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