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