic_get_old_bridge_state(old_state,
832 								bridge);
833 			if (WARN_ON(!old_bridge_state))
834 				return;
835 
836 			bridge->funcs->atomic_enable(bridge, old_bridge_state);
837 		} else if (bridge->funcs->enable) {
838 			bridge->funcs->enable(bridge);
839 		}
840 	}
841 }
842 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
843 
drm_atomic_bridge_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)844 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
845 				   struct drm_crtc_state *crtc_state,
846 				   struct drm_connector_state *conn_state)
847 {
848 	if (bridge->funcs->atomic_check) {
849 		struct drm_bridge_state *bridge_state;
850 		int ret;
851 
852 		bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
853 							       bridge);
854 		if (WARN_ON(!bridge_state))
855 			return -EINVAL;
856 
857 		ret = bridge->funcs->atomic_check(bridge, bridge_state,
858 						  crtc_state, conn_state);
859 		if (ret)
860 			return ret;
861 	} else if (bridge->funcs->mode_fixup) {
862 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
863 					       &crtc_state->adjusted_mode))
864 			return -EINVAL;
865 	}
866 
867 	return 0;
868 }
869 
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)870 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
871 				    struct drm_bridge *cur_bridge,
872 				    struct drm_crtc_state *crtc_state,
873 				    struct drm_connector_state *conn_state,
874 				    u32 out_bus_fmt)
875 {
876 	unsigned int i, num_in_bus_fmts = 0;
877 	struct drm_bridge_state *cur_state;
878 	struct drm_bridge *prev_bridge;
879 	u32 *in_bus_fmts;
880 	int ret;
881 
882 	prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
883 	cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
884 						    cur_bridge);
885 
886 	/*
887 	 * If bus format negotiation is not supported by this bridge, let's
888 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
889 	 * hope that it can handle this situation gracefully (by providing
890 	 * appropriate default values).
891 	 */
892 	if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
893 		if (cur_bridge != first_bridge) {
894 			ret = select_bus_fmt_recursive(first_bridge,
895 						       prev_bridge, crtc_state,
896 						       conn_state,
897 						       MEDIA_BUS_FMT_FIXED);
898 			if (ret)
899 				return ret;
900 		}
901 
902 		/*
903 		 * Driver does not implement the atomic state hooks, but that's
904 		 * fine, as long as it does not access the bridge state.
905 		 */
906 		if (cur_state) {
907 			cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
908 			cur_state->output_bus_cfg.format = out_bus_fmt;
909 		}
910 
911 		return 0;
912 	}
913 
914 	/*
915 	 * If the driver implements ->atomic_get_input_bus_fmts() it
916 	 * should also implement the atomic state hooks.
917 	 */
918 	if (WARN_ON(!cur_state))
919 		return -EINVAL;
920 
921 	in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
922 							cur_state,
923 							crtc_state,
924 							conn_state,
925 							out_bus_fmt,
926 							&num_in_bus_fmts);
927 	if (!num_in_bus_fmts)
928 		return -ENOTSUPP;
929 	else if (!in_bus_fmts)
930 		return -ENOMEM;
931 
932 	if (first_bridge == cur_bridge) {
933 		cur_state->input_bus_cfg.format = in_bus_fmts[0];
934 		cur_state->output_bus_cfg.format = out_bus_fmt;
935 		kfree(in_bus_fmts);
936 		return 0;
937 	}
938 
939 	for (i = 0; i < num_in_bus_fmts; i++) {
940 		ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
941 					       crtc_state, conn_state,
942 					       in_bus_fmts[i]);
943 		if (ret != -ENOTSUPP)
944 			break;
945 	}
946 
947 	if (!ret) {
948 		cur_state->input_bus_cfg.format = in_bus_fmts[i];
949 		cur_state->output_bus_cfg.format = out_bus_fmt;
950 	}
951 
952 	kfree(in_bus_fmts);
953 	return ret;
954 }
955 
956 /*
957  * This function is called by &drm_atomic_bridge_chain_check() just before
958  * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
959  * It performs bus format negotiation between bridge elements. The negotiation
960  * happens in reverse order, starting from the last element in the chain up to
961  * @bridge.
962  *
963  * Negotiation starts by retrieving supported output bus formats on the last
964  * bridge element and testing them one by one. The test is recursive, meaning
965  * that for each tested output format, the whole chain will be walked backward,
966  * and each element will have to choose an input bus format that can be
967  * transcoded to the requested output format. When a bridge element does not
968  * support transcoding into a specific output format -ENOTSUPP is returned and
969  * the next bridge element will have to try a different format. If none of the
970  * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
971  *
972  * This implementation is relying on
973  * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
974  * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
975  * input/output formats.
976  *
977  * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
978  * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
979  * tries a single format: &drm_connector.display_info.bus_formats[0] if
980  * available, MEDIA_BUS_FMT_FIXED otherwise.
981  *
982  * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
983  * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
984  * bridge element that lacks this hook and asks the previous element in the
985  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
986  * to do in that case (fail if they want to enforce bus format negotiation, or
987  * provide a reasonable default if they need to support pipelines where not
988  * all elements support bus format negotiation).
989  */
990 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)991 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
992 					struct drm_crtc_state *crtc_state,
993 					struct drm_connector_state *conn_state)
994 {
995 	struct drm_connector *conn = conn_state->connector;
996 	struct drm_encoder *encoder = bridge->encoder;
997 	struct drm_bridge_state *last_bridge_state;
998 	unsigned int i, num_out_bus_fmts = 0;
999 	struct drm_bridge *last_bridge;
1000 	u32 *out_bus_fmts;
1001 	int ret = 0;
1002 
1003 	last_bridge = list_last_entry(&encoder->bridge_chain,
1004 				      struct drm_bridge, chain_node);
1005 	last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
1006 							    last_bridge);
1007 
1008 	if (last_bridge->funcs->atomic_get_output_bus_fmts) {
1009 		const struct drm_bridge_funcs *funcs = last_bridge->funcs;
1010 
1011 		/*
1012 		 * If the driver implements ->atomic_get_output_bus_fmts() it
1013 		 * should also implement the atomic state hooks.
1014 		 */
1015 		if (WARN_ON(!last_bridge_state))
1016 			return -EINVAL;
1017 
1018 		out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
1019 							last_bridge_state,
1020 							crtc_state,
1021 							conn_state,
1022 							&num_out_bus_fmts);
1023 		if (!num_out_bus_fmts)
1024 			return -ENOTSUPP;
1025 		else if (!out_bus_fmts)
1026 			return -ENOMEM;
1027 	} else {
1028 		num_out_bus_fmts = 1;
1029 		out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
1030 		if (!out_bus_fmts)
1031 			return -ENOMEM;
1032 
1033 		if (conn->display_info.num_bus_formats &&
1034 		    conn->display_info.bus_formats)
1035 			out_bus_fmts[0] = conn->display_info.bus_formats[0];
1036 		else
1037 			out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
1038 	}
1039 
1040 	for (i = 0; i < num_out_bus_fmts; i++) {
1041 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
1042 					       conn_state, out_bus_fmts[i]);
1043 		if (ret != -ENOTSUPP)
1044 			break;
1045 	}
1046 
1047 	kfree(out_bus_fmts);
1048 
1049 	return ret;
1050 }
1051 
1052 static void
drm_atomic_bridge_propagate_bus_flags(struct drm_bridge * bridge,struct drm_connector * conn,struct drm_atomic_state * state)1053 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
1054 				      struct drm_connector *conn,
1055 				      struct drm_atomic_state *state)
1056 {
1057 	struct drm_bridge_state *bridge_state, *next_bridge_state;
1058 	struct drm_bridge *next_bridge;
1059 	u32 output_flags = 0;
1060 
1061 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
1062 
1063 	/* No bridge state attached to this bridge => nothing to propagate. */
1064 	if (!bridge_state)
1065 		return;
1066 
1067 	next_bridge = drm_bridge_get_next_bridge(bridge);
1068 
1069 	/*
1070 	 * Let's try to apply the most common case here, that is, propagate
1071 	 * display_info flags for the last bridge, and propagate the input
1072 	 * flags of the next bridge element to the output end of the current
1073 	 * bridge when the bridge is not the last one.
1074 	 * There are exceptions to this rule, like when signal inversion is
1075 	 * happening at the board level, but that's something drivers can deal
1076 	 * with from their &drm_bridge_funcs.atomic_check() implementation by
1077 	 * simply overriding the flags value we've set here.
1078 	 */
1079 	if (!next_bridge) {
1080 		output_flags = conn->display_info.bus_flags;
1081 	} else {
1082 		next_bridge_state = drm_atomic_get_new_bridge_state(state,
1083 								next_bridge);
1084 		/*
1085 		 * No bridge state attached to the next bridge, just leave the
1086 		 * flags to 0.
1087 		 */
1088 		if (next_bridge_state)
1089 			output_flags = next_bridge_state->input_bus_cfg.flags;
1090 	}
1091 
1092 	bridge_state->output_bus_cfg.flags = output_flags;
1093 
1094 	/*
1095 	 * Propagate the output flags to the input end of the bridge. Again, it's
1096 	 * not necessarily what all bridges want, but that's what most of them
1097 	 * do, and by doing that by default we avoid forcing drivers to
1098 	 * duplicate the "dummy propagation" logic.
1099 	 */
1100 	bridge_state->input_bus_cfg.flags = output_flags;
1101 }
1102 
1103 /**
1104  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1105  * @bridge: bridge control structure
1106  * @crtc_state: new CRTC state
1107  * @conn_state: new connector state
1108  *
1109  * First trigger a bus format negotiation before calling
1110  * &drm_bridge_funcs.atomic_check() (falls back on
1111  * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1112  * starting from the last bridge to the first. These are called before calling
1113  * &drm_encoder_helper_funcs.atomic_check()
1114  *
1115  * RETURNS:
1116  * 0 on success, a negative error code on failure
1117  */
drm_atomic_bridge_chain_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)1118 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1119 				  struct drm_crtc_state *crtc_state,
1120 				  struct drm_connector_state *conn_state)
1121 {
1122 	struct drm_connector *conn = conn_state->connector;
1123 	struct drm_encoder *encoder;
1124 	struct drm_bridge *iter;
1125 	int ret;
1126 
1127 	if (!bridge)
1128 		return 0;
1129 
1130 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1131 						      conn_state);
1132 	if (ret)
1133 		return ret;
1134 
1135 	encoder = bridge->encoder;
1136 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1137 		int ret;
1138 
1139 		/*
1140 		 * Bus flags are propagated by default. If a bridge needs to
1141 		 * tweak the input bus flags for any reason, it should happen
1142 		 * in its &drm_bridge_funcs.atomic_check() implementation such
1143 		 * that preceding bridges in the chain can propagate the new
1144 		 * bus flags.
1145 		 */
1146 		drm_atomic_bridge_propagate_bus_flags(iter, conn,
1147 						      crtc_state->state);
1148 
1149 		ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1150 		if (ret)
1151 			return ret;
1152 
1153 		if (iter == bridge)
1154 			break;
1155 	}
1156 
1157 	return 0;
1158 }
1159 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1160 
1161 /**
1162  * drm_bridge_detect - check if anything is attached to the bridge output
1163  * @bridge: bridge control structure
1164  *
1165  * If the bridge supports output detection, as reported by the
1166  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1167  * bridge and return the connection status. Otherwise return
1168  * connector_status_unknown.
1169  *
1170  * RETURNS:
1171  * The detection status on success, or connector_status_unknown if the bridge
1172  * doesn't support output detection.
1173  */
drm_bridge_detect(struct drm_bridge * bridge)1174 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1175 {
1176 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1177 		return connector_status_unknown;
1178 
1179 	return bridge->funcs->detect(bridge);
1180 }
1181 EXPORT_SYMBOL_GPL(drm_bridge_detect);
1182 
1183 /**
1184  * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1185  * @connector
1186  * @bridge: bridge control structure
1187  * @connector: the connector to fill with modes
1188  *
1189  * If the bridge supports output modes retrieval, as reported by the
1190  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1191  * fill the connector with all valid modes and return the number of modes
1192  * added. Otherwise return 0.
1193  *
1194  * RETURNS:
1195  * The number of modes added to the connector.
1196  */
drm_bridge_get_modes(struct drm_bridge * bridge,struct drm_connector * connector)1197 int drm_bridge_get_modes(struct drm_bridge *bridge,
1198 			 struct drm_connector *connector)
1199 {
1200 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1201 		return 0;
1202 
1203 	return bridge->funcs->get_modes(bridge, connector);
1204 }
1205 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1206 
1207 /**
1208  * drm_bridge_get_edid - get the EDID data of the connected display
1209  * @bridge: bridge control structure
1210  * @connector: the connector to read EDID for
1211  *
1212  * If the bridge supports output EDID retrieval, as reported by the
1213  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1214  * get the EDID and return it. Otherwise return NULL.
1215  *
1216  * RETURNS:
1217  * The retrieved EDID on success, or NULL otherwise.
1218  */
drm_bridge_get_edid(struct drm_bridge * bridge,struct drm_connector * connector)1219 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1220 				 struct drm_connector *connector)
1221 {
1222 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1223 		return NULL;
1224 
1225 	return bridge->funcs->get_edid(bridge, connector);
1226 }
1227 EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1228 
1229 /**
1230  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1231  * @bridge: bridge control structure
1232  * @cb: hot-plug detection callback
1233  * @data: data to be passed to the hot-plug detection callback
1234  *
1235  * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1236  * and @data as hot plug notification callback. From now on the @cb will be
1237  * called with @data when an output status change is detected by the bridge,
1238  * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1239  *
1240  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1241  * bridge->ops. This function shall not be called when the flag is not set.
1242  *
1243  * Only one hot plug detection callback can be registered at a time, it is an
1244  * error to call this function when hot plug detection is already enabled for
1245  * the bridge.
1246  */
drm_bridge_hpd_enable(struct drm_bridge * bridge,void (* cb)(void * data,enum drm_connector_status status),void * data)1247 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1248 			   void (*cb)(void *data,
1249 				      enum drm_connector_status status),
1250 			   void *data)
1251 {
1252 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1253 		return;
1254 
1255 	mutex_lock(&bridge->hpd_mutex);
1256 
1257 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1258 		goto unlock;
1259 
1260 	bridge->hpd_cb = cb;
1261 	bridge->hpd_data = data;
1262 
1263 	if (bridge->funcs->hpd_enable)
1264 		bridge->funcs->hpd_enable(bridge);
1265 
1266 unlock:
1267 	mutex_unlock(&bridge->hpd_mutex);
1268 }
1269 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1270 
1271 /**
1272  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1273  * @bridge: bridge control structure
1274  *
1275  * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1276  * plug detection callback previously registered with drm_bridge_hpd_enable().
1277  * Once this function returns the callback will not be called by the bridge
1278  * when an output status change occurs.
1279  *
1280  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1281  * bridge->ops. This function shall not be called when the flag is not set.
1282  */
drm_bridge_hpd_disable(struct drm_bridge * bridge)1283 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1284 {
1285 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1286 		return;
1287 
1288 	mutex_lock(&bridge->hpd_mutex);
1289 	if (bridge->funcs->hpd_disable)
1290 		bridge->funcs->hpd_disable(bridge);
1291 
1292 	bridge->hpd_cb = NULL;
1293 	bridge->hpd_data = NULL;
1294 	mutex_unlock(&bridge->hpd_mutex);
1295 }
1296 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1297 
1298 /**
1299  * drm_bridge_hpd_notify - notify hot plug detection events
1300  * @bridge: bridge control structure
1301  * @status: output connection status
1302  *
1303  * Bridge drivers shall call this function to report hot plug events when they
1304  * detect a change in the output status, when hot plug detection has been
1305  * enabled by drm_bridge_hpd_enable().
1306  *
1307  * This function shall be called in a context that can sleep.
1308  */
drm_bridge_hpd_notify(struct drm_bridge * bridge,enum drm_connector_status status)1309 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1310 			   enum drm_connector_status status)
1311 {
1312 	mutex_lock(&bridge->hpd_mutex);
1313 	if (bridge->hpd_cb)
1314 		bridge->hpd_cb(bridge->hpd_data, status);
1315 	mutex_unlock(&bridge->hpd_mutex);
1316 }
1317 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1318 
1319 #ifdef CONFIG_OF
1320 /**
1321  * of_drm_find_bridge - find the bridge corresponding to the device node in
1322  *			the global bridge list
1323  *
1324  * @np: device node
1325  *
1326  * RETURNS:
1327  * drm_bridge control struct on success, NULL on failure
1328  */
of_drm_find_bridge(struct device_node * np)1329 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1330 {
1331 	struct drm_bridge *bridge;
1332 
1333 	mutex_lock(&bridge_lock);
1334 
1335 	list_for_each_entry(bridge, &bridge_list, list) {
1336 		if (bridge->of_node == np) {
1337 			mutex_unlock(&bridge_lock);
1338 			return bridge;
1339 		}
1340 	}
1341 
1342 	mutex_unlock(&bridge_lock);
1343 	return NULL;
1344 }
1345 EXPORT_SYMBOL(of_drm_find_bridge);
1346 #endif
1347 
1348 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1349 MODULE_DESCRIPTION("DRM bridge infrastructure");
1350 MODULE_LICENSE("GPL and additional rights");
1351