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_debugfs.h>
31 #include <drm/drm_bridge.h>
32 #include <drm/drm_encoder.h>
33 #include <drm/drm_file.h>
34 #include <drm/drm_of.h>
35 #include <drm/drm_print.h>
36 
37 #include "drm_crtc_internal.h"
38 
39 /**
40  * DOC: overview
41  *
42  * &struct drm_bridge represents a device that hangs on to an encoder. These are
43  * handy when a regular &drm_encoder entity isn't enough to represent the entire
44  * encoder chain.
45  *
46  * A bridge is always attached to a single &drm_encoder at a time, but can be
47  * either connected to it directly, or through a chain of bridges::
48  *
49  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
50  *
51  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
52  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
53  * Chaining multiple bridges to the output of a bridge, or the same bridge to
54  * the output of different bridges, is not supported.
55  *
56  * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
57  * CRTCs, encoders or connectors and hence are not visible to userspace. They
58  * just provide additional hooks to get the desired output at the end of the
59  * encoder chain.
60  */
61 
62 /**
63  * DOC:	display driver integration
64  *
65  * Display drivers are responsible for linking encoders with the first bridge
66  * in the chains. This is done by acquiring the appropriate bridge with
67  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
68  * encoder with a call to drm_bridge_attach().
69  *
70  * Bridges are responsible for linking themselves with the next bridge in the
71  * chain, if any. This is done the same way as for encoders, with the call to
72  * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
73  *
74  * Once these links are created, the bridges can participate along with encoder
75  * functions to perform mode validation and fixup (through
76  * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
77  * setting (through drm_bridge_chain_mode_set()), enable (through
78  * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
79  * and disable (through drm_atomic_bridge_chain_disable() and
80  * drm_atomic_bridge_chain_post_disable()). Those functions call the
81  * corresponding operations provided in &drm_bridge_funcs in sequence for all
82  * bridges in the chain.
83  *
84  * For display drivers that use the atomic helpers
85  * drm_atomic_helper_check_modeset(),
86  * drm_atomic_helper_commit_modeset_enables() and
87  * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
88  * commit check and commit tail handlers, or through the higher-level
89  * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
90  * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
91  * requires no intervention from the driver. For other drivers, the relevant
92  * DRM bridge chain functions shall be called manually.
93  *
94  * Bridges also participate in implementing the &drm_connector at the end of
95  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
96  * helper to create the &drm_connector, or implement it manually on top of the
97  * connector-related operations exposed by the bridge (see the overview
98  * documentation of bridge operations for more details).
99  */
100 
101 /**
102  * DOC: special care dsi
103  *
104  * The interaction between the bridges and other frameworks involved in
105  * the probing of the upstream driver and the bridge driver can be
106  * challenging. Indeed, there's multiple cases that needs to be
107  * considered:
108  *
109  * - The upstream driver doesn't use the component framework and isn't a
110  *   MIPI-DSI host. In this case, the bridge driver will probe at some
111  *   point and the upstream driver should try to probe again by returning
112  *   EPROBE_DEFER as long as the bridge driver hasn't probed.
113  *
114  * - The upstream driver doesn't use the component framework, but is a
115  *   MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
116  *   controlled. In this case, the bridge device is a child of the
117  *   display device and when it will probe it's assured that the display
118  *   device (and MIPI-DSI host) is present. The upstream driver will be
119  *   assured that the bridge driver is connected between the
120  *   &mipi_dsi_host_ops.attach and &mipi_dsi_host_ops.detach operations.
121  *   Therefore, it must run mipi_dsi_host_register() in its probe
122  *   function, and then run drm_bridge_attach() in its
123  *   &mipi_dsi_host_ops.attach hook.
124  *
125  * - The upstream driver uses the component framework and is a MIPI-DSI
126  *   host. The bridge device uses the MIPI-DCS commands to be
127  *   controlled. This is the same situation than above, and can run
128  *   mipi_dsi_host_register() in either its probe or bind hooks.
129  *
130  * - The upstream driver uses the component framework and is a MIPI-DSI
131  *   host. The bridge device uses a separate bus (such as I2C) to be
132  *   controlled. In this case, there's no correlation between the probe
133  *   of the bridge and upstream drivers, so care must be taken to avoid
134  *   an endless EPROBE_DEFER loop, with each driver waiting for the
135  *   other to probe.
136  *
137  * The ideal pattern to cover the last item (and all the others in the
138  * MIPI-DSI host driver case) is to split the operations like this:
139  *
140  * - The MIPI-DSI host driver must run mipi_dsi_host_register() in its
141  *   probe hook. It will make sure that the MIPI-DSI host sticks around,
142  *   and that the driver's bind can be called.
143  *
144  * - In its probe hook, the bridge driver must try to find its MIPI-DSI
145  *   host, register as a MIPI-DSI device and attach the MIPI-DSI device
146  *   to its host. The bridge driver is now functional.
147  *
148  * - In its &struct mipi_dsi_host_ops.attach hook, the MIPI-DSI host can
149  *   now add its component. Its bind hook will now be called and since
150  *   the bridge driver is attached and registered, we can now look for
151  *   and attach it.
152  *
153  * At this point, we're now certain that both the upstream driver and
154  * the bridge driver are functional and we can't have a deadlock-like
155  * situation when probing.
156  */
157 
158 /**
159  * DOC: dsi bridge operations
160  *
161  * DSI host interfaces are expected to be implemented as bridges rather than
162  * encoders, however there are a few aspects of their operation that need to
163  * be defined in order to provide a consistent interface.
164  *
165  * A DSI host should keep the PHY powered down until the pre_enable operation is
166  * called. All lanes are in an undefined idle state up to this point, and it
167  * must not be assumed that it is LP-11.
168  * pre_enable should initialise the PHY, set the data lanes to LP-11, and the
169  * clock lane to either LP-11 or HS depending on the mode_flag
170  * %MIPI_DSI_CLOCK_NON_CONTINUOUS.
171  *
172  * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
173  * called before the DSI host. If the DSI peripheral requires LP-11 and/or
174  * the clock lane to be in HS mode prior to pre_enable, then it can set the
175  * &pre_enable_prev_first flag to request the pre_enable (and
176  * post_disable) order to be altered to enable the DSI host first.
177  *
178  * Either the CRTC being enabled, or the DSI host enable operation should switch
179  * the host to actively transmitting video on the data lanes.
180  *
181  * The reverse also applies. The DSI host disable operation or stopping the CRTC
182  * should stop transmitting video, and the data lanes should return to the LP-11
183  * state. The DSI host &post_disable operation should disable the PHY.
184  * If the &pre_enable_prev_first flag is set, then the DSI peripheral's
185  * bridge &post_disable will be called before the DSI host's post_disable.
186  *
187  * Whilst it is valid to call &host_transfer prior to pre_enable or after
188  * post_disable, the exact state of the lanes is undefined at this point. The
189  * DSI host should initialise the interface, transmit the data, and then disable
190  * the interface again.
191  *
192  * Ultra Low Power State (ULPS) is not explicitly supported by DRM. If
193  * implemented, it therefore needs to be handled entirely within the DSI Host
194  * driver.
195  */
196 
197 static DEFINE_MUTEX(bridge_lock);
198 static LIST_HEAD(bridge_list);
199 
200 /**
201  * drm_bridge_add - add the given bridge to the global bridge list
202  *
203  * @bridge: bridge control structure
204  */
drm_bridge_add(struct drm_bridge * bridge)205 void drm_bridge_add(struct drm_bridge *bridge)
206 {
207 	mutex_init(&bridge->hpd_mutex);
208 
209 	mutex_lock(&bridge_lock);
210 	list_add_tail(&bridge->list, &bridge_list);
211 	mutex_unlock(&bridge_lock);
212 }
213 EXPORT_SYMBOL(drm_bridge_add);
214 
drm_bridge_remove_void(void * bridge)215 static void drm_bridge_remove_void(void *bridge)
216 {
217 	drm_bridge_remove(bridge);
218 }
219 
220 /**
221  * devm_drm_bridge_add - devm managed version of drm_bridge_add()
222  *
223  * @dev: device to tie the bridge lifetime to
224  * @bridge: bridge control structure
225  *
226  * This is the managed version of drm_bridge_add() which automatically
227  * calls drm_bridge_remove() when @dev is unbound.
228  *
229  * Return: 0 if no error or negative error code.
230  */
devm_drm_bridge_add(struct device * dev,struct drm_bridge * bridge)231 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
232 {
233 	drm_bridge_add(bridge);
234 	return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
235 }
236 EXPORT_SYMBOL(devm_drm_bridge_add);
237 
238 /**
239  * drm_bridge_remove - remove the given bridge from the global bridge list
240  *
241  * @bridge: bridge control structure
242  */
drm_bridge_remove(struct drm_bridge * bridge)243 void drm_bridge_remove(struct drm_bridge *bridge)
244 {
245 	mutex_lock(&bridge_lock);
246 	list_del_init(&bridge->list);
247 	mutex_unlock(&bridge_lock);
248 
249 	mutex_destroy(&bridge->hpd_mutex);
250 }
251 EXPORT_SYMBOL(drm_bridge_remove);
252 
253 static struct drm_private_state *
drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj * obj)254 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
255 {
256 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
257 	struct drm_bridge_state *state;
258 
259 	state = bridge->funcs->atomic_duplicate_state(bridge);
260 	return state ? &state->base : NULL;
261 }
262 
263 static void
drm_bridge_atomic_destroy_priv_state(struct drm_private_obj * obj,struct drm_private_state * s)264 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
265 				     struct drm_private_state *s)
266 {
267 	struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
268 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
269 
270 	bridge->funcs->atomic_destroy_state(bridge, state);
271 }
272 
273 static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
274 	.atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
275 	.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
276 };
277 
278 /**
279  * drm_bridge_attach - attach the bridge to an encoder's chain
280  *
281  * @encoder: DRM encoder
282  * @bridge: bridge to attach
283  * @previous: previous bridge in the chain (optional)
284  * @flags: DRM_BRIDGE_ATTACH_* flags
285  *
286  * Called by a kms driver to link the bridge to an encoder's chain. The previous
287  * argument specifies the previous bridge in the chain. If NULL, the bridge is
288  * linked directly at the encoder's output. Otherwise it is linked at the
289  * previous bridge's output.
290  *
291  * If non-NULL the previous bridge must be already attached by a call to this
292  * function.
293  *
294  * Note that bridges attached to encoders are auto-detached during encoder
295  * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
296  * *not* be balanced with a drm_bridge_detach() in driver code.
297  *
298  * RETURNS:
299  * Zero on success, error code on failure
300  */
drm_bridge_attach(struct drm_encoder * encoder,struct drm_bridge * bridge,struct drm_bridge * previous,enum drm_bridge_attach_flags flags)301 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
302 		      struct drm_bridge *previous,
303 		      enum drm_bridge_attach_flags flags)
304 {
305 	int ret;
306 
307 	if (!encoder || !bridge)
308 		return -EINVAL;
309 
310 	if (previous && (!previous->dev || previous->encoder != encoder))
311 		return -EINVAL;
312 
313 	if (bridge->dev)
314 		return -EBUSY;
315 
316 	bridge->dev = encoder->dev;
317 	bridge->encoder = encoder;
318 
319 	if (previous)
320 		list_add(&bridge->chain_node, &previous->chain_node);
321 	else
322 		list_add(&bridge->chain_node, &encoder->bridge_chain);
323 
324 	if (bridge->funcs->attach) {
325 		ret = bridge->funcs->attach(bridge, flags);
326 		if (ret < 0)
327 			goto err_reset_bridge;
328 	}
329 
330 	if (bridge->funcs->atomic_reset) {
331 		struct drm_bridge_state *state;
332 
333 		state = bridge->funcs->atomic_reset(bridge);
334 		if (IS_ERR(state)) {
335 			ret = PTR_ERR(state);
336 			goto err_detach_bridge;
337 		}
338 
339 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,
340 					    &state->base,
341 					    &drm_bridge_priv_state_funcs);
342 	}
343 
344 	return 0;
345 
346 err_detach_bridge:
347 	if (bridge->funcs->detach)
348 		bridge->funcs->detach(bridge);
349 
350 err_reset_bridge:
351 	bridge->dev = NULL;
352 	bridge->encoder = NULL;
353 	list_del(&bridge->chain_node);
354 
355 #ifdef CONFIG_OF
356 	DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
357 		  bridge->of_node, encoder->name, ret);
358 #else
359 	DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
360 		  encoder->name, ret);
361 #endif
362 
363 	return ret;
364 }
365 EXPORT_SYMBOL(drm_bridge_attach);
366 
drm_bridge_detach(struct drm_bridge * bridge)367 void drm_bridge_detach(struct drm_bridge *bridge)
368 {
369 	if (WARN_ON(!bridge))
370 		return;
371 
372 	if (WARN_ON(!bridge->dev))
373 		return;
374 
375 	if (bridge->funcs->atomic_reset)
376 		drm_atomic_private_obj_fini(&bridge->base);
377 
378 	if (bridge->funcs->detach)
379 		bridge->funcs->detach(bridge);
380 
381 	list_del(&bridge->chain_node);
382 	bridge->dev = NULL;
383 }
384 
385 /**
386  * DOC: bridge operations
387  *
388  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
389  * The DRM internals (atomic and CRTC helpers) use the helpers defined in
390  * drm_bridge.c to call bridge operations. Those operations are divided in
391  * three big categories to support different parts of the bridge usage.
392  *
393  * - The encoder-related operations support control of the bridges in the
394  *   chain, and are roughly counterparts to the &drm_encoder_helper_funcs
395  *   operations. They are used by the legacy CRTC and the atomic modeset
396  *   helpers to perform mode validation, fixup and setting, and enable and
397  *   disable the bridge automatically.
398  *
399  *   The enable and disable operations are split in
400  *   &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
401  *   &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
402  *   finer-grained control.
403  *
404  *   Bridge drivers may implement the legacy version of those operations, or
405  *   the atomic version (prefixed with atomic\_), in which case they shall also
406  *   implement the atomic state bookkeeping operations
407  *   (&drm_bridge_funcs.atomic_duplicate_state,
408  *   &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
409  *   Mixing atomic and non-atomic versions of the operations is not supported.
410  *
411  * - The bus format negotiation operations
412  *   &drm_bridge_funcs.atomic_get_output_bus_fmts and
413  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
414  *   negotiate the formats transmitted between bridges in the chain when
415  *   multiple formats are supported. Negotiation for formats is performed
416  *   transparently for display drivers by the atomic modeset helpers. Only
417  *   atomic versions of those operations exist, bridge drivers that need to
418  *   implement them shall thus also implement the atomic version of the
419  *   encoder-related operations. This feature is not supported by the legacy
420  *   CRTC helpers.
421  *
422  * - The connector-related operations support implementing a &drm_connector
423  *   based on a chain of bridges. DRM bridges traditionally create a
424  *   &drm_connector for bridges meant to be used at the end of the chain. This
425  *   puts additional burden on bridge drivers, especially for bridges that may
426  *   be used in the middle of a chain or at the end of it. Furthermore, it
427  *   requires all operations of the &drm_connector to be handled by a single
428  *   bridge, which doesn't always match the hardware architecture.
429  *
430  *   To simplify bridge drivers and make the connector implementation more
431  *   flexible, a new model allows bridges to unconditionally skip creation of
432  *   &drm_connector and instead expose &drm_bridge_funcs operations to support
433  *   an externally-implemented &drm_connector. Those operations are
434  *   &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
435  *   &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
436  *   &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
437  *   implemented, display drivers shall create a &drm_connector instance for
438  *   each chain of bridges, and implement those connector instances based on
439  *   the bridge connector operations.
440  *
441  *   Bridge drivers shall implement the connector-related operations for all
442  *   the features that the bridge hardware support. For instance, if a bridge
443  *   supports reading EDID, the &drm_bridge_funcs.get_edid shall be
444  *   implemented. This however doesn't mean that the DDC lines are wired to the
445  *   bridge on a particular platform, as they could also be connected to an I2C
446  *   controller of the SoC. Support for the connector-related operations on the
447  *   running platform is reported through the &drm_bridge.ops flags. Bridge
448  *   drivers shall detect which operations they can support on the platform
449  *   (usually this information is provided by ACPI or DT), and set the
450  *   &drm_bridge.ops flags for all supported operations. A flag shall only be
451  *   set if the corresponding &drm_bridge_funcs operation is implemented, but
452  *   an implemented operation doesn't necessarily imply that the corresponding
453  *   flag will be set. Display drivers shall use the &drm_bridge.ops flags to
454  *   decide which bridge to delegate a connector operation to. This mechanism
455  *   allows providing a single static const &drm_bridge_funcs instance in
456  *   bridge drivers, improving security by storing function pointers in
457  *   read-only memory.
458  *
459  *   In order to ease transition, bridge drivers may support both the old and
460  *   new models by making connector creation optional and implementing the
461  *   connected-related bridge operations. Connector creation is then controlled
462  *   by the flags argument to the drm_bridge_attach() function. Display drivers
463  *   that support the new model and create connectors themselves shall set the
464  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
465  *   connector creation. For intermediate bridges in the chain, the flag shall
466  *   be passed to the drm_bridge_attach() call for the downstream bridge.
467  *   Bridge drivers that implement the new model only shall return an error
468  *   from their &drm_bridge_funcs.attach handler when the
469  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
470  *   should use the new model, and convert the bridge drivers they use if
471  *   needed, in order to gradually transition to the new model.
472  */
473 
474 /**
475  * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
476  *				 encoder chain
477  * @bridge: bridge control structure
478  * @mode: desired mode to be set for the bridge
479  * @adjusted_mode: updated mode that works for this bridge
480  *
481  * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
482  * encoder chain, starting from the first bridge to the last.
483  *
484  * Note: the bridge passed should be the one closest to the encoder
485  *
486  * RETURNS:
487  * true on success, false on failure
488  */
drm_bridge_chain_mode_fixup(struct drm_bridge * bridge,const struct drm_display_mode * mode,struct drm_display_mode * adjusted_mode)489 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
490 				 const struct drm_display_mode *mode,
491 				 struct drm_display_mode *adjusted_mode)
492 {
493 	struct drm_encoder *encoder;
494 
495 	if (!bridge)
496 		return true;
497 
498 	encoder = bridge->encoder;
499 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
500 		if (!bridge->funcs->mode_fixup)
501 			continue;
502 
503 		if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
504 			return false;
505 	}
506 
507 	return true;
508 }
509 EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
510 
511 /**
512  * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
513  *				 encoder chain.
514  * @bridge: bridge control structure
515  * @info: display info against which the mode shall be validated
516  * @mode: desired mode to be validated
517  *
518  * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
519  * chain, starting from the first bridge to the last. If at least one bridge
520  * does not accept the mode the function returns the error code.
521  *
522  * Note: the bridge passed should be the one closest to the encoder.
523  *
524  * RETURNS:
525  * MODE_OK on success, drm_mode_status Enum error code on failure
526  */
527 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)528 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
529 			    const struct drm_display_info *info,
530 			    const struct drm_display_mode *mode)
531 {
532 	struct drm_encoder *encoder;
533 
534 	if (!bridge)
535 		return MODE_OK;
536 
537 	encoder = bridge->encoder;
538 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
539 		enum drm_mode_status ret;
540 
541 		if (!bridge->funcs->mode_valid)
542 			continue;
543 
544 		ret = bridge->funcs->mode_valid(bridge, info, mode);
545 		if (ret != MODE_OK)
546 			return ret;
547 	}
548 
549 	return MODE_OK;
550 }
551 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
552 
553 /**
554  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
555  *			       encoder chain
556  * @bridge: bridge control structure
557  * @mode: desired mode to be set for the encoder chain
558  * @adjusted_mode: updated mode that works for this encoder chain
559  *
560  * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
561  * encoder chain, starting from the first bridge to the last.
562  *
563  * Note: the bridge passed should be the one closest to the encoder
564  */
drm_bridge_chain_mode_set(struct drm_bridge * bridge,const struct drm_display_mode * mode,const struct drm_display_mode * adjusted_mode)565 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
566 			       const struct drm_display_mode *mode,
567 			       const struct drm_display_mode *adjusted_mode)
568 {
569 	struct drm_encoder *encoder;
570 
571 	if (!bridge)
572 		return;
573 
574 	encoder = bridge->encoder;
575 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
576 		if (bridge->funcs->mode_set)
577 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);
578 	}
579 }
580 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
581 
582 /**
583  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
584  * @bridge: bridge control structure
585  * @old_state: old atomic state
586  *
587  * Calls &drm_bridge_funcs.atomic_disable (falls back on
588  * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
589  * starting from the last bridge to the first. These are called before calling
590  * &drm_encoder_helper_funcs.atomic_disable
591  *
592  * Note: the bridge passed should be the one closest to the encoder
593  */
drm_atomic_bridge_chain_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)594 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
595 				     struct drm_atomic_state *old_state)
596 {
597 	struct drm_encoder *encoder;
598 	struct drm_bridge *iter;
599 
600 	if (!bridge)
601 		return;
602 
603 	encoder = bridge->encoder;
604 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
605 		if (iter->funcs->atomic_disable) {
606 			struct drm_bridge_state *old_bridge_state;
607 
608 			old_bridge_state =
609 				drm_atomic_get_old_bridge_state(old_state,
610 								iter);
611 			if (WARN_ON(!old_bridge_state))
612 				return;
613 
614 			iter->funcs->atomic_disable(iter, old_bridge_state);
615 		} else if (iter->funcs->disable) {
616 			iter->funcs->disable(iter);
617 		}
618 
619 		if (iter == bridge)
620 			break;
621 	}
622 }
623 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
624 
drm_atomic_bridge_call_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)625 static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
626 						struct drm_atomic_state *old_state)
627 {
628 	if (old_state && bridge->funcs->atomic_post_disable) {
629 		struct drm_bridge_state *old_bridge_state;
630 
631 		old_bridge_state =
632 			drm_atomic_get_old_bridge_state(old_state,
633 							bridge);
634 		if (WARN_ON(!old_bridge_state))
635 			return;
636 
637 		bridge->funcs->atomic_post_disable(bridge,
638 						   old_bridge_state);
639 	} else if (bridge->funcs->post_disable) {
640 		bridge->funcs->post_disable(bridge);
641 	}
642 }
643 
644 /**
645  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
646  *					  in the encoder chain
647  * @bridge: bridge control structure
648  * @old_state: old atomic state
649  *
650  * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
651  * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
652  * starting from the first bridge to the last. These are called after completing
653  * &drm_encoder_helper_funcs.atomic_disable
654  *
655  * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
656  * bridge will be called before the previous one to reverse the @pre_enable
657  * calling direction.
658  *
659  * Note: the bridge passed should be the one closest to the encoder
660  */
drm_atomic_bridge_chain_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)661 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
662 					  struct drm_atomic_state *old_state)
663 {
664 	struct drm_encoder *encoder;
665 	struct drm_bridge *next, *limit;
666 
667 	if (!bridge)
668 		return;
669 
670 	encoder = bridge->encoder;
671 
672 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
673 		limit = NULL;
674 
675 		if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
676 			next = list_next_entry(bridge, chain_node);
677 
678 			if (next->pre_enable_prev_first) {
679 				/* next bridge had requested that prev
680 				 * was enabled first, so disabled last
681 				 */
682 				limit = next;
683 
684 				/* Find the next bridge that has NOT requested
685 				 * prev to be enabled first / disabled last
686 				 */
687 				list_for_each_entry_from(next, &encoder->bridge_chain,
688 							 chain_node) {
689 					if (next->pre_enable_prev_first) {
690 						next = list_prev_entry(next, chain_node);
691 						limit = next;
692 						break;
693 					}
694 				}
695 
696 				/* Call these bridges in reverse order */
697 				list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
698 								 chain_node) {
699 					if (next == bridge)
700 						break;
701 
702 					drm_atomic_bridge_call_post_disable(next,
703 									    old_state);
704 				}
705 			}
706 		}
707 
708 		drm_atomic_bridge_call_post_disable(bridge, old_state);
709 
710 		if (limit)
711 			/* Jump all bridges that we have already post_disabled */
712 			bridge = limit;
713 	}
714 }
715 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
716 
drm_atomic_bridge_call_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)717 static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
718 					      struct drm_atomic_state *old_state)
719 {
720 	if (old_state && bridge->funcs->atomic_pre_enable) {
721 		struct drm_bridge_state *old_bridge_state;
722 
723 		old_bridge_state =
724 			drm_atomic_get_old_bridge_state(old_state,
725 							bridge);
726 		if (WARN_ON(!old_bridge_state))
727 			return;
728 
729 		bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
730 	} else if (bridge->funcs->pre_enable) {
731 		bridge->funcs->pre_enable(bridge);
732 	}
733 }
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  * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
747  * prev bridge will be called before pre_enable of this bridge.
748  *
749  * Note: the bridge passed should be the one closest to the encoder
750  */
drm_atomic_bridge_chain_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)751 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
752 					struct drm_atomic_state *old_state)
753 {
754 	struct drm_encoder *encoder;
755 	struct drm_bridge *iter, *next, *limit;
756 
757 	if (!bridge)
758 		return;
759 
760 	encoder = bridge->encoder;
761 
762 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
763 		if (iter->pre_enable_prev_first) {
764 			next = iter;
765 			limit = bridge;
766 			list_for_each_entry_from_reverse(next,
767 							 &encoder->bridge_chain,
768 							 chain_node) {
769 				if (next == bridge)
770 					break;
771 
772 				if (!next->pre_enable_prev_first) {
773 					/* Found first bridge that does NOT
774 					 * request prev to be enabled first
775 					 */
776 					limit = list_prev_entry(next, chain_node);
777 					break;
778 				}
779 			}
780 
781 			list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
782 				/* Call requested prev bridge pre_enable
783 				 * in order.
784 				 */
785 				if (next == iter)
786 					/* At the first bridge to request prev
787 					 * bridges called first.
788 					 */
789 					break;
790 
791 				drm_atomic_bridge_call_pre_enable(next, old_state);
792 			}
793 		}
794 
795 		drm_atomic_bridge_call_pre_enable(iter, old_state);
796 
797 		if (iter->pre_enable_prev_first)
798 			/* Jump all bridges that we have already pre_enabled */
799 			iter = limit;
800 
801 		if (iter == bridge)
802 			break;
803 	}
804 }
805 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
806 
807 /**
808  * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
809  * @bridge: bridge control structure
810  * @old_state: old atomic state
811  *
812  * Calls &drm_bridge_funcs.atomic_enable (falls back on
813  * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
814  * starting from the first bridge to the last. These are called after completing
815  * &drm_encoder_helper_funcs.atomic_enable
816  *
817  * Note: the bridge passed should be the one closest to the encoder
818  */
drm_atomic_bridge_chain_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)819 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
820 				    struct drm_atomic_state *old_state)
821 {
822 	struct drm_encoder *encoder;
823 
824 	if (!bridge)
825 		return;
826 
827 	encoder = bridge->encoder;
828 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
829 		if (bridge->funcs->atomic_enable) {
830 			struct drm_bridge_state *old_bridge_state;
831 
832 			old_bridge_state =
833 				drm_atomic_get_old_bridge_state(old_state,
834 								bridge);
835 			if (WARN_ON(!old_bridge_state))
836 				return;
837 
838 			bridge->funcs->atomic_enable(bridge, old_bridge_state);
839 		} else if (bridge->funcs->enable) {
840 			bridge->funcs->enable(bridge);
841 		}
842 	}
843 }
844 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
845 
drm_atomic_bridge_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)846 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
847 				   struct drm_crtc_state *crtc_state,
848 				   struct drm_connector_state *conn_state)
849 {
850 	if (bridge->funcs->atomic_check) {
851 		struct drm_bridge_state *bridge_state;
852 		int ret;
853 
854 		bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
855 							       bridge);
856 		if (WARN_ON(!bridge_state))
857 			return -EINVAL;
858 
859 		ret = bridge->funcs->atomic_check(bridge, bridge_state,
860 						  crtc_state, conn_state);
861 		if (ret)
862 			return ret;
863 	} else if (bridge->funcs->mode_fixup) {
864 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
865 					       &crtc_state->adjusted_mode))
866 			return -EINVAL;
867 	}
868 
869 	return 0;
870 }
871 
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)872 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
873 				    struct drm_bridge *cur_bridge,
874 				    struct drm_crtc_state *crtc_state,
875 				    struct drm_connector_state *conn_state,
876 				    u32 out_bus_fmt)
877 {
878 	unsigned int i, num_in_bus_fmts = 0;
879 	struct drm_bridge_state *cur_state;
880 	struct drm_bridge *prev_bridge;
881 	u32 *in_bus_fmts;
882 	int ret;
883 
884 	prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
885 	cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
886 						    cur_bridge);
887 
888 	/*
889 	 * If bus format negotiation is not supported by this bridge, let's
890 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
891 	 * hope that it can handle this situation gracefully (by providing
892 	 * appropriate default values).
893 	 */
894 	if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
895 		if (cur_bridge != first_bridge) {
896 			ret = select_bus_fmt_recursive(first_bridge,
897 						       prev_bridge, crtc_state,
898 						       conn_state,
899 						       MEDIA_BUS_FMT_FIXED);
900 			if (ret)
901 				return ret;
902 		}
903 
904 		/*
905 		 * Driver does not implement the atomic state hooks, but that's
906 		 * fine, as long as it does not access the bridge state.
907 		 */
908 		if (cur_state) {
909 			cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
910 			cur_state->output_bus_cfg.format = out_bus_fmt;
911 		}
912 
913 		return 0;
914 	}
915 
916 	/*
917 	 * If the driver implements ->atomic_get_input_bus_fmts() it
918 	 * should also implement the atomic state hooks.
919 	 */
920 	if (WARN_ON(!cur_state))
921 		return -EINVAL;
922 
923 	in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
924 							cur_state,
925 							crtc_state,
926 							conn_state,
927 							out_bus_fmt,
928 							&num_in_bus_fmts);
929 	if (!num_in_bus_fmts)
930 		return -ENOTSUPP;
931 	else if (!in_bus_fmts)
932 		return -ENOMEM;
933 
934 	if (first_bridge == cur_bridge) {
935 		cur_state->input_bus_cfg.format = in_bus_fmts[0];
936 		cur_state->output_bus_cfg.format = out_bus_fmt;
937 		kfree(in_bus_fmts);
938 		return 0;
939 	}
940 
941 	for (i = 0; i < num_in_bus_fmts; i++) {
942 		ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
943 					       crtc_state, conn_state,
944 					       in_bus_fmts[i]);
945 		if (ret != -ENOTSUPP)
946 			break;
947 	}
948 
949 	if (!ret) {
950 		cur_state->input_bus_cfg.format = in_bus_fmts[i];
951 		cur_state->output_bus_cfg.format = out_bus_fmt;
952 	}
953 
954 	kfree(in_bus_fmts);
955 	return ret;
956 }
957 
958 /*
959  * This function is called by &drm_atomic_bridge_chain_check() just before
960  * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
961  * It performs bus format negotiation between bridge elements. The negotiation
962  * happens in reverse order, starting from the last element in the chain up to
963  * @bridge.
964  *
965  * Negotiation starts by retrieving supported output bus formats on the last
966  * bridge element and testing them one by one. The test is recursive, meaning
967  * that for each tested output format, the whole chain will be walked backward,
968  * and each element will have to choose an input bus format that can be
969  * transcoded to the requested output format. When a bridge element does not
970  * support transcoding into a specific output format -ENOTSUPP is returned and
971  * the next bridge element will have to try a different format. If none of the
972  * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
973  *
974  * This implementation is relying on
975  * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
976  * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
977  * input/output formats.
978  *
979  * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
980  * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
981  * tries a single format: &drm_connector.display_info.bus_formats[0] if
982  * available, MEDIA_BUS_FMT_FIXED otherwise.
983  *
984  * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
985  * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
986  * bridge element that lacks this hook and asks the previous element in the
987  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
988  * to do in that case (fail if they want to enforce bus format negotiation, or
989  * provide a reasonable default if they need to support pipelines where not
990  * all elements support bus format negotiation).
991  */
992 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)993 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
994 					struct drm_crtc_state *crtc_state,
995 					struct drm_connector_state *conn_state)
996 {
997 	struct drm_connector *conn = conn_state->connector;
998 	struct drm_encoder *encoder = bridge->encoder;
999 	struct drm_bridge_state *last_bridge_state;
1000 	unsigned int i, num_out_bus_fmts = 0;
1001 	struct drm_bridge *last_bridge;
1002 	u32 *out_bus_fmts;
1003 	int ret = 0;
1004 
1005 	last_bridge = list_last_entry(&encoder->bridge_chain,
1006 				      struct drm_bridge, chain_node);
1007 	last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
1008 							    last_bridge);
1009 
1010 	if (last_bridge->funcs->atomic_get_output_bus_fmts) {
1011 		const struct drm_bridge_funcs *funcs = last_bridge->funcs;
1012 
1013 		/*
1014 		 * If the driver implements ->atomic_get_output_bus_fmts() it
1015 		 * should also implement the atomic state hooks.
1016 		 */
1017 		if (WARN_ON(!last_bridge_state))
1018 			return -EINVAL;
1019 
1020 		out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
1021 							last_bridge_state,
1022 							crtc_state,
1023 							conn_state,
1024 							&num_out_bus_fmts);
1025 		if (!num_out_bus_fmts)
1026 			return -ENOTSUPP;
1027 		else if (!out_bus_fmts)
1028 			return -ENOMEM;
1029 	} else {
1030 		num_out_bus_fmts = 1;
1031 		out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
1032 		if (!out_bus_fmts)
1033 			return -ENOMEM;
1034 
1035 		if (conn->display_info.num_bus_formats &&
1036 		    conn->display_info.bus_formats)
1037 			out_bus_fmts[0] = conn->display_info.bus_formats[0];
1038 		else
1039 			out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
1040 	}
1041 
1042 	for (i = 0; i < num_out_bus_fmts; i++) {
1043 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
1044 					       conn_state, out_bus_fmts[i]);
1045 		if (ret != -ENOTSUPP)
1046 			break;
1047 	}
1048 
1049 	kfree(out_bus_fmts);
1050 
1051 	return ret;
1052 }
1053 
1054 static void
drm_atomic_bridge_propagate_bus_flags(struct drm_bridge * bridge,struct drm_connector * conn,struct drm_atomic_state * state)1055 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
1056 				      struct drm_connector *conn,
1057 				      struct drm_atomic_state *state)
1058 {
1059 	struct drm_bridge_state *bridge_state, *next_bridge_state;
1060 	struct drm_bridge *next_bridge;
1061 	u32 output_flags = 0;
1062 
1063 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
1064 
1065 	/* No bridge state attached to this bridge => nothing to propagate. */
1066 	if (!bridge_state)
1067 		return;
1068 
1069 	next_bridge = drm_bridge_get_next_bridge(bridge);
1070 
1071 	/*
1072 	 * Let's try to apply the most common case here, that is, propagate
1073 	 * display_info flags for the last bridge, and propagate the input
1074 	 * flags of the next bridge element to the output end of the current
1075 	 * bridge when the bridge is not the last one.
1076 	 * There are exceptions to this rule, like when signal inversion is
1077 	 * happening at the board level, but that's something drivers can deal
1078 	 * with from their &drm_bridge_funcs.atomic_check() implementation by
1079 	 * simply overriding the flags value we've set here.
1080 	 */
1081 	if (!next_bridge) {
1082 		output_flags = conn->display_info.bus_flags;
1083 	} else {
1084 		next_bridge_state = drm_atomic_get_new_bridge_state(state,
1085 								next_bridge);
1086 		/*
1087 		 * No bridge state attached to the next bridge, just leave the
1088 		 * flags to 0.
1089 		 */
1090 		if (next_bridge_state)
1091 			output_flags = next_bridge_state->input_bus_cfg.flags;
1092 	}
1093 
1094 	bridge_state->output_bus_cfg.flags = output_flags;
1095 
1096 	/*
1097 	 * Propagate the output flags to the input end of the bridge. Again, it's
1098 	 * not necessarily what all bridges want, but that's what most of them
1099 	 * do, and by doing that by default we avoid forcing drivers to
1100 	 * duplicate the "dummy propagation" logic.
1101 	 */
1102 	bridge_state->input_bus_cfg.flags = output_flags;
1103 }
1104 
1105 /**
1106  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1107  * @bridge: bridge control structure
1108  * @crtc_state: new CRTC state
1109  * @conn_state: new connector state
1110  *
1111  * First trigger a bus format negotiation before calling
1112  * &drm_bridge_funcs.atomic_check() (falls back on
1113  * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1114  * starting from the last bridge to the first. These are called before calling
1115  * &drm_encoder_helper_funcs.atomic_check()
1116  *
1117  * RETURNS:
1118  * 0 on success, a negative error code on failure
1119  */
drm_atomic_bridge_chain_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)1120 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1121 				  struct drm_crtc_state *crtc_state,
1122 				  struct drm_connector_state *conn_state)
1123 {
1124 	struct drm_connector *conn = conn_state->connector;
1125 	struct drm_encoder *encoder;
1126 	struct drm_bridge *iter;
1127 	int ret;
1128 
1129 	if (!bridge)
1130 		return 0;
1131 
1132 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1133 						      conn_state);
1134 	if (ret)
1135 		return ret;
1136 
1137 	encoder = bridge->encoder;
1138 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1139 		int ret;
1140 
1141 		/*
1142 		 * Bus flags are propagated by default. If a bridge needs to
1143 		 * tweak the input bus flags for any reason, it should happen
1144 		 * in its &drm_bridge_funcs.atomic_check() implementation such
1145 		 * that preceding bridges in the chain can propagate the new
1146 		 * bus flags.
1147 		 */
1148 		drm_atomic_bridge_propagate_bus_flags(iter, conn,
1149 						      crtc_state->state);
1150 
1151 		ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1152 		if (ret)
1153 			return ret;
1154 
1155 		if (iter == bridge)
1156 			break;
1157 	}
1158 
1159 	return 0;
1160 }
1161 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1162 
1163 /**
1164  * drm_bridge_detect - check if anything is attached to the bridge output
1165  * @bridge: bridge control structure
1166  *
1167  * If the bridge supports output detection, as reported by the
1168  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1169  * bridge and return the connection status. Otherwise return
1170  * connector_status_unknown.
1171  *
1172  * RETURNS:
1173  * The detection status on success, or connector_status_unknown if the bridge
1174  * doesn't support output detection.
1175  */
drm_bridge_detect(struct drm_bridge * bridge)1176 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1177 {
1178 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1179 		return connector_status_unknown;
1180 
1181 	return bridge->funcs->detect(bridge);
1182 }
1183 EXPORT_SYMBOL_GPL(drm_bridge_detect);
1184 
1185 /**
1186  * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1187  * @connector
1188  * @bridge: bridge control structure
1189  * @connector: the connector to fill with modes
1190  *
1191  * If the bridge supports output modes retrieval, as reported by the
1192  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1193  * fill the connector with all valid modes and return the number of modes
1194  * added. Otherwise return 0.
1195  *
1196  * RETURNS:
1197  * The number of modes added to the connector.
1198  */
drm_bridge_get_modes(struct drm_bridge * bridge,struct drm_connector * connector)1199 int drm_bridge_get_modes(struct drm_bridge *bridge,
1200 			 struct drm_connector *connector)
1201 {
1202 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1203 		return 0;
1204 
1205 	return bridge->funcs->get_modes(bridge, connector);
1206 }
1207 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1208 
1209 /**
1210  * drm_bridge_get_edid - get the EDID data of the connected display
1211  * @bridge: bridge control structure
1212  * @connector: the connector to read EDID for
1213  *
1214  * If the bridge supports output EDID retrieval, as reported by the
1215  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1216  * get the EDID and return it. Otherwise return NULL.
1217  *
1218  * RETURNS:
1219  * The retrieved EDID on success, or NULL otherwise.
1220  */
drm_bridge_get_edid(struct drm_bridge * bridge,struct drm_connector * connector)1221 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1222 				 struct drm_connector *connector)
1223 {
1224 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1225 		return NULL;
1226 
1227 	return bridge->funcs->get_edid(bridge, connector);
1228 }
1229 EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1230 
1231 /**
1232  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1233  * @bridge: bridge control structure
1234  * @cb: hot-plug detection callback
1235  * @data: data to be passed to the hot-plug detection callback
1236  *
1237  * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1238  * and @data as hot plug notification callback. From now on the @cb will be
1239  * called with @data when an output status change is detected by the bridge,
1240  * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1241  *
1242  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1243  * bridge->ops. This function shall not be called when the flag is not set.
1244  *
1245  * Only one hot plug detection callback can be registered at a time, it is an
1246  * error to call this function when hot plug detection is already enabled for
1247  * the bridge.
1248  */
drm_bridge_hpd_enable(struct drm_bridge * bridge,void (* cb)(void * data,enum drm_connector_status status),void * data)1249 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1250 			   void (*cb)(void *data,
1251 				      enum drm_connector_status status),
1252 			   void *data)
1253 {
1254 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1255 		return;
1256 
1257 	mutex_lock(&bridge->hpd_mutex);
1258 
1259 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1260 		goto unlock;
1261 
1262 	bridge->hpd_cb = cb;
1263 	bridge->hpd_data = data;
1264 
1265 	if (bridge->funcs->hpd_enable)
1266 		bridge->funcs->hpd_enable(bridge);
1267 
1268 unlock:
1269 	mutex_unlock(&bridge->hpd_mutex);
1270 }
1271 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1272 
1273 /**
1274  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1275  * @bridge: bridge control structure
1276  *
1277  * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1278  * plug detection callback previously registered with drm_bridge_hpd_enable().
1279  * Once this function returns the callback will not be called by the bridge
1280  * when an output status change occurs.
1281  *
1282  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1283  * bridge->ops. This function shall not be called when the flag is not set.
1284  */
drm_bridge_hpd_disable(struct drm_bridge * bridge)1285 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1286 {
1287 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1288 		return;
1289 
1290 	mutex_lock(&bridge->hpd_mutex);
1291 	if (bridge->funcs->hpd_disable)
1292 		bridge->funcs->hpd_disable(bridge);
1293 
1294 	bridge->hpd_cb = NULL;
1295 	bridge->hpd_data = NULL;
1296 	mutex_unlock(&bridge->hpd_mutex);
1297 }
1298 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1299 
1300 /**
1301  * drm_bridge_hpd_notify - notify hot plug detection events
1302  * @bridge: bridge control structure
1303  * @status: output connection status
1304  *
1305  * Bridge drivers shall call this function to report hot plug events when they
1306  * detect a change in the output status, when hot plug detection has been
1307  * enabled by drm_bridge_hpd_enable().
1308  *
1309  * This function shall be called in a context that can sleep.
1310  */
drm_bridge_hpd_notify(struct drm_bridge * bridge,enum drm_connector_status status)1311 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1312 			   enum drm_connector_status status)
1313 {
1314 	mutex_lock(&bridge->hpd_mutex);
1315 	if (bridge->hpd_cb)
1316 		bridge->hpd_cb(bridge->hpd_data, status);
1317 	mutex_unlock(&bridge->hpd_mutex);
1318 }
1319 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1320 
1321 #ifdef CONFIG_OF
1322 /**
1323  * of_drm_find_bridge - find the bridge corresponding to the device node in
1324  *			the global bridge list
1325  *
1326  * @np: device node
1327  *
1328  * RETURNS:
1329  * drm_bridge control struct on success, NULL on failure
1330  */
of_drm_find_bridge(struct device_node * np)1331 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1332 {
1333 	struct drm_bridge *bridge;
1334 
1335 	mutex_lock(&bridge_lock);
1336 
1337 	list_for_each_entry(bridge, &bridge_list, list) {
1338 		if (bridge->of_node == np) {
1339 			mutex_unlock(&bridge_lock);
1340 			return bridge;
1341 		}
1342 	}
1343 
1344 	mutex_unlock(&bridge_lock);
1345 	return NULL;
1346 }
1347 EXPORT_SYMBOL(of_drm_find_bridge);
1348 #endif
1349 
1350 #ifdef CONFIG_DEBUG_FS
drm_bridge_chains_info(struct seq_file * m,void * data)1351 static int drm_bridge_chains_info(struct seq_file *m, void *data)
1352 {
1353 	struct drm_debugfs_entry *entry = m->private;
1354 	struct drm_device *dev = entry->dev;
1355 	struct drm_printer p = drm_seq_file_printer(m);
1356 	struct drm_mode_config *config = &dev->mode_config;
1357 	struct drm_encoder *encoder;
1358 	unsigned int bridge_idx = 0;
1359 
1360 	list_for_each_entry(encoder, &config->encoder_list, head) {
1361 		struct drm_bridge *bridge;
1362 
1363 		drm_printf(&p, "encoder[%u]\n", encoder->base.id);
1364 
1365 		drm_for_each_bridge_in_chain(encoder, bridge) {
1366 			drm_printf(&p, "\tbridge[%u] type: %u, ops: %#x",
1367 				   bridge_idx, bridge->type, bridge->ops);
1368 
1369 #ifdef CONFIG_OF
1370 			if (bridge->of_node)
1371 				drm_printf(&p, ", OF: %pOFfc", bridge->of_node);
1372 #endif
1373 
1374 			drm_printf(&p, "\n");
1375 
1376 			bridge_idx++;
1377 		}
1378 	}
1379 
1380 	return 0;
1381 }
1382 
1383 static const struct drm_debugfs_info drm_bridge_debugfs_list[] = {
1384 	{ "bridge_chains", drm_bridge_chains_info, 0 },
1385 };
1386 
drm_bridge_debugfs_init(struct drm_minor * minor)1387 void drm_bridge_debugfs_init(struct drm_minor *minor)
1388 {
1389 	drm_debugfs_add_files(minor->dev, drm_bridge_debugfs_list,
1390 			      ARRAY_SIZE(drm_bridge_debugfs_list));
1391 }
1392 #endif
1393 
1394 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1395 MODULE_DESCRIPTION("DRM bridge infrastructure");
1396 MODULE_LICENSE("GPL and additional rights");
1397