drivers/gpu/drm/drm_bridge.c

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