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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
27#include <drm/drm_crtc.h>
28
29#include "drm/drmP.h"
30
31/**
32 * DOC: overview
33 *
34 * struct &drm_bridge represents a device that hangs on to an encoder. These are
35 * handy when a regular &drm_encoder entity isn't enough to represent the entire
36 * encoder chain.
37 *
38 * A bridge is always attached to a single &drm_encoder at a time, but can be
39 * either connected to it directly, or through an intermediate bridge:
40 *
41 * encoder ---> bridge B ---> bridge A
42 *
43 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to
44 * bridge A.
45 *
46 * The driver using the bridge is responsible to make the associations between
47 * the encoder and bridges. Once these links are made, the bridges will
48 * participate along with encoder functions to perform mode_set/enable/disable
49 * through the ops provided in &drm_bridge_funcs.
50 *
51 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes,
52 * CRTCs, encoders or connectors and hence are not visible to userspace. They
53 * just provide additional hooks to get the desired output at the end of the
54 * encoder chain.
55 *
56 * Bridges can also be chained up using the next pointer in struct &drm_bridge.
57 *
58 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges.
59 */
60
61static DEFINE_MUTEX(bridge_lock);
62static LIST_HEAD(bridge_list);
63
64/**
65 * drm_bridge_add - add the given bridge to the global bridge list
66 *
67 * @bridge: bridge control structure
68 *
69 * RETURNS:
70 * Unconditionally returns Zero.
71 */
72int drm_bridge_add(struct drm_bridge *bridge)
73{
74 mutex_lock(&bridge_lock);
75 list_add_tail(&bridge->list, &bridge_list);
76 mutex_unlock(&bridge_lock);
77
78 return 0;
79}
80EXPORT_SYMBOL(drm_bridge_add);
81
82/**
83 * drm_bridge_remove - remove the given bridge from the global bridge list
84 *
85 * @bridge: bridge control structure
86 */
87void drm_bridge_remove(struct drm_bridge *bridge)
88{
89 mutex_lock(&bridge_lock);
90 list_del_init(&bridge->list);
91 mutex_unlock(&bridge_lock);
92}
93EXPORT_SYMBOL(drm_bridge_remove);
94
95/**
96 * drm_bridge_attach - associate given bridge to our DRM device
97 *
98 * @dev: DRM device
99 * @bridge: bridge control structure
100 *
101 * called by a kms driver to link one of our encoder/bridge to the given
102 * bridge.
103 *
104 * Note that setting up links between the bridge and our encoder/bridge
105 * objects needs to be handled by the kms driver itself
106 *
107 * RETURNS:
108 * Zero on success, error code on failure
109 */
110int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
111{
112 if (!dev || !bridge)
113 return -EINVAL;
114
115 if (bridge->dev)
116 return -EBUSY;
117
118 bridge->dev = dev;
119
120 if (bridge->funcs->attach)
121 return bridge->funcs->attach(bridge);
122
123 return 0;
124}
125EXPORT_SYMBOL(drm_bridge_attach);
126
127/**
128 * DOC: bridge callbacks
129 *
130 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
131 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c
132 * These helpers call a specific &drm_bridge_funcs op for all the bridges
133 * during encoder configuration.
134 *
135 * For detailed specification of the bridge callbacks see &drm_bridge_funcs.
136 */
137
138/**
139 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
140 * encoder chain
141 * @bridge: bridge control structure
142 * @mode: desired mode to be set for the bridge
143 * @adjusted_mode: updated mode that works for this bridge
144 *
145 * Calls ->mode_fixup() &drm_bridge_funcs op for all the bridges in the
146 * encoder chain, starting from the first bridge to the last.
147 *
148 * Note: the bridge passed should be the one closest to the encoder
149 *
150 * RETURNS:
151 * true on success, false on failure
152 */
153bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
154 const struct drm_display_mode *mode,
155 struct drm_display_mode *adjusted_mode)
156{
157 bool ret = true;
158
159 if (!bridge)
160 return true;
161
162 if (bridge->funcs->mode_fixup)
163 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
164
165 ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
166
167 return ret;
168}
169EXPORT_SYMBOL(drm_bridge_mode_fixup);
170
171/**
172 * drm_bridge_disable - calls ->disable() &drm_bridge_funcs op for all
173 * bridges in the encoder chain.
174 * @bridge: bridge control structure
175 *
176 * Calls ->disable() &drm_bridge_funcs op for all the bridges in the encoder
177 * chain, starting from the last bridge to the first. These are called before
178 * calling the encoder's prepare op.
179 *
180 * Note: the bridge passed should be the one closest to the encoder
181 */
182void drm_bridge_disable(struct drm_bridge *bridge)
183{
184 if (!bridge)
185 return;
186
187 drm_bridge_disable(bridge->next);
188
189 if (bridge->funcs->disable)
190 bridge->funcs->disable(bridge);
191}
192EXPORT_SYMBOL(drm_bridge_disable);
193
194/**
195 * drm_bridge_post_disable - calls ->post_disable() &drm_bridge_funcs op for
196 * all bridges in the encoder chain.
197 * @bridge: bridge control structure
198 *
199 * Calls ->post_disable() &drm_bridge_funcs op for all the bridges in the
200 * encoder chain, starting from the first bridge to the last. These are called
201 * after completing the encoder's prepare op.
202 *
203 * Note: the bridge passed should be the one closest to the encoder
204 */
205void drm_bridge_post_disable(struct drm_bridge *bridge)
206{
207 if (!bridge)
208 return;
209
210 if (bridge->funcs->post_disable)
211 bridge->funcs->post_disable(bridge);
212
213 drm_bridge_post_disable(bridge->next);
214}
215EXPORT_SYMBOL(drm_bridge_post_disable);
216
217/**
218 * drm_bridge_mode_set - set proposed mode for all bridges in the
219 * encoder chain
220 * @bridge: bridge control structure
221 * @mode: desired mode to be set for the bridge
222 * @adjusted_mode: updated mode that works for this bridge
223 *
224 * Calls ->mode_set() &drm_bridge_funcs op for all the bridges in the
225 * encoder chain, starting from the first bridge to the last.
226 *
227 * Note: the bridge passed should be the one closest to the encoder
228 */
229void drm_bridge_mode_set(struct drm_bridge *bridge,
230 struct drm_display_mode *mode,
231 struct drm_display_mode *adjusted_mode)
232{
233 if (!bridge)
234 return;
235
236 if (bridge->funcs->mode_set)
237 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
238
239 drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
240}
241EXPORT_SYMBOL(drm_bridge_mode_set);
242
243/**
244 * drm_bridge_pre_enable - calls ->pre_enable() &drm_bridge_funcs op for all
245 * bridges in the encoder chain.
246 * @bridge: bridge control structure
247 *
248 * Calls ->pre_enable() &drm_bridge_funcs op for all the bridges in the encoder
249 * chain, starting from the last bridge to the first. These are called
250 * before calling the encoder's commit op.
251 *
252 * Note: the bridge passed should be the one closest to the encoder
253 */
254void drm_bridge_pre_enable(struct drm_bridge *bridge)
255{
256 if (!bridge)
257 return;
258
259 drm_bridge_pre_enable(bridge->next);
260
261 if (bridge->funcs->pre_enable)
262 bridge->funcs->pre_enable(bridge);
263}
264EXPORT_SYMBOL(drm_bridge_pre_enable);
265
266/**
267 * drm_bridge_enable - calls ->enable() &drm_bridge_funcs op for all bridges
268 * in the encoder chain.
269 * @bridge: bridge control structure
270 *
271 * Calls ->enable() &drm_bridge_funcs op for all the bridges in the encoder
272 * chain, starting from the first bridge to the last. These are called
273 * after completing the encoder's commit op.
274 *
275 * Note that the bridge passed should be the one closest to the encoder
276 */
277void drm_bridge_enable(struct drm_bridge *bridge)
278{
279 if (!bridge)
280 return;
281
282 if (bridge->funcs->enable)
283 bridge->funcs->enable(bridge);
284
285 drm_bridge_enable(bridge->next);
286}
287EXPORT_SYMBOL(drm_bridge_enable);
288
289#ifdef CONFIG_OF
290/**
291 * of_drm_find_bridge - find the bridge corresponding to the device node in
292 * the global bridge list
293 *
294 * @np: device node
295 *
296 * RETURNS:
297 * drm_bridge control struct on success, NULL on failure
298 */
299struct drm_bridge *of_drm_find_bridge(struct device_node *np)
300{
301 struct drm_bridge *bridge;
302
303 mutex_lock(&bridge_lock);
304
305 list_for_each_entry(bridge, &bridge_list, list) {
306 if (bridge->of_node == np) {
307 mutex_unlock(&bridge_lock);
308 return bridge;
309 }
310 }
311
312 mutex_unlock(&bridge_lock);
313 return NULL;
314}
315EXPORT_SYMBOL(of_drm_find_bridge);
316#endif
317
318MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
319MODULE_DESCRIPTION("DRM bridge infrastructure");
320MODULE_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/media-bus-format.h>
26#include <linux/module.h>
27#include <linux/mutex.h>
28
29#include <drm/drm_atomic_state_helper.h>
30#include <drm/drm_debugfs.h>
31#include <drm/drm_bridge.h>
32#include <drm/drm_encoder.h>
33#include <drm/drm_file.h>
34#include <drm/drm_of.h>
35#include <drm/drm_print.h>
36
37#include "drm_crtc_internal.h"
38
39/**
40 * DOC: overview
41 *
42 * &struct drm_bridge represents a device that hangs on to an encoder. These are
43 * handy when a regular &drm_encoder entity isn't enough to represent the entire
44 * encoder chain.
45 *
46 * A bridge is always attached to a single &drm_encoder at a time, but can be
47 * either connected to it directly, or through a chain of bridges::
48 *
49 * [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
50 *
51 * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
52 * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
53 * Chaining multiple bridges to the output of a bridge, or the same bridge to
54 * the output of different bridges, is not supported.
55 *
56 * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
57 * CRTCs, encoders or connectors and hence are not visible to userspace. They
58 * just provide additional hooks to get the desired output at the end of the
59 * encoder chain.
60 */
61
62/**
63 * DOC: display driver integration
64 *
65 * Display drivers are responsible for linking encoders with the first bridge
66 * in the chains. This is done by acquiring the appropriate bridge with
67 * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
68 * encoder with a call to drm_bridge_attach().
69 *
70 * Bridges are responsible for linking themselves with the next bridge in the
71 * chain, if any. This is done the same way as for encoders, with the call to
72 * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
73 *
74 * Once these links are created, the bridges can participate along with encoder
75 * functions to perform mode validation and fixup (through
76 * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
77 * setting (through drm_bridge_chain_mode_set()), enable (through
78 * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
79 * and disable (through drm_atomic_bridge_chain_disable() and
80 * drm_atomic_bridge_chain_post_disable()). Those functions call the
81 * corresponding operations provided in &drm_bridge_funcs in sequence for all
82 * bridges in the chain.
83 *
84 * For display drivers that use the atomic helpers
85 * drm_atomic_helper_check_modeset(),
86 * drm_atomic_helper_commit_modeset_enables() and
87 * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
88 * commit check and commit tail handlers, or through the higher-level
89 * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
90 * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
91 * requires no intervention from the driver. For other drivers, the relevant
92 * DRM bridge chain functions shall be called manually.
93 *
94 * Bridges also participate in implementing the &drm_connector at the end of
95 * the bridge chain. Display drivers may use the drm_bridge_connector_init()
96 * helper to create the &drm_connector, or implement it manually on top of the
97 * connector-related operations exposed by the bridge (see the overview
98 * documentation of bridge operations for more details).
99 */
100
101/**
102 * DOC: special care dsi
103 *
104 * The interaction between the bridges and other frameworks involved in
105 * the probing of the upstream driver and the bridge driver can be
106 * challenging. Indeed, there's multiple cases that needs to be
107 * considered:
108 *
109 * - The upstream driver doesn't use the component framework and isn't a
110 * MIPI-DSI host. In this case, the bridge driver will probe at some
111 * point and the upstream driver should try to probe again by returning
112 * EPROBE_DEFER as long as the bridge driver hasn't probed.
113 *
114 * - The upstream driver doesn't use the component framework, but is a
115 * MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
116 * controlled. In this case, the bridge device is a child of the
117 * display device and when it will probe it's assured that the display
118 * device (and MIPI-DSI host) is present. The upstream driver will be
119 * assured that the bridge driver is connected between the
120 * &mipi_dsi_host_ops.attach and &mipi_dsi_host_ops.detach operations.
121 * Therefore, it must run mipi_dsi_host_register() in its probe
122 * function, and then run drm_bridge_attach() in its
123 * &mipi_dsi_host_ops.attach hook.
124 *
125 * - The upstream driver uses the component framework and is a MIPI-DSI
126 * host. The bridge device uses the MIPI-DCS commands to be
127 * controlled. This is the same situation than above, and can run
128 * mipi_dsi_host_register() in either its probe or bind hooks.
129 *
130 * - The upstream driver uses the component framework and is a MIPI-DSI
131 * host. The bridge device uses a separate bus (such as I2C) to be
132 * controlled. In this case, there's no correlation between the probe
133 * of the bridge and upstream drivers, so care must be taken to avoid
134 * an endless EPROBE_DEFER loop, with each driver waiting for the
135 * other to probe.
136 *
137 * The ideal pattern to cover the last item (and all the others in the
138 * MIPI-DSI host driver case) is to split the operations like this:
139 *
140 * - The MIPI-DSI host driver must run mipi_dsi_host_register() in its
141 * probe hook. It will make sure that the MIPI-DSI host sticks around,
142 * and that the driver's bind can be called.
143 *
144 * - In its probe hook, the bridge driver must try to find its MIPI-DSI
145 * host, register as a MIPI-DSI device and attach the MIPI-DSI device
146 * to its host. The bridge driver is now functional.
147 *
148 * - In its &struct mipi_dsi_host_ops.attach hook, the MIPI-DSI host can
149 * now add its component. Its bind hook will now be called and since
150 * the bridge driver is attached and registered, we can now look for
151 * and attach it.
152 *
153 * At this point, we're now certain that both the upstream driver and
154 * the bridge driver are functional and we can't have a deadlock-like
155 * situation when probing.
156 */
157
158/**
159 * DOC: dsi bridge operations
160 *
161 * DSI host interfaces are expected to be implemented as bridges rather than
162 * encoders, however there are a few aspects of their operation that need to
163 * be defined in order to provide a consistent interface.
164 *
165 * A DSI host should keep the PHY powered down until the pre_enable operation is
166 * called. All lanes are in an undefined idle state up to this point, and it
167 * must not be assumed that it is LP-11.
168 * pre_enable should initialise the PHY, set the data lanes to LP-11, and the
169 * clock lane to either LP-11 or HS depending on the mode_flag
170 * %MIPI_DSI_CLOCK_NON_CONTINUOUS.
171 *
172 * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
173 * called before the DSI host. If the DSI peripheral requires LP-11 and/or
174 * the clock lane to be in HS mode prior to pre_enable, then it can set the
175 * &pre_enable_prev_first flag to request the pre_enable (and
176 * post_disable) order to be altered to enable the DSI host first.
177 *
178 * Either the CRTC being enabled, or the DSI host enable operation should switch
179 * the host to actively transmitting video on the data lanes.
180 *
181 * The reverse also applies. The DSI host disable operation or stopping the CRTC
182 * should stop transmitting video, and the data lanes should return to the LP-11
183 * state. The DSI host &post_disable operation should disable the PHY.
184 * If the &pre_enable_prev_first flag is set, then the DSI peripheral's
185 * bridge &post_disable will be called before the DSI host's post_disable.
186 *
187 * Whilst it is valid to call &host_transfer prior to pre_enable or after
188 * post_disable, the exact state of the lanes is undefined at this point. The
189 * DSI host should initialise the interface, transmit the data, and then disable
190 * the interface again.
191 *
192 * Ultra Low Power State (ULPS) is not explicitly supported by DRM. If
193 * implemented, it therefore needs to be handled entirely within the DSI Host
194 * driver.
195 */
196
197static DEFINE_MUTEX(bridge_lock);
198static LIST_HEAD(bridge_list);
199
200/**
201 * drm_bridge_add - add the given bridge to the global bridge list
202 *
203 * @bridge: bridge control structure
204 */
205void drm_bridge_add(struct drm_bridge *bridge)
206{
207 mutex_init(&bridge->hpd_mutex);
208
209 mutex_lock(&bridge_lock);
210 list_add_tail(&bridge->list, &bridge_list);
211 mutex_unlock(&bridge_lock);
212}
213EXPORT_SYMBOL(drm_bridge_add);
214
215static void drm_bridge_remove_void(void *bridge)
216{
217 drm_bridge_remove(bridge);
218}
219
220/**
221 * devm_drm_bridge_add - devm managed version of drm_bridge_add()
222 *
223 * @dev: device to tie the bridge lifetime to
224 * @bridge: bridge control structure
225 *
226 * This is the managed version of drm_bridge_add() which automatically
227 * calls drm_bridge_remove() when @dev is unbound.
228 *
229 * Return: 0 if no error or negative error code.
230 */
231int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
232{
233 drm_bridge_add(bridge);
234 return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
235}
236EXPORT_SYMBOL(devm_drm_bridge_add);
237
238/**
239 * drm_bridge_remove - remove the given bridge from the global bridge list
240 *
241 * @bridge: bridge control structure
242 */
243void drm_bridge_remove(struct drm_bridge *bridge)
244{
245 mutex_lock(&bridge_lock);
246 list_del_init(&bridge->list);
247 mutex_unlock(&bridge_lock);
248
249 mutex_destroy(&bridge->hpd_mutex);
250}
251EXPORT_SYMBOL(drm_bridge_remove);
252
253static struct drm_private_state *
254drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
255{
256 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
257 struct drm_bridge_state *state;
258
259 state = bridge->funcs->atomic_duplicate_state(bridge);
260 return state ? &state->base : NULL;
261}
262
263static void
264drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
265 struct drm_private_state *s)
266{
267 struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
268 struct drm_bridge *bridge = drm_priv_to_bridge(obj);
269
270 bridge->funcs->atomic_destroy_state(bridge, state);
271}
272
273static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
274 .atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
275 .atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
276};
277
278/**
279 * drm_bridge_attach - attach the bridge to an encoder's chain
280 *
281 * @encoder: DRM encoder
282 * @bridge: bridge to attach
283 * @previous: previous bridge in the chain (optional)
284 * @flags: DRM_BRIDGE_ATTACH_* flags
285 *
286 * Called by a kms driver to link the bridge to an encoder's chain. The previous
287 * argument specifies the previous bridge in the chain. If NULL, the bridge is
288 * linked directly at the encoder's output. Otherwise it is linked at the
289 * previous bridge's output.
290 *
291 * If non-NULL the previous bridge must be already attached by a call to this
292 * function.
293 *
294 * Note that bridges attached to encoders are auto-detached during encoder
295 * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
296 * *not* be balanced with a drm_bridge_detach() in driver code.
297 *
298 * RETURNS:
299 * Zero on success, error code on failure
300 */
301int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
302 struct drm_bridge *previous,
303 enum drm_bridge_attach_flags flags)
304{
305 int ret;
306
307 if (!encoder || !bridge)
308 return -EINVAL;
309
310 if (previous && (!previous->dev || previous->encoder != encoder))
311 return -EINVAL;
312
313 if (bridge->dev)
314 return -EBUSY;
315
316 bridge->dev = encoder->dev;
317 bridge->encoder = encoder;
318
319 if (previous)
320 list_add(&bridge->chain_node, &previous->chain_node);
321 else
322 list_add(&bridge->chain_node, &encoder->bridge_chain);
323
324 if (bridge->funcs->attach) {
325 ret = bridge->funcs->attach(bridge, flags);
326 if (ret < 0)
327 goto err_reset_bridge;
328 }
329
330 if (bridge->funcs->atomic_reset) {
331 struct drm_bridge_state *state;
332
333 state = bridge->funcs->atomic_reset(bridge);
334 if (IS_ERR(state)) {
335 ret = PTR_ERR(state);
336 goto err_detach_bridge;
337 }
338
339 drm_atomic_private_obj_init(bridge->dev, &bridge->base,
340 &state->base,
341 &drm_bridge_priv_state_funcs);
342 }
343
344 return 0;
345
346err_detach_bridge:
347 if (bridge->funcs->detach)
348 bridge->funcs->detach(bridge);
349
350err_reset_bridge:
351 bridge->dev = NULL;
352 bridge->encoder = NULL;
353 list_del(&bridge->chain_node);
354
355#ifdef CONFIG_OF
356 DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
357 bridge->of_node, encoder->name, ret);
358#else
359 DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
360 encoder->name, ret);
361#endif
362
363 return ret;
364}
365EXPORT_SYMBOL(drm_bridge_attach);
366
367void drm_bridge_detach(struct drm_bridge *bridge)
368{
369 if (WARN_ON(!bridge))
370 return;
371
372 if (WARN_ON(!bridge->dev))
373 return;
374
375 if (bridge->funcs->atomic_reset)
376 drm_atomic_private_obj_fini(&bridge->base);
377
378 if (bridge->funcs->detach)
379 bridge->funcs->detach(bridge);
380
381 list_del(&bridge->chain_node);
382 bridge->dev = NULL;
383}
384
385/**
386 * DOC: bridge operations
387 *
388 * Bridge drivers expose operations through the &drm_bridge_funcs structure.
389 * The DRM internals (atomic and CRTC helpers) use the helpers defined in
390 * drm_bridge.c to call bridge operations. Those operations are divided in
391 * three big categories to support different parts of the bridge usage.
392 *
393 * - The encoder-related operations support control of the bridges in the
394 * chain, and are roughly counterparts to the &drm_encoder_helper_funcs
395 * operations. They are used by the legacy CRTC and the atomic modeset
396 * helpers to perform mode validation, fixup and setting, and enable and
397 * disable the bridge automatically.
398 *
399 * The enable and disable operations are split in
400 * &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
401 * &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
402 * finer-grained control.
403 *
404 * Bridge drivers may implement the legacy version of those operations, or
405 * the atomic version (prefixed with atomic\_), in which case they shall also
406 * implement the atomic state bookkeeping operations
407 * (&drm_bridge_funcs.atomic_duplicate_state,
408 * &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
409 * Mixing atomic and non-atomic versions of the operations is not supported.
410 *
411 * - The bus format negotiation operations
412 * &drm_bridge_funcs.atomic_get_output_bus_fmts and
413 * &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
414 * negotiate the formats transmitted between bridges in the chain when
415 * multiple formats are supported. Negotiation for formats is performed
416 * transparently for display drivers by the atomic modeset helpers. Only
417 * atomic versions of those operations exist, bridge drivers that need to
418 * implement them shall thus also implement the atomic version of the
419 * encoder-related operations. This feature is not supported by the legacy
420 * CRTC helpers.
421 *
422 * - The connector-related operations support implementing a &drm_connector
423 * based on a chain of bridges. DRM bridges traditionally create a
424 * &drm_connector for bridges meant to be used at the end of the chain. This
425 * puts additional burden on bridge drivers, especially for bridges that may
426 * be used in the middle of a chain or at the end of it. Furthermore, it
427 * requires all operations of the &drm_connector to be handled by a single
428 * bridge, which doesn't always match the hardware architecture.
429 *
430 * To simplify bridge drivers and make the connector implementation more
431 * flexible, a new model allows bridges to unconditionally skip creation of
432 * &drm_connector and instead expose &drm_bridge_funcs operations to support
433 * an externally-implemented &drm_connector. Those operations are
434 * &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
435 * &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
436 * &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
437 * implemented, display drivers shall create a &drm_connector instance for
438 * each chain of bridges, and implement those connector instances based on
439 * the bridge connector operations.
440 *
441 * Bridge drivers shall implement the connector-related operations for all
442 * the features that the bridge hardware support. For instance, if a bridge
443 * supports reading EDID, the &drm_bridge_funcs.get_edid shall be
444 * implemented. This however doesn't mean that the DDC lines are wired to the
445 * bridge on a particular platform, as they could also be connected to an I2C
446 * controller of the SoC. Support for the connector-related operations on the
447 * running platform is reported through the &drm_bridge.ops flags. Bridge
448 * drivers shall detect which operations they can support on the platform
449 * (usually this information is provided by ACPI or DT), and set the
450 * &drm_bridge.ops flags for all supported operations. A flag shall only be
451 * set if the corresponding &drm_bridge_funcs operation is implemented, but
452 * an implemented operation doesn't necessarily imply that the corresponding
453 * flag will be set. Display drivers shall use the &drm_bridge.ops flags to
454 * decide which bridge to delegate a connector operation to. This mechanism
455 * allows providing a single static const &drm_bridge_funcs instance in
456 * bridge drivers, improving security by storing function pointers in
457 * read-only memory.
458 *
459 * In order to ease transition, bridge drivers may support both the old and
460 * new models by making connector creation optional and implementing the
461 * connected-related bridge operations. Connector creation is then controlled
462 * by the flags argument to the drm_bridge_attach() function. Display drivers
463 * that support the new model and create connectors themselves shall set the
464 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
465 * connector creation. For intermediate bridges in the chain, the flag shall
466 * be passed to the drm_bridge_attach() call for the downstream bridge.
467 * Bridge drivers that implement the new model only shall return an error
468 * from their &drm_bridge_funcs.attach handler when the
469 * %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
470 * should use the new model, and convert the bridge drivers they use if
471 * needed, in order to gradually transition to the new model.
472 */
473
474/**
475 * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
476 * encoder chain
477 * @bridge: bridge control structure
478 * @mode: desired mode to be set for the bridge
479 * @adjusted_mode: updated mode that works for this bridge
480 *
481 * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
482 * encoder chain, starting from the first bridge to the last.
483 *
484 * Note: the bridge passed should be the one closest to the encoder
485 *
486 * RETURNS:
487 * true on success, false on failure
488 */
489bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
490 const struct drm_display_mode *mode,
491 struct drm_display_mode *adjusted_mode)
492{
493 struct drm_encoder *encoder;
494
495 if (!bridge)
496 return true;
497
498 encoder = bridge->encoder;
499 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
500 if (!bridge->funcs->mode_fixup)
501 continue;
502
503 if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
504 return false;
505 }
506
507 return true;
508}
509EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
510
511/**
512 * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
513 * encoder chain.
514 * @bridge: bridge control structure
515 * @info: display info against which the mode shall be validated
516 * @mode: desired mode to be validated
517 *
518 * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
519 * chain, starting from the first bridge to the last. If at least one bridge
520 * does not accept the mode the function returns the error code.
521 *
522 * Note: the bridge passed should be the one closest to the encoder.
523 *
524 * RETURNS:
525 * MODE_OK on success, drm_mode_status Enum error code on failure
526 */
527enum drm_mode_status
528drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
529 const struct drm_display_info *info,
530 const struct drm_display_mode *mode)
531{
532 struct drm_encoder *encoder;
533
534 if (!bridge)
535 return MODE_OK;
536
537 encoder = bridge->encoder;
538 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
539 enum drm_mode_status ret;
540
541 if (!bridge->funcs->mode_valid)
542 continue;
543
544 ret = bridge->funcs->mode_valid(bridge, info, mode);
545 if (ret != MODE_OK)
546 return ret;
547 }
548
549 return MODE_OK;
550}
551EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
552
553/**
554 * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
555 * encoder chain
556 * @bridge: bridge control structure
557 * @mode: desired mode to be set for the encoder chain
558 * @adjusted_mode: updated mode that works for this encoder chain
559 *
560 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
561 * encoder chain, starting from the first bridge to the last.
562 *
563 * Note: the bridge passed should be the one closest to the encoder
564 */
565void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
566 const struct drm_display_mode *mode,
567 const struct drm_display_mode *adjusted_mode)
568{
569 struct drm_encoder *encoder;
570
571 if (!bridge)
572 return;
573
574 encoder = bridge->encoder;
575 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
576 if (bridge->funcs->mode_set)
577 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
578 }
579}
580EXPORT_SYMBOL(drm_bridge_chain_mode_set);
581
582/**
583 * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
584 * @bridge: bridge control structure
585 * @old_state: old atomic state
586 *
587 * Calls &drm_bridge_funcs.atomic_disable (falls back on
588 * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
589 * starting from the last bridge to the first. These are called before calling
590 * &drm_encoder_helper_funcs.atomic_disable
591 *
592 * Note: the bridge passed should be the one closest to the encoder
593 */
594void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
595 struct drm_atomic_state *old_state)
596{
597 struct drm_encoder *encoder;
598 struct drm_bridge *iter;
599
600 if (!bridge)
601 return;
602
603 encoder = bridge->encoder;
604 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
605 if (iter->funcs->atomic_disable) {
606 struct drm_bridge_state *old_bridge_state;
607
608 old_bridge_state =
609 drm_atomic_get_old_bridge_state(old_state,
610 iter);
611 if (WARN_ON(!old_bridge_state))
612 return;
613
614 iter->funcs->atomic_disable(iter, old_bridge_state);
615 } else if (iter->funcs->disable) {
616 iter->funcs->disable(iter);
617 }
618
619 if (iter == bridge)
620 break;
621 }
622}
623EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
624
625static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
626 struct drm_atomic_state *old_state)
627{
628 if (old_state && bridge->funcs->atomic_post_disable) {
629 struct drm_bridge_state *old_bridge_state;
630
631 old_bridge_state =
632 drm_atomic_get_old_bridge_state(old_state,
633 bridge);
634 if (WARN_ON(!old_bridge_state))
635 return;
636
637 bridge->funcs->atomic_post_disable(bridge,
638 old_bridge_state);
639 } else if (bridge->funcs->post_disable) {
640 bridge->funcs->post_disable(bridge);
641 }
642}
643
644/**
645 * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
646 * in the encoder chain
647 * @bridge: bridge control structure
648 * @old_state: old atomic state
649 *
650 * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
651 * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
652 * starting from the first bridge to the last. These are called after completing
653 * &drm_encoder_helper_funcs.atomic_disable
654 *
655 * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
656 * bridge will be called before the previous one to reverse the @pre_enable
657 * calling direction.
658 *
659 * Note: the bridge passed should be the one closest to the encoder
660 */
661void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
662 struct drm_atomic_state *old_state)
663{
664 struct drm_encoder *encoder;
665 struct drm_bridge *next, *limit;
666
667 if (!bridge)
668 return;
669
670 encoder = bridge->encoder;
671
672 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
673 limit = NULL;
674
675 if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
676 next = list_next_entry(bridge, chain_node);
677
678 if (next->pre_enable_prev_first) {
679 /* next bridge had requested that prev
680 * was enabled first, so disabled last
681 */
682 limit = next;
683
684 /* Find the next bridge that has NOT requested
685 * prev to be enabled first / disabled last
686 */
687 list_for_each_entry_from(next, &encoder->bridge_chain,
688 chain_node) {
689 if (next->pre_enable_prev_first) {
690 next = list_prev_entry(next, chain_node);
691 limit = next;
692 break;
693 }
694 }
695
696 /* Call these bridges in reverse order */
697 list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
698 chain_node) {
699 if (next == bridge)
700 break;
701
702 drm_atomic_bridge_call_post_disable(next,
703 old_state);
704 }
705 }
706 }
707
708 drm_atomic_bridge_call_post_disable(bridge, old_state);
709
710 if (limit)
711 /* Jump all bridges that we have already post_disabled */
712 bridge = limit;
713 }
714}
715EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
716
717static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
718 struct drm_atomic_state *old_state)
719{
720 if (old_state && bridge->funcs->atomic_pre_enable) {
721 struct drm_bridge_state *old_bridge_state;
722
723 old_bridge_state =
724 drm_atomic_get_old_bridge_state(old_state,
725 bridge);
726 if (WARN_ON(!old_bridge_state))
727 return;
728
729 bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
730 } else if (bridge->funcs->pre_enable) {
731 bridge->funcs->pre_enable(bridge);
732 }
733}
734
735/**
736 * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
737 * the encoder chain
738 * @bridge: bridge control structure
739 * @old_state: old atomic state
740 *
741 * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
742 * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
743 * starting from the last bridge to the first. These are called before calling
744 * &drm_encoder_helper_funcs.atomic_enable
745 *
746 * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
747 * prev bridge will be called before pre_enable of this bridge.
748 *
749 * Note: the bridge passed should be the one closest to the encoder
750 */
751void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
752 struct drm_atomic_state *old_state)
753{
754 struct drm_encoder *encoder;
755 struct drm_bridge *iter, *next, *limit;
756
757 if (!bridge)
758 return;
759
760 encoder = bridge->encoder;
761
762 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
763 if (iter->pre_enable_prev_first) {
764 next = iter;
765 limit = bridge;
766 list_for_each_entry_from_reverse(next,
767 &encoder->bridge_chain,
768 chain_node) {
769 if (next == bridge)
770 break;
771
772 if (!next->pre_enable_prev_first) {
773 /* Found first bridge that does NOT
774 * request prev to be enabled first
775 */
776 limit = list_prev_entry(next, chain_node);
777 break;
778 }
779 }
780
781 list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
782 /* Call requested prev bridge pre_enable
783 * in order.
784 */
785 if (next == iter)
786 /* At the first bridge to request prev
787 * bridges called first.
788 */
789 break;
790
791 drm_atomic_bridge_call_pre_enable(next, old_state);
792 }
793 }
794
795 drm_atomic_bridge_call_pre_enable(iter, old_state);
796
797 if (iter->pre_enable_prev_first)
798 /* Jump all bridges that we have already pre_enabled */
799 iter = limit;
800
801 if (iter == bridge)
802 break;
803 }
804}
805EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
806
807/**
808 * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
809 * @bridge: bridge control structure
810 * @old_state: old atomic state
811 *
812 * Calls &drm_bridge_funcs.atomic_enable (falls back on
813 * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
814 * starting from the first bridge to the last. These are called after completing
815 * &drm_encoder_helper_funcs.atomic_enable
816 *
817 * Note: the bridge passed should be the one closest to the encoder
818 */
819void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
820 struct drm_atomic_state *old_state)
821{
822 struct drm_encoder *encoder;
823
824 if (!bridge)
825 return;
826
827 encoder = bridge->encoder;
828 list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
829 if (bridge->funcs->atomic_enable) {
830 struct drm_bridge_state *old_bridge_state;
831
832 old_bridge_state =
833 drm_atomic_get_old_bridge_state(old_state,
834 bridge);
835 if (WARN_ON(!old_bridge_state))
836 return;
837
838 bridge->funcs->atomic_enable(bridge, old_bridge_state);
839 } else if (bridge->funcs->enable) {
840 bridge->funcs->enable(bridge);
841 }
842 }
843}
844EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
845
846static int drm_atomic_bridge_check(struct drm_bridge *bridge,
847 struct drm_crtc_state *crtc_state,
848 struct drm_connector_state *conn_state)
849{
850 if (bridge->funcs->atomic_check) {
851 struct drm_bridge_state *bridge_state;
852 int ret;
853
854 bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
855 bridge);
856 if (WARN_ON(!bridge_state))
857 return -EINVAL;
858
859 ret = bridge->funcs->atomic_check(bridge, bridge_state,
860 crtc_state, conn_state);
861 if (ret)
862 return ret;
863 } else if (bridge->funcs->mode_fixup) {
864 if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
865 &crtc_state->adjusted_mode))
866 return -EINVAL;
867 }
868
869 return 0;
870}
871
872static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
873 struct drm_bridge *cur_bridge,
874 struct drm_crtc_state *crtc_state,
875 struct drm_connector_state *conn_state,
876 u32 out_bus_fmt)
877{
878 unsigned int i, num_in_bus_fmts = 0;
879 struct drm_bridge_state *cur_state;
880 struct drm_bridge *prev_bridge;
881 u32 *in_bus_fmts;
882 int ret;
883
884 prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
885 cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
886 cur_bridge);
887
888 /*
889 * If bus format negotiation is not supported by this bridge, let's
890 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
891 * hope that it can handle this situation gracefully (by providing
892 * appropriate default values).
893 */
894 if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
895 if (cur_bridge != first_bridge) {
896 ret = select_bus_fmt_recursive(first_bridge,
897 prev_bridge, crtc_state,
898 conn_state,
899 MEDIA_BUS_FMT_FIXED);
900 if (ret)
901 return ret;
902 }
903
904 /*
905 * Driver does not implement the atomic state hooks, but that's
906 * fine, as long as it does not access the bridge state.
907 */
908 if (cur_state) {
909 cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
910 cur_state->output_bus_cfg.format = out_bus_fmt;
911 }
912
913 return 0;
914 }
915
916 /*
917 * If the driver implements ->atomic_get_input_bus_fmts() it
918 * should also implement the atomic state hooks.
919 */
920 if (WARN_ON(!cur_state))
921 return -EINVAL;
922
923 in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
924 cur_state,
925 crtc_state,
926 conn_state,
927 out_bus_fmt,
928 &num_in_bus_fmts);
929 if (!num_in_bus_fmts)
930 return -ENOTSUPP;
931 else if (!in_bus_fmts)
932 return -ENOMEM;
933
934 if (first_bridge == cur_bridge) {
935 cur_state->input_bus_cfg.format = in_bus_fmts[0];
936 cur_state->output_bus_cfg.format = out_bus_fmt;
937 kfree(in_bus_fmts);
938 return 0;
939 }
940
941 for (i = 0; i < num_in_bus_fmts; i++) {
942 ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
943 crtc_state, conn_state,
944 in_bus_fmts[i]);
945 if (ret != -ENOTSUPP)
946 break;
947 }
948
949 if (!ret) {
950 cur_state->input_bus_cfg.format = in_bus_fmts[i];
951 cur_state->output_bus_cfg.format = out_bus_fmt;
952 }
953
954 kfree(in_bus_fmts);
955 return ret;
956}
957
958/*
959 * This function is called by &drm_atomic_bridge_chain_check() just before
960 * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
961 * It performs bus format negotiation between bridge elements. The negotiation
962 * happens in reverse order, starting from the last element in the chain up to
963 * @bridge.
964 *
965 * Negotiation starts by retrieving supported output bus formats on the last
966 * bridge element and testing them one by one. The test is recursive, meaning
967 * that for each tested output format, the whole chain will be walked backward,
968 * and each element will have to choose an input bus format that can be
969 * transcoded to the requested output format. When a bridge element does not
970 * support transcoding into a specific output format -ENOTSUPP is returned and
971 * the next bridge element will have to try a different format. If none of the
972 * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
973 *
974 * This implementation is relying on
975 * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
976 * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
977 * input/output formats.
978 *
979 * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
980 * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
981 * tries a single format: &drm_connector.display_info.bus_formats[0] if
982 * available, MEDIA_BUS_FMT_FIXED otherwise.
983 *
984 * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
985 * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
986 * bridge element that lacks this hook and asks the previous element in the
987 * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
988 * to do in that case (fail if they want to enforce bus format negotiation, or
989 * provide a reasonable default if they need to support pipelines where not
990 * all elements support bus format negotiation).
991 */
992static int
993drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
994 struct drm_crtc_state *crtc_state,
995 struct drm_connector_state *conn_state)
996{
997 struct drm_connector *conn = conn_state->connector;
998 struct drm_encoder *encoder = bridge->encoder;
999 struct drm_bridge_state *last_bridge_state;
1000 unsigned int i, num_out_bus_fmts = 0;
1001 struct drm_bridge *last_bridge;
1002 u32 *out_bus_fmts;
1003 int ret = 0;
1004
1005 last_bridge = list_last_entry(&encoder->bridge_chain,
1006 struct drm_bridge, chain_node);
1007 last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
1008 last_bridge);
1009
1010 if (last_bridge->funcs->atomic_get_output_bus_fmts) {
1011 const struct drm_bridge_funcs *funcs = last_bridge->funcs;
1012
1013 /*
1014 * If the driver implements ->atomic_get_output_bus_fmts() it
1015 * should also implement the atomic state hooks.
1016 */
1017 if (WARN_ON(!last_bridge_state))
1018 return -EINVAL;
1019
1020 out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
1021 last_bridge_state,
1022 crtc_state,
1023 conn_state,
1024 &num_out_bus_fmts);
1025 if (!num_out_bus_fmts)
1026 return -ENOTSUPP;
1027 else if (!out_bus_fmts)
1028 return -ENOMEM;
1029 } else {
1030 num_out_bus_fmts = 1;
1031 out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
1032 if (!out_bus_fmts)
1033 return -ENOMEM;
1034
1035 if (conn->display_info.num_bus_formats &&
1036 conn->display_info.bus_formats)
1037 out_bus_fmts[0] = conn->display_info.bus_formats[0];
1038 else
1039 out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
1040 }
1041
1042 for (i = 0; i < num_out_bus_fmts; i++) {
1043 ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
1044 conn_state, out_bus_fmts[i]);
1045 if (ret != -ENOTSUPP)
1046 break;
1047 }
1048
1049 kfree(out_bus_fmts);
1050
1051 return ret;
1052}
1053
1054static void
1055drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
1056 struct drm_connector *conn,
1057 struct drm_atomic_state *state)
1058{
1059 struct drm_bridge_state *bridge_state, *next_bridge_state;
1060 struct drm_bridge *next_bridge;
1061 u32 output_flags = 0;
1062
1063 bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
1064
1065 /* No bridge state attached to this bridge => nothing to propagate. */
1066 if (!bridge_state)
1067 return;
1068
1069 next_bridge = drm_bridge_get_next_bridge(bridge);
1070
1071 /*
1072 * Let's try to apply the most common case here, that is, propagate
1073 * display_info flags for the last bridge, and propagate the input
1074 * flags of the next bridge element to the output end of the current
1075 * bridge when the bridge is not the last one.
1076 * There are exceptions to this rule, like when signal inversion is
1077 * happening at the board level, but that's something drivers can deal
1078 * with from their &drm_bridge_funcs.atomic_check() implementation by
1079 * simply overriding the flags value we've set here.
1080 */
1081 if (!next_bridge) {
1082 output_flags = conn->display_info.bus_flags;
1083 } else {
1084 next_bridge_state = drm_atomic_get_new_bridge_state(state,
1085 next_bridge);
1086 /*
1087 * No bridge state attached to the next bridge, just leave the
1088 * flags to 0.
1089 */
1090 if (next_bridge_state)
1091 output_flags = next_bridge_state->input_bus_cfg.flags;
1092 }
1093
1094 bridge_state->output_bus_cfg.flags = output_flags;
1095
1096 /*
1097 * Propagate the output flags to the input end of the bridge. Again, it's
1098 * not necessarily what all bridges want, but that's what most of them
1099 * do, and by doing that by default we avoid forcing drivers to
1100 * duplicate the "dummy propagation" logic.
1101 */
1102 bridge_state->input_bus_cfg.flags = output_flags;
1103}
1104
1105/**
1106 * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1107 * @bridge: bridge control structure
1108 * @crtc_state: new CRTC state
1109 * @conn_state: new connector state
1110 *
1111 * First trigger a bus format negotiation before calling
1112 * &drm_bridge_funcs.atomic_check() (falls back on
1113 * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1114 * starting from the last bridge to the first. These are called before calling
1115 * &drm_encoder_helper_funcs.atomic_check()
1116 *
1117 * RETURNS:
1118 * 0 on success, a negative error code on failure
1119 */
1120int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1121 struct drm_crtc_state *crtc_state,
1122 struct drm_connector_state *conn_state)
1123{
1124 struct drm_connector *conn = conn_state->connector;
1125 struct drm_encoder *encoder;
1126 struct drm_bridge *iter;
1127 int ret;
1128
1129 if (!bridge)
1130 return 0;
1131
1132 ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1133 conn_state);
1134 if (ret)
1135 return ret;
1136
1137 encoder = bridge->encoder;
1138 list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1139 int ret;
1140
1141 /*
1142 * Bus flags are propagated by default. If a bridge needs to
1143 * tweak the input bus flags for any reason, it should happen
1144 * in its &drm_bridge_funcs.atomic_check() implementation such
1145 * that preceding bridges in the chain can propagate the new
1146 * bus flags.
1147 */
1148 drm_atomic_bridge_propagate_bus_flags(iter, conn,
1149 crtc_state->state);
1150
1151 ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1152 if (ret)
1153 return ret;
1154
1155 if (iter == bridge)
1156 break;
1157 }
1158
1159 return 0;
1160}
1161EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1162
1163/**
1164 * drm_bridge_detect - check if anything is attached to the bridge output
1165 * @bridge: bridge control structure
1166 *
1167 * If the bridge supports output detection, as reported by the
1168 * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1169 * bridge and return the connection status. Otherwise return
1170 * connector_status_unknown.
1171 *
1172 * RETURNS:
1173 * The detection status on success, or connector_status_unknown if the bridge
1174 * doesn't support output detection.
1175 */
1176enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1177{
1178 if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1179 return connector_status_unknown;
1180
1181 return bridge->funcs->detect(bridge);
1182}
1183EXPORT_SYMBOL_GPL(drm_bridge_detect);
1184
1185/**
1186 * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1187 * @connector
1188 * @bridge: bridge control structure
1189 * @connector: the connector to fill with modes
1190 *
1191 * If the bridge supports output modes retrieval, as reported by the
1192 * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1193 * fill the connector with all valid modes and return the number of modes
1194 * added. Otherwise return 0.
1195 *
1196 * RETURNS:
1197 * The number of modes added to the connector.
1198 */
1199int drm_bridge_get_modes(struct drm_bridge *bridge,
1200 struct drm_connector *connector)
1201{
1202 if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1203 return 0;
1204
1205 return bridge->funcs->get_modes(bridge, connector);
1206}
1207EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1208
1209/**
1210 * drm_bridge_get_edid - get the EDID data of the connected display
1211 * @bridge: bridge control structure
1212 * @connector: the connector to read EDID for
1213 *
1214 * If the bridge supports output EDID retrieval, as reported by the
1215 * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1216 * get the EDID and return it. Otherwise return NULL.
1217 *
1218 * RETURNS:
1219 * The retrieved EDID on success, or NULL otherwise.
1220 */
1221struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1222 struct drm_connector *connector)
1223{
1224 if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1225 return NULL;
1226
1227 return bridge->funcs->get_edid(bridge, connector);
1228}
1229EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1230
1231/**
1232 * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1233 * @bridge: bridge control structure
1234 * @cb: hot-plug detection callback
1235 * @data: data to be passed to the hot-plug detection callback
1236 *
1237 * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1238 * and @data as hot plug notification callback. From now on the @cb will be
1239 * called with @data when an output status change is detected by the bridge,
1240 * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1241 *
1242 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1243 * bridge->ops. This function shall not be called when the flag is not set.
1244 *
1245 * Only one hot plug detection callback can be registered at a time, it is an
1246 * error to call this function when hot plug detection is already enabled for
1247 * the bridge.
1248 */
1249void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1250 void (*cb)(void *data,
1251 enum drm_connector_status status),
1252 void *data)
1253{
1254 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1255 return;
1256
1257 mutex_lock(&bridge->hpd_mutex);
1258
1259 if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1260 goto unlock;
1261
1262 bridge->hpd_cb = cb;
1263 bridge->hpd_data = data;
1264
1265 if (bridge->funcs->hpd_enable)
1266 bridge->funcs->hpd_enable(bridge);
1267
1268unlock:
1269 mutex_unlock(&bridge->hpd_mutex);
1270}
1271EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1272
1273/**
1274 * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1275 * @bridge: bridge control structure
1276 *
1277 * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1278 * plug detection callback previously registered with drm_bridge_hpd_enable().
1279 * Once this function returns the callback will not be called by the bridge
1280 * when an output status change occurs.
1281 *
1282 * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1283 * bridge->ops. This function shall not be called when the flag is not set.
1284 */
1285void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1286{
1287 if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1288 return;
1289
1290 mutex_lock(&bridge->hpd_mutex);
1291 if (bridge->funcs->hpd_disable)
1292 bridge->funcs->hpd_disable(bridge);
1293
1294 bridge->hpd_cb = NULL;
1295 bridge->hpd_data = NULL;
1296 mutex_unlock(&bridge->hpd_mutex);
1297}
1298EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1299
1300/**
1301 * drm_bridge_hpd_notify - notify hot plug detection events
1302 * @bridge: bridge control structure
1303 * @status: output connection status
1304 *
1305 * Bridge drivers shall call this function to report hot plug events when they
1306 * detect a change in the output status, when hot plug detection has been
1307 * enabled by drm_bridge_hpd_enable().
1308 *
1309 * This function shall be called in a context that can sleep.
1310 */
1311void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1312 enum drm_connector_status status)
1313{
1314 mutex_lock(&bridge->hpd_mutex);
1315 if (bridge->hpd_cb)
1316 bridge->hpd_cb(bridge->hpd_data, status);
1317 mutex_unlock(&bridge->hpd_mutex);
1318}
1319EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1320
1321#ifdef CONFIG_OF
1322/**
1323 * of_drm_find_bridge - find the bridge corresponding to the device node in
1324 * the global bridge list
1325 *
1326 * @np: device node
1327 *
1328 * RETURNS:
1329 * drm_bridge control struct on success, NULL on failure
1330 */
1331struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1332{
1333 struct drm_bridge *bridge;
1334
1335 mutex_lock(&bridge_lock);
1336
1337 list_for_each_entry(bridge, &bridge_list, list) {
1338 if (bridge->of_node == np) {
1339 mutex_unlock(&bridge_lock);
1340 return bridge;
1341 }
1342 }
1343
1344 mutex_unlock(&bridge_lock);
1345 return NULL;
1346}
1347EXPORT_SYMBOL(of_drm_find_bridge);
1348#endif
1349
1350MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1351MODULE_DESCRIPTION("DRM bridge infrastructure");
1352MODULE_LICENSE("GPL and additional rights");