1 /*
2  * Copyright (c) 2014 Samsung Electronics Co., Ltd
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sub license,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the
12  * next paragraph) shall be included in all copies or substantial portions
13  * of the Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21  * DEALINGS IN THE SOFTWARE.
22  */
23 
24 #include <linux/err.h>
25 #include <linux/media-bus-format.h>
26 #include <linux/module.h>
27 #include <linux/mutex.h>
28 
29 #include <drm/drm_atomic_state_helper.h>
30 #include <drm/drm_bridge.h>
31 #include <drm/drm_debugfs.h>
32 #include <drm/drm_edid.h>
33 #include <drm/drm_encoder.h>
34 #include <drm/drm_file.h>
35 #include <drm/drm_of.h>
36 #include <drm/drm_print.h>
37 
38 #include "drm_crtc_internal.h"
39 
40 /**
41  * DOC: overview
42  *
43  * &struct drm_bridge represents a device that hangs on to an encoder. These are
44  * handy when a regular &drm_encoder entity isn't enough to represent the entire
45  * encoder chain.
46  *
47  * A bridge is always attached to a single &drm_encoder at a time, but can be
48  * either connected to it directly, or through a chain of bridges::
49  *
50  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
51  *
52  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
53  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
54  * Chaining multiple bridges to the output of a bridge, or the same bridge to
55  * the output of different bridges, is not supported.
56  *
57  * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
58  * CRTCs, encoders or connectors and hence are not visible to userspace. They
59  * just provide additional hooks to get the desired output at the end of the
60  * encoder chain.
61  */
62 
63 /**
64  * DOC:	display driver integration
65  *
66  * Display drivers are responsible for linking encoders with the first bridge
67  * in the chains. This is done by acquiring the appropriate bridge with
68  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
69  * encoder with a call to drm_bridge_attach().
70  *
71  * Bridges are responsible for linking themselves with the next bridge in the
72  * chain, if any. This is done the same way as for encoders, with the call to
73  * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
74  *
75  * Once these links are created, the bridges can participate along with encoder
76  * functions to perform mode validation and fixup (through
77  * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
78  * setting (through drm_bridge_chain_mode_set()), enable (through
79  * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
80  * and disable (through drm_atomic_bridge_chain_disable() and
81  * drm_atomic_bridge_chain_post_disable()). Those functions call the
82  * corresponding operations provided in &drm_bridge_funcs in sequence for all
83  * bridges in the chain.
84  *
85  * For display drivers that use the atomic helpers
86  * drm_atomic_helper_check_modeset(),
87  * drm_atomic_helper_commit_modeset_enables() and
88  * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
89  * commit check and commit tail handlers, or through the higher-level
90  * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
91  * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
92  * requires no intervention from the driver. For other drivers, the relevant
93  * DRM bridge chain functions shall be called manually.
94  *
95  * Bridges also participate in implementing the &drm_connector at the end of
96  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
97  * helper to create the &drm_connector, or implement it manually on top of the
98  * connector-related operations exposed by the bridge (see the overview
99  * documentation of bridge operations for more details).
100  */
101 
102 /**
103  * DOC: special care dsi
104  *
105  * The interaction between the bridges and other frameworks involved in
106  * the probing of the upstream driver and the bridge driver can be
107  * challenging. Indeed, there's multiple cases that needs to be
108  * considered:
109  *
110  * - The upstream driver doesn't use the component framework and isn't a
111  *   MIPI-DSI host. In this case, the bridge driver will probe at some
112  *   point and the upstream driver should try to probe again by returning
113  *   EPROBE_DEFER as long as the bridge driver hasn't probed.
114  *
115  * - The upstream driver doesn't use the component framework, but is a
116  *   MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
117  *   controlled. In this case, the bridge device is a child of the
118  *   display device and when it will probe it's assured that the display
119  *   device (and MIPI-DSI host) is present. The upstream driver will be
120  *   assured that the bridge driver is connected between the
121  *   &mipi_dsi_host_ops.attach and &mipi_dsi_host_ops.detach operations.
122  *   Therefore, it must run mipi_dsi_host_register() in its probe
123  *   function, and then run drm_bridge_attach() in its
124  *   &mipi_dsi_host_ops.attach hook.
125  *
126  * - The upstream driver uses the component framework and is a MIPI-DSI
127  *   host. The bridge device uses the MIPI-DCS commands to be
128  *   controlled. This is the same situation than above, and can run
129  *   mipi_dsi_host_register() in either its probe or bind hooks.
130  *
131  * - The upstream driver uses the component framework and is a MIPI-DSI
132  *   host. The bridge device uses a separate bus (such as I2C) to be
133  *   controlled. In this case, there's no correlation between the probe
134  *   of the bridge and upstream drivers, so care must be taken to avoid
135  *   an endless EPROBE_DEFER loop, with each driver waiting for the
136  *   other to probe.
137  *
138  * The ideal pattern to cover the last item (and all the others in the
139  * MIPI-DSI host driver case) is to split the operations like this:
140  *
141  * - The MIPI-DSI host driver must run mipi_dsi_host_register() in its
142  *   probe hook. It will make sure that the MIPI-DSI host sticks around,
143  *   and that the driver's bind can be called.
144  *
145  * - In its probe hook, the bridge driver must try to find its MIPI-DSI
146  *   host, register as a MIPI-DSI device and attach the MIPI-DSI device
147  *   to its host. The bridge driver is now functional.
148  *
149  * - In its &struct mipi_dsi_host_ops.attach hook, the MIPI-DSI host can
150  *   now add its component. Its bind hook will now be called and since
151  *   the bridge driver is attached and registered, we can now look for
152  *   and attach it.
153  *
154  * At this point, we're now certain that both the upstream driver and
155  * the bridge driver are functional and we can't have a deadlock-like
156  * situation when probing.
157  */
158 
159 /**
160  * DOC: dsi bridge operations
161  *
162  * DSI host interfaces are expected to be implemented as bridges rather than
163  * encoders, however there are a few aspects of their operation that need to
164  * be defined in order to provide a consistent interface.
165  *
166  * A DSI host should keep the PHY powered down until the pre_enable operation is
167  * called. All lanes are in an undefined idle state up to this point, and it
168  * must not be assumed that it is LP-11.
169  * pre_enable should initialise the PHY, set the data lanes to LP-11, and the
170  * clock lane to either LP-11 or HS depending on the mode_flag
171  * %MIPI_DSI_CLOCK_NON_CONTINUOUS.
172  *
173  * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
174  * called before the DSI host. If the DSI peripheral requires LP-11 and/or
175  * the clock lane to be in HS mode prior to pre_enable, then it can set the
176  * &pre_enable_prev_first flag to request the pre_enable (and
177  * post_disable) order to be altered to enable the DSI host first.
178  *
179  * Either the CRTC being enabled, or the DSI host enable operation should switch
180  * the host to actively transmitting video on the data lanes.
181  *
182  * The reverse also applies. The DSI host disable operation or stopping the CRTC
183  * should stop transmitting video, and the data lanes should return to the LP-11
184  * state. The DSI host &post_disable operation should disable the PHY.
185  * If the &pre_enable_prev_first flag is set, then the DSI peripheral's
186  * bridge &post_disable will be called before the DSI host's post_disable.
187  *
188  * Whilst it is valid to call &host_transfer prior to pre_enable or after
189  * post_disable, the exact state of the lanes is undefined at this point. The
190  * DSI host should initialise the interface, transmit the data, and then disable
191  * the interface again.
192  *
193  * Ultra Low Power State (ULPS) is not explicitly supported by DRM. If
194  * implemented, it therefore needs to be handled entirely within the DSI Host
195  * driver.
196  */
197 
198 static DEFINE_MUTEX(bridge_lock);
199 static LIST_HEAD(bridge_list);
200 
201 /**
202  * drm_bridge_add - add the given bridge to the global bridge list
203  *
204  * @bridge: bridge control structure
205  */
drm_bridge_add(struct drm_bridge * bridge)206 void drm_bridge_add(struct drm_bridge *bridge)
207 {
208 	mutex_init(&bridge->hpd_mutex);
209 
210 	if (bridge->ops & DRM_BRIDGE_OP_HDMI)
211 		bridge->ycbcr_420_allowed = !!(bridge->supported_formats &
212 					       BIT(HDMI_COLORSPACE_YUV420));
213 
214 	mutex_lock(&bridge_lock);
215 	list_add_tail(&bridge->list, &bridge_list);
216 	mutex_unlock(&bridge_lock);
217 }
218 EXPORT_SYMBOL(drm_bridge_add);
219 
drm_bridge_remove_void(void * bridge)220 static void drm_bridge_remove_void(void *bridge)
221 {
222 	drm_bridge_remove(bridge);
223 }
224 
225 /**
226  * devm_drm_bridge_add - devm managed version of drm_bridge_add()
227  *
228  * @dev: device to tie the bridge lifetime to
229  * @bridge: bridge control structure
230  *
231  * This is the managed version of drm_bridge_add() which automatically
232  * calls drm_bridge_remove() when @dev is unbound.
233  *
234  * Return: 0 if no error or negative error code.
235  */
devm_drm_bridge_add(struct device * dev,struct drm_bridge * bridge)236 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
237 {
238 	drm_bridge_add(bridge);
239 	return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
240 }
241 EXPORT_SYMBOL(devm_drm_bridge_add);
242 
243 /**
244  * drm_bridge_remove - remove the given bridge from the global bridge list
245  *
246  * @bridge: bridge control structure
247  */
drm_bridge_remove(struct drm_bridge * bridge)248 void drm_bridge_remove(struct drm_bridge *bridge)
249 {
250 	mutex_lock(&bridge_lock);
251 	list_del_init(&bridge->list);
252 	mutex_unlock(&bridge_lock);
253 
254 	mutex_destroy(&bridge->hpd_mutex);
255 }
256 EXPORT_SYMBOL(drm_bridge_remove);
257 
258 static struct drm_private_state *
drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj * obj)259 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
260 {
261 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
262 	struct drm_bridge_state *state;
263 
264 	state = bridge->funcs->atomic_duplicate_state(bridge);
265 	return state ? &state->base : NULL;
266 }
267 
268 static void
drm_bridge_atomic_destroy_priv_state(struct drm_private_obj * obj,struct drm_private_state * s)269 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
270 				     struct drm_private_state *s)
271 {
272 	struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
273 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
274 
275 	bridge->funcs->atomic_destroy_state(bridge, state);
276 }
277 
278 static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
279 	.atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
280 	.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
281 };
282 
283 /**
284  * drm_bridge_attach - attach the bridge to an encoder's chain
285  *
286  * @encoder: DRM encoder
287  * @bridge: bridge to attach
288  * @previous: previous bridge in the chain (optional)
289  * @flags: DRM_BRIDGE_ATTACH_* flags
290  *
291  * Called by a kms driver to link the bridge to an encoder's chain. The previous
292  * argument specifies the previous bridge in the chain. If NULL, the bridge is
293  * linked directly at the encoder's output. Otherwise it is linked at the
294  * previous bridge's output.
295  *
296  * If non-NULL the previous bridge must be already attached by a call to this
297  * function.
298  *
299  * Note that bridges attached to encoders are auto-detached during encoder
300  * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
301  * *not* be balanced with a drm_bridge_detach() in driver code.
302  *
303  * RETURNS:
304  * Zero on success, error code on failure
305  */
drm_bridge_attach(struct drm_encoder * encoder,struct drm_bridge * bridge,struct drm_bridge * previous,enum drm_bridge_attach_flags flags)306 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
307 		      struct drm_bridge *previous,
308 		      enum drm_bridge_attach_flags flags)
309 {
310 	int ret;
311 
312 	if (!encoder || !bridge)
313 		return -EINVAL;
314 
315 	if (previous && (!previous->dev || previous->encoder != encoder))
316 		return -EINVAL;
317 
318 	if (bridge->dev)
319 		return -EBUSY;
320 
321 	bridge->dev = encoder->dev;
322 	bridge->encoder = encoder;
323 
324 	if (previous)
325 		list_add(&bridge->chain_node, &previous->chain_node);
326 	else
327 		list_add(&bridge->chain_node, &encoder->bridge_chain);
328 
329 	if (bridge->funcs->attach) {
330 		ret = bridge->funcs->attach(bridge, flags);
331 		if (ret < 0)
332 			goto err_reset_bridge;
333 	}
334 
335 	if (bridge->funcs->atomic_reset) {
336 		struct drm_bridge_state *state;
337 
338 		state = bridge->funcs->atomic_reset(bridge);
339 		if (IS_ERR(state)) {
340 			ret = PTR_ERR(state);
341 			goto err_detach_bridge;
342 		}
343 
344 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,
345 					    &state->base,
346 					    &drm_bridge_priv_state_funcs);
347 	}
348 
349 	return 0;
350 
351 err_detach_bridge:
352 	if (bridge->funcs->detach)
353 		bridge->funcs->detach(bridge);
354 
355 err_reset_bridge:
356 	bridge->dev = NULL;
357 	bridge->encoder = NULL;
358 	list_del(&bridge->chain_node);
359 
360 	if (ret != -EPROBE_DEFER)
361 		DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
362 			  bridge->of_node, encoder->name, ret);
363 	else
364 		dev_err_probe(encoder->dev->dev, -EPROBE_DEFER,
365 			      "failed to attach bridge %pOF to encoder %s\n",
366 			      bridge->of_node, encoder->name);
367 
368 	return ret;
369 }
370 EXPORT_SYMBOL(drm_bridge_attach);
371 
drm_bridge_detach(struct drm_bridge * bridge)372 void drm_bridge_detach(struct drm_bridge *bridge)
373 {
374 	if (WARN_ON(!bridge))
375 		return;
376 
377 	if (WARN_ON(!bridge->dev))
378 		return;
379 
380 	if (bridge->funcs->atomic_reset)
381 		drm_atomic_private_obj_fini(&bridge->base);
382 
383 	if (bridge->funcs->detach)
384 		bridge->funcs->detach(bridge);
385 
386 	list_del(&bridge->chain_node);
387 	bridge->dev = NULL;
388 }
389 
390 /**
391  * DOC: bridge operations
392  *
393  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
394  * The DRM internals (atomic and CRTC helpers) use the helpers defined in
395  * drm_bridge.c to call bridge operations. Those operations are divided in
396  * three big categories to support different parts of the bridge usage.
397  *
398  * - The encoder-related operations support control of the bridges in the
399  *   chain, and are roughly counterparts to the &drm_encoder_helper_funcs
400  *   operations. They are used by the legacy CRTC and the atomic modeset
401  *   helpers to perform mode validation, fixup and setting, and enable and
402  *   disable the bridge automatically.
403  *
404  *   The enable and disable operations are split in
405  *   &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
406  *   &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
407  *   finer-grained control.
408  *
409  *   Bridge drivers may implement the legacy version of those operations, or
410  *   the atomic version (prefixed with atomic\_), in which case they shall also
411  *   implement the atomic state bookkeeping operations
412  *   (&drm_bridge_funcs.atomic_duplicate_state,
413  *   &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
414  *   Mixing atomic and non-atomic versions of the operations is not supported.
415  *
416  * - The bus format negotiation operations
417  *   &drm_bridge_funcs.atomic_get_output_bus_fmts and
418  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
419  *   negotiate the formats transmitted between bridges in the chain when
420  *   multiple formats are supported. Negotiation for formats is performed
421  *   transparently for display drivers by the atomic modeset helpers. Only
422  *   atomic versions of those operations exist, bridge drivers that need to
423  *   implement them shall thus also implement the atomic version of the
424  *   encoder-related operations. This feature is not supported by the legacy
425  *   CRTC helpers.
426  *
427  * - The connector-related operations support implementing a &drm_connector
428  *   based on a chain of bridges. DRM bridges traditionally create a
429  *   &drm_connector for bridges meant to be used at the end of the chain. This
430  *   puts additional burden on bridge drivers, especially for bridges that may
431  *   be used in the middle of a chain or at the end of it. Furthermore, it
432  *   requires all operations of the &drm_connector to be handled by a single
433  *   bridge, which doesn't always match the hardware architecture.
434  *
435  *   To simplify bridge drivers and make the connector implementation more
436  *   flexible, a new model allows bridges to unconditionally skip creation of
437  *   &drm_connector and instead expose &drm_bridge_funcs operations to support
438  *   an externally-implemented &drm_connector. Those operations are
439  *   &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
440  *   &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
441  *   &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
442  *   implemented, display drivers shall create a &drm_connector instance for
443  *   each chain of bridges, and implement those connector instances based on
444  *   the bridge connector operations.
445  *
446  *   Bridge drivers shall implement the connector-related operations for all
447  *   the features that the bridge hardware support. For instance, if a bridge
448  *   supports reading EDID, the &drm_bridge_funcs.get_edid shall be
449  *   implemented. This however doesn't mean that the DDC lines are wired to the
450  *   bridge on a particular platform, as they could also be connected to an I2C
451  *   controller of the SoC. Support for the connector-related operations on the
452  *   running platform is reported through the &drm_bridge.ops flags. Bridge
453  *   drivers shall detect which operations they can support on the platform
454  *   (usually this information is provided by ACPI or DT), and set the
455  *   &drm_bridge.ops flags for all supported operations. A flag shall only be
456  *   set if the corresponding &drm_bridge_funcs operation is implemented, but
457  *   an implemented operation doesn't necessarily imply that the corresponding
458  *   flag will be set. Display drivers shall use the &drm_bridge.ops flags to
459  *   decide which bridge to delegate a connector operation to. This mechanism
460  *   allows providing a single static const &drm_bridge_funcs instance in
461  *   bridge drivers, improving security by storing function pointers in
462  *   read-only memory.
463  *
464  *   In order to ease transition, bridge drivers may support both the old and
465  *   new models by making connector creation optional and implementing the
466  *   connected-related bridge operations. Connector creation is then controlled
467  *   by the flags argument to the drm_bridge_attach() function. Display drivers
468  *   that support the new model and create connectors themselves shall set the
469  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
470  *   connector creation. For intermediate bridges in the chain, the flag shall
471  *   be passed to the drm_bridge_attach() call for the downstream bridge.
472  *   Bridge drivers that implement the new model only shall return an error
473  *   from their &drm_bridge_funcs.attach handler when the
474  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
475  *   should use the new model, and convert the bridge drivers they use if
476  *   needed, in order to gradually transition to the new model.
477  */
478 
479 /**
480  * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
481  *				 encoder chain.
482  * @bridge: bridge control structure
483  * @info: display info against which the mode shall be validated
484  * @mode: desired mode to be validated
485  *
486  * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
487  * chain, starting from the first bridge to the last. If at least one bridge
488  * does not accept the mode the function returns the error code.
489  *
490  * Note: the bridge passed should be the one closest to the encoder.
491  *
492  * RETURNS:
493  * MODE_OK on success, drm_mode_status Enum error code on failure
494  */
495 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)496 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
497 			    const struct drm_display_info *info,
498 			    const struct drm_display_mode *mode)
499 {
500 	struct drm_encoder *encoder;
501 
502 	if (!bridge)
503 		return MODE_OK;
504 
505 	encoder = bridge->encoder;
506 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
507 		enum drm_mode_status ret;
508 
509 		if (!bridge->funcs->mode_valid)
510 			continue;
511 
512 		ret = bridge->funcs->mode_valid(bridge, info, mode);
513 		if (ret != MODE_OK)
514 			return ret;
515 	}
516 
517 	return MODE_OK;
518 }
519 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
520 
521 /**
522  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
523  *			       encoder chain
524  * @bridge: bridge control structure
525  * @mode: desired mode to be set for the encoder chain
526  * @adjusted_mode: updated mode that works for this encoder chain
527  *
528  * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
529  * encoder chain, starting from the first bridge to the last.
530  *
531  * Note: the bridge passed should be the one closest to the encoder
532  */
drm_bridge_chain_mode_set(struct drm_bridge * bridge,const struct drm_display_mode * mode,const struct drm_display_mode * adjusted_mode)533 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
534 			       const struct drm_display_mode *mode,
535 			       const struct drm_display_mode *adjusted_mode)
536 {
537 	struct drm_encoder *encoder;
538 
539 	if (!bridge)
540 		return;
541 
542 	encoder = bridge->encoder;
543 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
544 		if (bridge->funcs->mode_set)
545 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);
546 	}
547 }
548 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
549 
550 /**
551  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
552  * @bridge: bridge control structure
553  * @state: atomic state being committed
554  *
555  * Calls &drm_bridge_funcs.atomic_disable (falls back on
556  * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
557  * starting from the last bridge to the first. These are called before calling
558  * &drm_encoder_helper_funcs.atomic_disable
559  *
560  * Note: the bridge passed should be the one closest to the encoder
561  */
drm_atomic_bridge_chain_disable(struct drm_bridge * bridge,struct drm_atomic_state * state)562 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
563 				     struct drm_atomic_state *state)
564 {
565 	struct drm_encoder *encoder;
566 	struct drm_bridge *iter;
567 
568 	if (!bridge)
569 		return;
570 
571 	encoder = bridge->encoder;
572 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
573 		if (iter->funcs->atomic_disable) {
574 			iter->funcs->atomic_disable(iter, state);
575 		} else if (iter->funcs->disable) {
576 			iter->funcs->disable(iter);
577 		}
578 
579 		if (iter == bridge)
580 			break;
581 	}
582 }
583 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
584 
drm_atomic_bridge_call_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * state)585 static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
586 						struct drm_atomic_state *state)
587 {
588 	if (state && bridge->funcs->atomic_post_disable)
589 		bridge->funcs->atomic_post_disable(bridge, state);
590 	else if (bridge->funcs->post_disable)
591 		bridge->funcs->post_disable(bridge);
592 }
593 
594 /**
595  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
596  *					  in the encoder chain
597  * @bridge: bridge control structure
598  * @state: atomic state being committed
599  *
600  * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
601  * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
602  * starting from the first bridge to the last. These are called after completing
603  * &drm_encoder_helper_funcs.atomic_disable
604  *
605  * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
606  * bridge will be called before the previous one to reverse the @pre_enable
607  * calling direction.
608  *
609  * Example:
610  * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
611  *
612  * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
613  * @post_disable order would be,
614  * Bridge B, Bridge A, Bridge E, Bridge D, Bridge C.
615  *
616  * Note: the bridge passed should be the one closest to the encoder
617  */
drm_atomic_bridge_chain_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * state)618 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
619 					  struct drm_atomic_state *state)
620 {
621 	struct drm_encoder *encoder;
622 	struct drm_bridge *next, *limit;
623 
624 	if (!bridge)
625 		return;
626 
627 	encoder = bridge->encoder;
628 
629 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
630 		limit = NULL;
631 
632 		if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
633 			next = list_next_entry(bridge, chain_node);
634 
635 			if (next->pre_enable_prev_first) {
636 				/* next bridge had requested that prev
637 				 * was enabled first, so disabled last
638 				 */
639 				limit = next;
640 
641 				/* Find the next bridge that has NOT requested
642 				 * prev to be enabled first / disabled last
643 				 */
644 				list_for_each_entry_from(next, &encoder->bridge_chain,
645 							 chain_node) {
646 					if (!next->pre_enable_prev_first) {
647 						next = list_prev_entry(next, chain_node);
648 						limit = next;
649 						break;
650 					}
651 
652 					if (list_is_last(&next->chain_node,
653 							 &encoder->bridge_chain)) {
654 						limit = next;
655 						break;
656 					}
657 				}
658 
659 				/* Call these bridges in reverse order */
660 				list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
661 								 chain_node) {
662 					if (next == bridge)
663 						break;
664 
665 					drm_atomic_bridge_call_post_disable(next,
666 									    state);
667 				}
668 			}
669 		}
670 
671 		drm_atomic_bridge_call_post_disable(bridge, state);
672 
673 		if (limit)
674 			/* Jump all bridges that we have already post_disabled */
675 			bridge = limit;
676 	}
677 }
678 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
679 
drm_atomic_bridge_call_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * state)680 static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
681 					      struct drm_atomic_state *state)
682 {
683 	if (state && bridge->funcs->atomic_pre_enable)
684 		bridge->funcs->atomic_pre_enable(bridge, state);
685 	else if (bridge->funcs->pre_enable)
686 		bridge->funcs->pre_enable(bridge);
687 }
688 
689 /**
690  * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
691  *					the encoder chain
692  * @bridge: bridge control structure
693  * @state: atomic state being committed
694  *
695  * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
696  * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
697  * starting from the last bridge to the first. These are called before calling
698  * &drm_encoder_helper_funcs.atomic_enable
699  *
700  * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
701  * prev bridge will be called before pre_enable of this bridge.
702  *
703  * Example:
704  * Bridge A ---> Bridge B ---> Bridge C ---> Bridge D ---> Bridge E
705  *
706  * With pre_enable_prev_first flag enable in Bridge B, D, E then the resulting
707  * @pre_enable order would be,
708  * Bridge C, Bridge D, Bridge E, Bridge A, Bridge B.
709  *
710  * Note: the bridge passed should be the one closest to the encoder
711  */
drm_atomic_bridge_chain_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * state)712 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
713 					struct drm_atomic_state *state)
714 {
715 	struct drm_encoder *encoder;
716 	struct drm_bridge *iter, *next, *limit;
717 
718 	if (!bridge)
719 		return;
720 
721 	encoder = bridge->encoder;
722 
723 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
724 		if (iter->pre_enable_prev_first) {
725 			next = iter;
726 			limit = bridge;
727 			list_for_each_entry_from_reverse(next,
728 							 &encoder->bridge_chain,
729 							 chain_node) {
730 				if (next == bridge)
731 					break;
732 
733 				if (!next->pre_enable_prev_first) {
734 					/* Found first bridge that does NOT
735 					 * request prev to be enabled first
736 					 */
737 					limit = next;
738 					break;
739 				}
740 			}
741 
742 			list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
743 				/* Call requested prev bridge pre_enable
744 				 * in order.
745 				 */
746 				if (next == iter)
747 					/* At the first bridge to request prev
748 					 * bridges called first.
749 					 */
750 					break;
751 
752 				drm_atomic_bridge_call_pre_enable(next, state);
753 			}
754 		}
755 
756 		drm_atomic_bridge_call_pre_enable(iter, state);
757 
758 		if (iter->pre_enable_prev_first)
759 			/* Jump all bridges that we have already pre_enabled */
760 			iter = limit;
761 
762 		if (iter == bridge)
763 			break;
764 	}
765 }
766 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
767 
768 /**
769  * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
770  * @bridge: bridge control structure
771  * @state: atomic state being committed
772  *
773  * Calls &drm_bridge_funcs.atomic_enable (falls back on
774  * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
775  * starting from the first bridge to the last. These are called after completing
776  * &drm_encoder_helper_funcs.atomic_enable
777  *
778  * Note: the bridge passed should be the one closest to the encoder
779  */
drm_atomic_bridge_chain_enable(struct drm_bridge * bridge,struct drm_atomic_state * state)780 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
781 				    struct drm_atomic_state *state)
782 {
783 	struct drm_encoder *encoder;
784 
785 	if (!bridge)
786 		return;
787 
788 	encoder = bridge->encoder;
789 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
790 		if (bridge->funcs->atomic_enable) {
791 			bridge->funcs->atomic_enable(bridge, state);
792 		} else if (bridge->funcs->enable) {
793 			bridge->funcs->enable(bridge);
794 		}
795 	}
796 }
797 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
798 
drm_atomic_bridge_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)799 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
800 				   struct drm_crtc_state *crtc_state,
801 				   struct drm_connector_state *conn_state)
802 {
803 	if (bridge->funcs->atomic_check) {
804 		struct drm_bridge_state *bridge_state;
805 		int ret;
806 
807 		bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
808 							       bridge);
809 		if (WARN_ON(!bridge_state))
810 			return -EINVAL;
811 
812 		ret = bridge->funcs->atomic_check(bridge, bridge_state,
813 						  crtc_state, conn_state);
814 		if (ret)
815 			return ret;
816 	} else if (bridge->funcs->mode_fixup) {
817 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
818 					       &crtc_state->adjusted_mode))
819 			return -EINVAL;
820 	}
821 
822 	return 0;
823 }
824 
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)825 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
826 				    struct drm_bridge *cur_bridge,
827 				    struct drm_crtc_state *crtc_state,
828 				    struct drm_connector_state *conn_state,
829 				    u32 out_bus_fmt)
830 {
831 	unsigned int i, num_in_bus_fmts = 0;
832 	struct drm_bridge_state *cur_state;
833 	struct drm_bridge *prev_bridge;
834 	u32 *in_bus_fmts;
835 	int ret;
836 
837 	prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
838 	cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
839 						    cur_bridge);
840 
841 	/*
842 	 * If bus format negotiation is not supported by this bridge, let's
843 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
844 	 * hope that it can handle this situation gracefully (by providing
845 	 * appropriate default values).
846 	 */
847 	if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
848 		if (cur_bridge != first_bridge) {
849 			ret = select_bus_fmt_recursive(first_bridge,
850 						       prev_bridge, crtc_state,
851 						       conn_state,
852 						       MEDIA_BUS_FMT_FIXED);
853 			if (ret)
854 				return ret;
855 		}
856 
857 		/*
858 		 * Driver does not implement the atomic state hooks, but that's
859 		 * fine, as long as it does not access the bridge state.
860 		 */
861 		if (cur_state) {
862 			cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
863 			cur_state->output_bus_cfg.format = out_bus_fmt;
864 		}
865 
866 		return 0;
867 	}
868 
869 	/*
870 	 * If the driver implements ->atomic_get_input_bus_fmts() it
871 	 * should also implement the atomic state hooks.
872 	 */
873 	if (WARN_ON(!cur_state))
874 		return -EINVAL;
875 
876 	in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
877 							cur_state,
878 							crtc_state,
879 							conn_state,
880 							out_bus_fmt,
881 							&num_in_bus_fmts);
882 	if (!num_in_bus_fmts)
883 		return -ENOTSUPP;
884 	else if (!in_bus_fmts)
885 		return -ENOMEM;
886 
887 	if (first_bridge == cur_bridge) {
888 		cur_state->input_bus_cfg.format = in_bus_fmts[0];
889 		cur_state->output_bus_cfg.format = out_bus_fmt;
890 		kfree(in_bus_fmts);
891 		return 0;
892 	}
893 
894 	for (i = 0; i < num_in_bus_fmts; i++) {
895 		ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
896 					       crtc_state, conn_state,
897 					       in_bus_fmts[i]);
898 		if (ret != -ENOTSUPP)
899 			break;
900 	}
901 
902 	if (!ret) {
903 		cur_state->input_bus_cfg.format = in_bus_fmts[i];
904 		cur_state->output_bus_cfg.format = out_bus_fmt;
905 	}
906 
907 	kfree(in_bus_fmts);
908 	return ret;
909 }
910 
911 /*
912  * This function is called by &drm_atomic_bridge_chain_check() just before
913  * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
914  * It performs bus format negotiation between bridge elements. The negotiation
915  * happens in reverse order, starting from the last element in the chain up to
916  * @bridge.
917  *
918  * Negotiation starts by retrieving supported output bus formats on the last
919  * bridge element and testing them one by one. The test is recursive, meaning
920  * that for each tested output format, the whole chain will be walked backward,
921  * and each element will have to choose an input bus format that can be
922  * transcoded to the requested output format. When a bridge element does not
923  * support transcoding into a specific output format -ENOTSUPP is returned and
924  * the next bridge element will have to try a different format. If none of the
925  * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
926  *
927  * This implementation is relying on
928  * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
929  * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
930  * input/output formats.
931  *
932  * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
933  * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
934  * tries a single format: &drm_connector.display_info.bus_formats[0] if
935  * available, MEDIA_BUS_FMT_FIXED otherwise.
936  *
937  * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
938  * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
939  * bridge element that lacks this hook and asks the previous element in the
940  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
941  * to do in that case (fail if they want to enforce bus format negotiation, or
942  * provide a reasonable default if they need to support pipelines where not
943  * all elements support bus format negotiation).
944  */
945 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)946 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
947 					struct drm_crtc_state *crtc_state,
948 					struct drm_connector_state *conn_state)
949 {
950 	struct drm_connector *conn = conn_state->connector;
951 	struct drm_encoder *encoder = bridge->encoder;
952 	struct drm_bridge_state *last_bridge_state;
953 	unsigned int i, num_out_bus_fmts = 0;
954 	struct drm_bridge *last_bridge;
955 	u32 *out_bus_fmts;
956 	int ret = 0;
957 
958 	last_bridge = list_last_entry(&encoder->bridge_chain,
959 				      struct drm_bridge, chain_node);
960 	last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
961 							    last_bridge);
962 
963 	if (last_bridge->funcs->atomic_get_output_bus_fmts) {
964 		const struct drm_bridge_funcs *funcs = last_bridge->funcs;
965 
966 		/*
967 		 * If the driver implements ->atomic_get_output_bus_fmts() it
968 		 * should also implement the atomic state hooks.
969 		 */
970 		if (WARN_ON(!last_bridge_state))
971 			return -EINVAL;
972 
973 		out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
974 							last_bridge_state,
975 							crtc_state,
976 							conn_state,
977 							&num_out_bus_fmts);
978 		if (!num_out_bus_fmts)
979 			return -ENOTSUPP;
980 		else if (!out_bus_fmts)
981 			return -ENOMEM;
982 	} else {
983 		num_out_bus_fmts = 1;
984 		out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
985 		if (!out_bus_fmts)
986 			return -ENOMEM;
987 
988 		if (conn->display_info.num_bus_formats &&
989 		    conn->display_info.bus_formats)
990 			out_bus_fmts[0] = conn->display_info.bus_formats[0];
991 		else
992 			out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
993 	}
994 
995 	for (i = 0; i < num_out_bus_fmts; i++) {
996 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
997 					       conn_state, out_bus_fmts[i]);
998 		if (ret != -ENOTSUPP)
999 			break;
1000 	}
1001 
1002 	kfree(out_bus_fmts);
1003 
1004 	return ret;
1005 }
1006 
1007 static void
drm_atomic_bridge_propagate_bus_flags(struct drm_bridge * bridge,struct drm_connector * conn,struct drm_atomic_state * state)1008 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
1009 				      struct drm_connector *conn,
1010 				      struct drm_atomic_state *state)
1011 {
1012 	struct drm_bridge_state *bridge_state, *next_bridge_state;
1013 	struct drm_bridge *next_bridge;
1014 	u32 output_flags = 0;
1015 
1016 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
1017 
1018 	/* No bridge state attached to this bridge => nothing to propagate. */
1019 	if (!bridge_state)
1020 		return;
1021 
1022 	next_bridge = drm_bridge_get_next_bridge(bridge);
1023 
1024 	/*
1025 	 * Let's try to apply the most common case here, that is, propagate
1026 	 * display_info flags for the last bridge, and propagate the input
1027 	 * flags of the next bridge element to the output end of the current
1028 	 * bridge when the bridge is not the last one.
1029 	 * There are exceptions to this rule, like when signal inversion is
1030 	 * happening at the board level, but that's something drivers can deal
1031 	 * with from their &drm_bridge_funcs.atomic_check() implementation by
1032 	 * simply overriding the flags value we've set here.
1033 	 */
1034 	if (!next_bridge) {
1035 		output_flags = conn->display_info.bus_flags;
1036 	} else {
1037 		next_bridge_state = drm_atomic_get_new_bridge_state(state,
1038 								next_bridge);
1039 		/*
1040 		 * No bridge state attached to the next bridge, just leave the
1041 		 * flags to 0.
1042 		 */
1043 		if (next_bridge_state)
1044 			output_flags = next_bridge_state->input_bus_cfg.flags;
1045 	}
1046 
1047 	bridge_state->output_bus_cfg.flags = output_flags;
1048 
1049 	/*
1050 	 * Propagate the output flags to the input end of the bridge. Again, it's
1051 	 * not necessarily what all bridges want, but that's what most of them
1052 	 * do, and by doing that by default we avoid forcing drivers to
1053 	 * duplicate the "dummy propagation" logic.
1054 	 */
1055 	bridge_state->input_bus_cfg.flags = output_flags;
1056 }
1057 
1058 /**
1059  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1060  * @bridge: bridge control structure
1061  * @crtc_state: new CRTC state
1062  * @conn_state: new connector state
1063  *
1064  * First trigger a bus format negotiation before calling
1065  * &drm_bridge_funcs.atomic_check() (falls back on
1066  * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1067  * starting from the last bridge to the first. These are called before calling
1068  * &drm_encoder_helper_funcs.atomic_check()
1069  *
1070  * RETURNS:
1071  * 0 on success, a negative error code on failure
1072  */
drm_atomic_bridge_chain_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)1073 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1074 				  struct drm_crtc_state *crtc_state,
1075 				  struct drm_connector_state *conn_state)
1076 {
1077 	struct drm_connector *conn = conn_state->connector;
1078 	struct drm_encoder *encoder;
1079 	struct drm_bridge *iter;
1080 	int ret;
1081 
1082 	if (!bridge)
1083 		return 0;
1084 
1085 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1086 						      conn_state);
1087 	if (ret)
1088 		return ret;
1089 
1090 	encoder = bridge->encoder;
1091 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1092 		int ret;
1093 
1094 		/*
1095 		 * Bus flags are propagated by default. If a bridge needs to
1096 		 * tweak the input bus flags for any reason, it should happen
1097 		 * in its &drm_bridge_funcs.atomic_check() implementation such
1098 		 * that preceding bridges in the chain can propagate the new
1099 		 * bus flags.
1100 		 */
1101 		drm_atomic_bridge_propagate_bus_flags(iter, conn,
1102 						      crtc_state->state);
1103 
1104 		ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1105 		if (ret)
1106 			return ret;
1107 
1108 		if (iter == bridge)
1109 			break;
1110 	}
1111 
1112 	return 0;
1113 }
1114 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1115 
1116 /**
1117  * drm_bridge_detect - check if anything is attached to the bridge output
1118  * @bridge: bridge control structure
1119  *
1120  * If the bridge supports output detection, as reported by the
1121  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1122  * bridge and return the connection status. Otherwise return
1123  * connector_status_unknown.
1124  *
1125  * RETURNS:
1126  * The detection status on success, or connector_status_unknown if the bridge
1127  * doesn't support output detection.
1128  */
drm_bridge_detect(struct drm_bridge * bridge)1129 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1130 {
1131 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1132 		return connector_status_unknown;
1133 
1134 	return bridge->funcs->detect(bridge);
1135 }
1136 EXPORT_SYMBOL_GPL(drm_bridge_detect);
1137 
1138 /**
1139  * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1140  * @connector
1141  * @bridge: bridge control structure
1142  * @connector: the connector to fill with modes
1143  *
1144  * If the bridge supports output modes retrieval, as reported by the
1145  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1146  * fill the connector with all valid modes and return the number of modes
1147  * added. Otherwise return 0.
1148  *
1149  * RETURNS:
1150  * The number of modes added to the connector.
1151  */
drm_bridge_get_modes(struct drm_bridge * bridge,struct drm_connector * connector)1152 int drm_bridge_get_modes(struct drm_bridge *bridge,
1153 			 struct drm_connector *connector)
1154 {
1155 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1156 		return 0;
1157 
1158 	return bridge->funcs->get_modes(bridge, connector);
1159 }
1160 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1161 
1162 /**
1163  * drm_bridge_edid_read - read the EDID data of the connected display
1164  * @bridge: bridge control structure
1165  * @connector: the connector to read EDID for
1166  *
1167  * If the bridge supports output EDID retrieval, as reported by the
1168  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.edid_read to get
1169  * the EDID and return it. Otherwise return NULL.
1170  *
1171  * RETURNS:
1172  * The retrieved EDID on success, or NULL otherwise.
1173  */
drm_bridge_edid_read(struct drm_bridge * bridge,struct drm_connector * connector)1174 const struct drm_edid *drm_bridge_edid_read(struct drm_bridge *bridge,
1175 					    struct drm_connector *connector)
1176 {
1177 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1178 		return NULL;
1179 
1180 	return bridge->funcs->edid_read(bridge, connector);
1181 }
1182 EXPORT_SYMBOL_GPL(drm_bridge_edid_read);
1183 
1184 /**
1185  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1186  * @bridge: bridge control structure
1187  * @cb: hot-plug detection callback
1188  * @data: data to be passed to the hot-plug detection callback
1189  *
1190  * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1191  * and @data as hot plug notification callback. From now on the @cb will be
1192  * called with @data when an output status change is detected by the bridge,
1193  * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1194  *
1195  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1196  * bridge->ops. This function shall not be called when the flag is not set.
1197  *
1198  * Only one hot plug detection callback can be registered at a time, it is an
1199  * error to call this function when hot plug detection is already enabled for
1200  * the bridge.
1201  */
drm_bridge_hpd_enable(struct drm_bridge * bridge,void (* cb)(void * data,enum drm_connector_status status),void * data)1202 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1203 			   void (*cb)(void *data,
1204 				      enum drm_connector_status status),
1205 			   void *data)
1206 {
1207 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1208 		return;
1209 
1210 	mutex_lock(&bridge->hpd_mutex);
1211 
1212 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1213 		goto unlock;
1214 
1215 	bridge->hpd_cb = cb;
1216 	bridge->hpd_data = data;
1217 
1218 	if (bridge->funcs->hpd_enable)
1219 		bridge->funcs->hpd_enable(bridge);
1220 
1221 unlock:
1222 	mutex_unlock(&bridge->hpd_mutex);
1223 }
1224 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1225 
1226 /**
1227  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1228  * @bridge: bridge control structure
1229  *
1230  * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1231  * plug detection callback previously registered with drm_bridge_hpd_enable().
1232  * Once this function returns the callback will not be called by the bridge
1233  * when an output status change occurs.
1234  *
1235  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1236  * bridge->ops. This function shall not be called when the flag is not set.
1237  */
drm_bridge_hpd_disable(struct drm_bridge * bridge)1238 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1239 {
1240 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1241 		return;
1242 
1243 	mutex_lock(&bridge->hpd_mutex);
1244 	if (bridge->funcs->hpd_disable)
1245 		bridge->funcs->hpd_disable(bridge);
1246 
1247 	bridge->hpd_cb = NULL;
1248 	bridge->hpd_data = NULL;
1249 	mutex_unlock(&bridge->hpd_mutex);
1250 }
1251 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1252 
1253 /**
1254  * drm_bridge_hpd_notify - notify hot plug detection events
1255  * @bridge: bridge control structure
1256  * @status: output connection status
1257  *
1258  * Bridge drivers shall call this function to report hot plug events when they
1259  * detect a change in the output status, when hot plug detection has been
1260  * enabled by drm_bridge_hpd_enable().
1261  *
1262  * This function shall be called in a context that can sleep.
1263  */
drm_bridge_hpd_notify(struct drm_bridge * bridge,enum drm_connector_status status)1264 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1265 			   enum drm_connector_status status)
1266 {
1267 	mutex_lock(&bridge->hpd_mutex);
1268 	if (bridge->hpd_cb)
1269 		bridge->hpd_cb(bridge->hpd_data, status);
1270 	mutex_unlock(&bridge->hpd_mutex);
1271 }
1272 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1273 
1274 #ifdef CONFIG_OF
1275 /**
1276  * of_drm_find_bridge - find the bridge corresponding to the device node in
1277  *			the global bridge list
1278  *
1279  * @np: device node
1280  *
1281  * RETURNS:
1282  * drm_bridge control struct on success, NULL on failure
1283  */
of_drm_find_bridge(struct device_node * np)1284 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1285 {
1286 	struct drm_bridge *bridge;
1287 
1288 	mutex_lock(&bridge_lock);
1289 
1290 	list_for_each_entry(bridge, &bridge_list, list) {
1291 		if (bridge->of_node == np) {
1292 			mutex_unlock(&bridge_lock);
1293 			return bridge;
1294 		}
1295 	}
1296 
1297 	mutex_unlock(&bridge_lock);
1298 	return NULL;
1299 }
1300 EXPORT_SYMBOL(of_drm_find_bridge);
1301 #endif
1302 
1303 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1304 MODULE_DESCRIPTION("DRM bridge infrastructure");
1305 MODULE_LICENSE("GPL and additional rights");
1306