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/media-bus-format.h>
  26 #include <linux/module.h>
  27 #include <linux/mutex.h>
  28
  29 #include <drm/drm_atomic_state_helper.h>
  30 #include <drm/drm_bridge.h>
  31 #include <drm/drm_encoder.h>
  32 #include <drm/drm_of.h>
  33 #include <drm/drm_print.h>
  34
  35 #include "drm_crtc_internal.h"
  36
  37 /**
  38  * DOC: overview
  39  *
  40  * &struct drm_bridge represents a device that hangs on to an encoder. These are
  41  * handy when a regular &drm_encoder entity isn't enough to represent the entire
  42  * encoder chain.
  43  *
  44  * A bridge is always attached to a single &drm_encoder at a time, but can be
  45  * either connected to it directly, or through a chain of bridges::
  46  *
  47  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
  48  *
  49  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
  50  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
  51  * Chaining multiple bridges to the output of a bridge, or the same bridge to
  52  * the output of different bridges, is not supported.
  53  *
  54  * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
  55  * CRTCs, encoders or connectors and hence are not visible to userspace. They
  56  * just provide additional hooks to get the desired output at the end of the
  57  * encoder chain.
  58  */
  59
  60 /**
  61  * DOC: display driver integration
  62  *
  63  * Display drivers are responsible for linking encoders with the first bridge
  64  * in the chains. This is done by acquiring the appropriate bridge with
  65  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
  66  * encoder with a call to drm_bridge_attach().
  67  *
  68  * Bridges are responsible for linking themselves with the next bridge in the
  69  * chain, if any. This is done the same way as for encoders, with the call to
  70  * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
  71  *
  72  * Once these links are created, the bridges can participate along with encoder
  73  * functions to perform mode validation and fixup (through
  74  * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
  75  * setting (through drm_bridge_chain_mode_set()), enable (through
  76  * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
  77  * and disable (through drm_atomic_bridge_chain_disable() and
  78  * drm_atomic_bridge_chain_post_disable()). Those functions call the
  79  * corresponding operations provided in &drm_bridge_funcs in sequence for all
  80  * bridges in the chain.
  81  *
  82  * For display drivers that use the atomic helpers
  83  * drm_atomic_helper_check_modeset(),
  84  * drm_atomic_helper_commit_modeset_enables() and
  85  * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
  86  * commit check and commit tail handlers, or through the higher-level
  87  * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
  88  * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
  89  * requires no intervention from the driver. For other drivers, the relevant
  90  * DRM bridge chain functions shall be called manually.
  91  *
  92  * Bridges also participate in implementing the &drm_connector at the end of
  93  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
  94  * helper to create the &drm_connector, or implement it manually on top of the
  95  * connector-related operations exposed by the bridge (see the overview
  96  * documentation of bridge operations for more details).
  97  */
  98
  99 /**
 100  * DOC: special care dsi
 101  *
 102  * The interaction between the bridges and other frameworks involved in
 103  * the probing of the upstream driver and the bridge driver can be
 104  * challenging. Indeed, there's multiple cases that needs to be
 105  * considered:
 106  *
 107  * - The upstream driver doesn't use the component framework and isn't a
 108  *   MIPI-DSI host. In this case, the bridge driver will probe at some
 109  *   point and the upstream driver should try to probe again by returning
 110  *   EPROBE_DEFER as long as the bridge driver hasn't probed.
 111  *
 112  * - The upstream driver doesn't use the component framework, but is a
 113  *   MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
 114  *   controlled. In this case, the bridge device is a child of the
 115  *   display device and when it will probe it's assured that the display
 116  *   device (and MIPI-DSI host) is present. The upstream driver will be
 117  *   assured that the bridge driver is connected between the
 118  *   &mipi_dsi_host_ops.attach and &mipi_dsi_host_ops.detach operations.
 119  *   Therefore, it must run mipi_dsi_host_register() in its probe
 120  *   function, and then run drm_bridge_attach() in its
 121  *   &mipi_dsi_host_ops.attach hook.
 122  *
 123  * - The upstream driver uses the component framework and is a MIPI-DSI
 124  *   host. The bridge device uses the MIPI-DCS commands to be
 125  *   controlled. This is the same situation than above, and can run
 126  *   mipi_dsi_host_register() in either its probe or bind hooks.
 127  *
 128  * - The upstream driver uses the component framework and is a MIPI-DSI
 129  *   host. The bridge device uses a separate bus (such as I2C) to be
 130  *   controlled. In this case, there's no correlation between the probe
 131  *   of the bridge and upstream drivers, so care must be taken to avoid
 132  *   an endless EPROBE_DEFER loop, with each driver waiting for the
 133  *   other to probe.
 134  *
 135  * The ideal pattern to cover the last item (and all the others in the
 136  * MIPI-DSI host driver case) is to split the operations like this:
 137  *
 138  * - The MIPI-DSI host driver must run mipi_dsi_host_register() in its
 139  *   probe hook. It will make sure that the MIPI-DSI host sticks around,
 140  *   and that the driver's bind can be called.
 141  *
 142  * - In its probe hook, the bridge driver must try to find its MIPI-DSI
 143  *   host, register as a MIPI-DSI device and attach the MIPI-DSI device
 144  *   to its host. The bridge driver is now functional.
 145  *
 146  * - In its &struct mipi_dsi_host_ops.attach hook, the MIPI-DSI host can
 147  *   now add its component. Its bind hook will now be called and since
 148  *   the bridge driver is attached and registered, we can now look for
 149  *   and attach it.
 150  *
 151  * At this point, we're now certain that both the upstream driver and
 152  * the bridge driver are functional and we can't have a deadlock-like
 153  * situation when probing.
 154  */
 155
 156 static DEFINE_MUTEX(bridge_lock);
 157 static LIST_HEAD(bridge_list);
 158
 159 /**
 160  * drm_bridge_add - add the given bridge to the global bridge list
 161  *
 162  * @bridge: bridge control structure
 163  */
 164 void drm_bridge_add(struct drm_bridge *bridge)
 165 {
 166         mutex_init(&bridge->hpd_mutex);
 167
 168         mutex_lock(&bridge_lock);
 169         list_add_tail(&bridge->list, &bridge_list);
 170         mutex_unlock(&bridge_lock);
 171 }
 172 EXPORT_SYMBOL(drm_bridge_add);
 173
 174 static void drm_bridge_remove_void(void *bridge)
 175 {
 176         drm_bridge_remove(bridge);
 177 }
 178
 179 /**
 180  * devm_drm_bridge_add - devm managed version of drm_bridge_add()
 181  *
 182  * @dev: device to tie the bridge lifetime to
 183  * @bridge: bridge control structure
 184  *
 185  * This is the managed version of drm_bridge_add() which automatically
 186  * calls drm_bridge_remove() when @dev is unbound.
 187  *
 188  * Return: 0 if no error or negative error code.
 189  */
 190 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
 191 {
 192         drm_bridge_add(bridge);
 193         return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
 194 }
 195 EXPORT_SYMBOL(devm_drm_bridge_add);
 196
 197 /**
 198  * drm_bridge_remove - remove the given bridge from the global bridge list
 199  *
 200  * @bridge: bridge control structure
 201  */
 202 void drm_bridge_remove(struct drm_bridge *bridge)
 203 {
 204         mutex_lock(&bridge_lock);
 205         list_del_init(&bridge->list);
 206         mutex_unlock(&bridge_lock);
 207
 208         mutex_destroy(&bridge->hpd_mutex);
 209 }
 210 EXPORT_SYMBOL(drm_bridge_remove);
 211
 212 static struct drm_private_state *
 213 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
 214 {
 215         struct drm_bridge *bridge = drm_priv_to_bridge(obj);
 216         struct drm_bridge_state *state;
 217
 218         state = bridge->funcs->atomic_duplicate_state(bridge);
 219         return state ? &state->base : NULL;
 220 }
 221
 222 static void
 223 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
 224                                      struct drm_private_state *s)
 225 {
 226         struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
 227         struct drm_bridge *bridge = drm_priv_to_bridge(obj);
 228
 229         bridge->funcs->atomic_destroy_state(bridge, state);
 230 }
 231
 232 static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
 233         .atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
 234         .atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
 235 };
 236
 237 /**
 238  * drm_bridge_attach - attach the bridge to an encoder's chain
 239  *
 240  * @encoder: DRM encoder
 241  * @bridge: bridge to attach
 242  * @previous: previous bridge in the chain (optional)
 243  * @flags: DRM_BRIDGE_ATTACH_* flags
 244  *
 245  * Called by a kms driver to link the bridge to an encoder's chain. The previous
 246  * argument specifies the previous bridge in the chain. If NULL, the bridge is
 247  * linked directly at the encoder's output. Otherwise it is linked at the
 248  * previous bridge's output.
 249  *
 250  * If non-NULL the previous bridge must be already attached by a call to this
 251  * function.
 252  *
 253  * Note that bridges attached to encoders are auto-detached during encoder
 254  * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
 255  * *not* be balanced with a drm_bridge_detach() in driver code.
 256  *
 257  * RETURNS:
 258  * Zero on success, error code on failure
 259  */
 260 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 261                       struct drm_bridge *previous,
 262                       enum drm_bridge_attach_flags flags)
 263 {
 264         int ret;
 265
 266         if (!encoder || !bridge)
 267                 return -EINVAL;
 268
 269         if (previous && (!previous->dev || previous->encoder != encoder))
 270                 return -EINVAL;
 271
 272         if (bridge->dev)
 273                 return -EBUSY;
 274
 275         bridge->dev = encoder->dev;
 276         bridge->encoder = encoder;
 277
 278         if (previous)
 279                 list_add(&bridge->chain_node, &previous->chain_node);
 280         else
 281                 list_add(&bridge->chain_node, &encoder->bridge_chain);
 282
 283         if (bridge->funcs->attach) {
 284                 ret = bridge->funcs->attach(bridge, flags);
 285                 if (ret < 0)
 286                         goto err_reset_bridge;
 287         }
 288
 289         if (bridge->funcs->atomic_reset) {
 290                 struct drm_bridge_state *state;
 291
 292                 state = bridge->funcs->atomic_reset(bridge);
 293                 if (IS_ERR(state)) {
 294                         ret = PTR_ERR(state);
 295                         goto err_detach_bridge;
 296                 }
 297
 298                 drm_atomic_private_obj_init(bridge->dev, &bridge->base,
 299                                             &state->base,
 300                                             &drm_bridge_priv_state_funcs);
 301         }
 302
 303         return 0;
 304
 305 err_detach_bridge:
 306         if (bridge->funcs->detach)
 307                 bridge->funcs->detach(bridge);
 308
 309 err_reset_bridge:
 310         bridge->dev = NULL;
 311         bridge->encoder = NULL;
 312         list_del(&bridge->chain_node);
 313
 314 #ifdef CONFIG_OF
 315         DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
 316                   bridge->of_node, encoder->name, ret);
 317 #else
 318         DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
 319                   encoder->name, ret);
 320 #endif
 321
 322         return ret;
 323 }
 324 EXPORT_SYMBOL(drm_bridge_attach);
 325
 326 void drm_bridge_detach(struct drm_bridge *bridge)
 327 {
 328         if (WARN_ON(!bridge))
 329                 return;
 330
 331         if (WARN_ON(!bridge->dev))
 332                 return;
 333
 334         if (bridge->funcs->atomic_reset)
 335                 drm_atomic_private_obj_fini(&bridge->base);
 336
 337         if (bridge->funcs->detach)
 338                 bridge->funcs->detach(bridge);
 339
 340         list_del(&bridge->chain_node);
 341         bridge->dev = NULL;
 342 }
 343
 344 /**
 345  * DOC: bridge operations
 346  *
 347  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
 348  * The DRM internals (atomic and CRTC helpers) use the helpers defined in
 349  * drm_bridge.c to call bridge operations. Those operations are divided in
 350  * three big categories to support different parts of the bridge usage.
 351  *
 352  * - The encoder-related operations support control of the bridges in the
 353  *   chain, and are roughly counterparts to the &drm_encoder_helper_funcs
 354  *   operations. They are used by the legacy CRTC and the atomic modeset
 355  *   helpers to perform mode validation, fixup and setting, and enable and
 356  *   disable the bridge automatically.
 357  *
 358  *   The enable and disable operations are split in
 359  *   &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
 360  *   &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
 361  *   finer-grained control.
 362  *
 363  *   Bridge drivers may implement the legacy version of those operations, or
 364  *   the atomic version (prefixed with atomic\_), in which case they shall also
 365  *   implement the atomic state bookkeeping operations
 366  *   (&drm_bridge_funcs.atomic_duplicate_state,
 367  *   &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
 368  *   Mixing atomic and non-atomic versions of the operations is not supported.
 369  *
 370  * - The bus format negotiation operations
 371  *   &drm_bridge_funcs.atomic_get_output_bus_fmts and
 372  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
 373  *   negotiate the formats transmitted between bridges in the chain when
 374  *   multiple formats are supported. Negotiation for formats is performed
 375  *   transparently for display drivers by the atomic modeset helpers. Only
 376  *   atomic versions of those operations exist, bridge drivers that need to
 377  *   implement them shall thus also implement the atomic version of the
 378  *   encoder-related operations. This feature is not supported by the legacy
 379  *   CRTC helpers.
 380  *
 381  * - The connector-related operations support implementing a &drm_connector
 382  *   based on a chain of bridges. DRM bridges traditionally create a
 383  *   &drm_connector for bridges meant to be used at the end of the chain. This
 384  *   puts additional burden on bridge drivers, especially for bridges that may
 385  *   be used in the middle of a chain or at the end of it. Furthermore, it
 386  *   requires all operations of the &drm_connector to be handled by a single
 387  *   bridge, which doesn't always match the hardware architecture.
 388  *
 389  *   To simplify bridge drivers and make the connector implementation more
 390  *   flexible, a new model allows bridges to unconditionally skip creation of
 391  *   &drm_connector and instead expose &drm_bridge_funcs operations to support
 392  *   an externally-implemented &drm_connector. Those operations are
 393  *   &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
 394  *   &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
 395  *   &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
 396  *   implemented, display drivers shall create a &drm_connector instance for
 397  *   each chain of bridges, and implement those connector instances based on
 398  *   the bridge connector operations.
 399  *
 400  *   Bridge drivers shall implement the connector-related operations for all
 401  *   the features that the bridge hardware support. For instance, if a bridge
 402  *   supports reading EDID, the &drm_bridge_funcs.get_edid shall be
 403  *   implemented. This however doesn't mean that the DDC lines are wired to the
 404  *   bridge on a particular platform, as they could also be connected to an I2C
 405  *   controller of the SoC. Support for the connector-related operations on the
 406  *   running platform is reported through the &drm_bridge.ops flags. Bridge
 407  *   drivers shall detect which operations they can support on the platform
 408  *   (usually this information is provided by ACPI or DT), and set the
 409  *   &drm_bridge.ops flags for all supported operations. A flag shall only be
 410  *   set if the corresponding &drm_bridge_funcs operation is implemented, but
 411  *   an implemented operation doesn't necessarily imply that the corresponding
 412  *   flag will be set. Display drivers shall use the &drm_bridge.ops flags to
 413  *   decide which bridge to delegate a connector operation to. This mechanism
 414  *   allows providing a single static const &drm_bridge_funcs instance in
 415  *   bridge drivers, improving security by storing function pointers in
 416  *   read-only memory.
 417  *
 418  *   In order to ease transition, bridge drivers may support both the old and
 419  *   new models by making connector creation optional and implementing the
 420  *   connected-related bridge operations. Connector creation is then controlled
 421  *   by the flags argument to the drm_bridge_attach() function. Display drivers
 422  *   that support the new model and create connectors themselves shall set the
 423  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
 424  *   connector creation. For intermediate bridges in the chain, the flag shall
 425  *   be passed to the drm_bridge_attach() call for the downstream bridge.
 426  *   Bridge drivers that implement the new model only shall return an error
 427  *   from their &drm_bridge_funcs.attach handler when the
 428  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
 429  *   should use the new model, and convert the bridge drivers they use if
 430  *   needed, in order to gradually transition to the new model.
 431  */
 432
 433 /**
 434  * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
 435  *                               encoder chain
 436  * @bridge: bridge control structure
 437  * @mode: desired mode to be set for the bridge
 438  * @adjusted_mode: updated mode that works for this bridge
 439  *
 440  * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
 441  * encoder chain, starting from the first bridge to the last.
 442  *
 443  * Note: the bridge passed should be the one closest to the encoder
 444  *
 445  * RETURNS:
 446  * true on success, false on failure
 447  */
 448 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
 449                                  const struct drm_display_mode *mode,
 450                                  struct drm_display_mode *adjusted_mode)
 451 {
 452         struct drm_encoder *encoder;
 453
 454         if (!bridge)
 455                 return true;
 456
 457         encoder = bridge->encoder;
 458         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 459                 if (!bridge->funcs->mode_fixup)
 460                         continue;
 461
 462                 if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
 463                         return false;
 464         }
 465
 466         return true;
 467 }
 468 EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
 469
 470 /**
 471  * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
 472  *                               encoder chain.
 473  * @bridge: bridge control structure
 474  * @info: display info against which the mode shall be validated
 475  * @mode: desired mode to be validated
 476  *
 477  * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
 478  * chain, starting from the first bridge to the last. If at least one bridge
 479  * does not accept the mode the function returns the error code.
 480  *
 481  * Note: the bridge passed should be the one closest to the encoder.
 482  *
 483  * RETURNS:
 484  * MODE_OK on success, drm_mode_status Enum error code on failure
 485  */
 486 enum drm_mode_status
 487 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
 488                             const struct drm_display_info *info,
 489                             const struct drm_display_mode *mode)
 490 {
 491         struct drm_encoder *encoder;
 492
 493         if (!bridge)
 494                 return MODE_OK;
 495
 496         encoder = bridge->encoder;
 497         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 498                 enum drm_mode_status ret;
 499
 500                 if (!bridge->funcs->mode_valid)
 501                         continue;
 502
 503                 ret = bridge->funcs->mode_valid(bridge, info, mode);
 504                 if (ret != MODE_OK)
 505                         return ret;
 506         }
 507
 508         return MODE_OK;
 509 }
 510 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
 511
 512 /**
 513  * drm_bridge_chain_disable - disables all bridges in the encoder chain
 514  * @bridge: bridge control structure
 515  *
 516  * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
 517  * chain, starting from the last bridge to the first. These are called before
 518  * calling the encoder's prepare op.
 519  *
 520  * Note: the bridge passed should be the one closest to the encoder
 521  */
 522 void drm_bridge_chain_disable(struct drm_bridge *bridge)
 523 {
 524         struct drm_encoder *encoder;
 525         struct drm_bridge *iter;
 526
 527         if (!bridge)
 528                 return;
 529
 530         encoder = bridge->encoder;
 531         list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
 532                 if (iter->funcs->disable)
 533                         iter->funcs->disable(iter);
 534
 535                 if (iter == bridge)
 536                         break;
 537         }
 538 }
 539 EXPORT_SYMBOL(drm_bridge_chain_disable);
 540
 541 /**
 542  * drm_bridge_chain_post_disable - cleans up after disabling all bridges in the
 543  *                                 encoder chain
 544  * @bridge: bridge control structure
 545  *
 546  * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
 547  * encoder chain, starting from the first bridge to the last. These are called
 548  * after completing the encoder's prepare op.
 549  *
 550  * Note: the bridge passed should be the one closest to the encoder
 551  */
 552 void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
 553 {
 554         struct drm_encoder *encoder;
 555
 556         if (!bridge)
 557                 return;
 558
 559         encoder = bridge->encoder;
 560         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 561                 if (bridge->funcs->post_disable)
 562                         bridge->funcs->post_disable(bridge);
 563         }
 564 }
 565 EXPORT_SYMBOL(drm_bridge_chain_post_disable);
 566
 567 /**
 568  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
 569  *                             encoder chain
 570  * @bridge: bridge control structure
 571  * @mode: desired mode to be set for the encoder chain
 572  * @adjusted_mode: updated mode that works for this encoder chain
 573  *
 574  * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
 575  * encoder chain, starting from the first bridge to the last.
 576  *
 577  * Note: the bridge passed should be the one closest to the encoder
 578  */
 579 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
 580                                const struct drm_display_mode *mode,
 581                                const struct drm_display_mode *adjusted_mode)
 582 {
 583         struct drm_encoder *encoder;
 584
 585         if (!bridge)
 586                 return;
 587
 588         encoder = bridge->encoder;
 589         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 590                 if (bridge->funcs->mode_set)
 591                         bridge->funcs->mode_set(bridge, mode, adjusted_mode);
 592         }
 593 }
 594 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
 595
 596 /**
 597  * drm_bridge_chain_pre_enable - prepares for enabling all bridges in the
 598  *                               encoder chain
 599  * @bridge: bridge control structure
 600  *
 601  * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
 602  * chain, starting from the last bridge to the first. These are called
 603  * before calling the encoder's commit op.
 604  *
 605  * Note: the bridge passed should be the one closest to the encoder
 606  */
 607 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
 608 {
 609         struct drm_encoder *encoder;
 610         struct drm_bridge *iter;
 611
 612         if (!bridge)
 613                 return;
 614
 615         encoder = bridge->encoder;
 616         list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
 617                 if (iter->funcs->pre_enable)
 618                         iter->funcs->pre_enable(iter);
 619
 620                 if (iter == bridge)
 621                         break;
 622         }
 623 }
 624 EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
 625
 626 /**
 627  * drm_bridge_chain_enable - enables all bridges in the encoder chain
 628  * @bridge: bridge control structure
 629  *
 630  * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
 631  * chain, starting from the first bridge to the last. These are called
 632  * after completing the encoder's commit op.
 633  *
 634  * Note that the bridge passed should be the one closest to the encoder
 635  */
 636 void drm_bridge_chain_enable(struct drm_bridge *bridge)
 637 {
 638         struct drm_encoder *encoder;
 639
 640         if (!bridge)
 641                 return;
 642
 643         encoder = bridge->encoder;
 644         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 645                 if (bridge->funcs->enable)
 646                         bridge->funcs->enable(bridge);
 647         }
 648 }
 649 EXPORT_SYMBOL(drm_bridge_chain_enable);
 650
 651 /**
 652  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
 653  * @bridge: bridge control structure
 654  * @old_state: old atomic state
 655  *
 656  * Calls &drm_bridge_funcs.atomic_disable (falls back on
 657  * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
 658  * starting from the last bridge to the first. These are called before calling
 659  * &drm_encoder_helper_funcs.atomic_disable
 660  *
 661  * Note: the bridge passed should be the one closest to the encoder
 662  */
 663 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
 664                                      struct drm_atomic_state *old_state)
 665 {
 666         struct drm_encoder *encoder;
 667         struct drm_bridge *iter;
 668
 669         if (!bridge)
 670                 return;
 671
 672         encoder = bridge->encoder;
 673         list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
 674                 if (iter->funcs->atomic_disable) {
 675                         struct drm_bridge_state *old_bridge_state;
 676
 677                         old_bridge_state =
 678                                 drm_atomic_get_old_bridge_state(old_state,
 679                                                                 iter);
 680                         if (WARN_ON(!old_bridge_state))
 681                                 return;
 682
 683                         iter->funcs->atomic_disable(iter, old_bridge_state);
 684                 } else if (iter->funcs->disable) {
 685                         iter->funcs->disable(iter);
 686                 }
 687
 688                 if (iter == bridge)
 689                         break;
 690         }
 691 }
 692 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
 693
 694 static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
 695                                                 struct drm_atomic_state *old_state)
 696 {
 697         if (old_state && bridge->funcs->atomic_post_disable) {
 698                 struct drm_bridge_state *old_bridge_state;
 699
 700                 old_bridge_state =
 701                         drm_atomic_get_old_bridge_state(old_state,
 702                                                         bridge);
 703                 if (WARN_ON(!old_bridge_state))
 704                         return;
 705
 706                 bridge->funcs->atomic_post_disable(bridge,
 707                                                    old_bridge_state);
 708         } else if (bridge->funcs->post_disable) {
 709                 bridge->funcs->post_disable(bridge);
 710         }
 711 }
 712
 713 /**
 714  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
 715  *                                        in the encoder chain
 716  * @bridge: bridge control structure
 717  * @old_state: old atomic state
 718  *
 719  * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
 720  * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
 721  * starting from the first bridge to the last. These are called after completing
 722  * &drm_encoder_helper_funcs.atomic_disable
 723  *
 724  * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
 725  * bridge will be called before the previous one to reverse the @pre_enable
 726  * calling direction.
 727  *
 728  * Note: the bridge passed should be the one closest to the encoder
 729  */
 730 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
 731                                           struct drm_atomic_state *old_state)
 732 {
 733         struct drm_encoder *encoder;
 734         struct drm_bridge *next, *limit;
 735
 736         if (!bridge)
 737                 return;
 738
 739         encoder = bridge->encoder;
 740
 741         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 742                 limit = NULL;
 743
 744                 if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
 745                         next = list_next_entry(bridge, chain_node);
 746
 747                         if (next->pre_enable_prev_first) {
 748                                 /* next bridge had requested that prev
 749                                  * was enabled first, so disabled last
 750                                  */
 751                                 limit = next;
 752
 753                                 /* Find the next bridge that has NOT requested
 754                                  * prev to be enabled first / disabled last
 755                                  */
 756                                 list_for_each_entry_from(next, &encoder->bridge_chain,
 757                                                          chain_node) {
 758                                         if (next->pre_enable_prev_first) {
 759                                                 next = list_prev_entry(next, chain_node);
 760                                                 limit = next;
 761                                                 break;
 762                                         }
 763                                 }
 764
 765                                 /* Call these bridges in reverse order */
 766                                 list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
 767                                                                  chain_node) {
 768                                         if (next == bridge)
 769                                                 break;
 770
 771                                         drm_atomic_bridge_call_post_disable(next,
 772                                                                             old_state);
 773                                 }
 774                         }
 775                 }
 776
 777                 drm_atomic_bridge_call_post_disable(bridge, old_state);
 778
 779                 if (limit)
 780                         /* Jump all bridges that we have already post_disabled */
 781                         bridge = limit;
 782         }
 783 }
 784 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
 785
 786 static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
 787                                               struct drm_atomic_state *old_state)
 788 {
 789         if (old_state && bridge->funcs->atomic_pre_enable) {
 790                 struct drm_bridge_state *old_bridge_state;
 791
 792                 old_bridge_state =
 793                         drm_atomic_get_old_bridge_state(old_state,
 794                                                         bridge);
 795                 if (WARN_ON(!old_bridge_state))
 796                         return;
 797
 798                 bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
 799         } else if (bridge->funcs->pre_enable) {
 800                 bridge->funcs->pre_enable(bridge);
 801         }
 802 }
 803
 804 /**
 805  * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
 806  *                                      the encoder chain
 807  * @bridge: bridge control structure
 808  * @old_state: old atomic state
 809  *
 810  * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
 811  * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
 812  * starting from the last bridge to the first. These are called before calling
 813  * &drm_encoder_helper_funcs.atomic_enable
 814  *
 815  * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
 816  * prev bridge will be called before pre_enable of this bridge.
 817  *
 818  * Note: the bridge passed should be the one closest to the encoder
 819  */
 820 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
 821                                         struct drm_atomic_state *old_state)
 822 {
 823         struct drm_encoder *encoder;
 824         struct drm_bridge *iter, *next, *limit;
 825
 826         if (!bridge)
 827                 return;
 828
 829         encoder = bridge->encoder;
 830
 831         list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
 832                 if (iter->pre_enable_prev_first) {
 833                         next = iter;
 834                         limit = bridge;
 835                         list_for_each_entry_from_reverse(next,
 836                                                          &encoder->bridge_chain,
 837                                                          chain_node) {
 838                                 if (next == bridge)
 839                                         break;
 840
 841                                 if (!next->pre_enable_prev_first) {
 842                                         /* Found first bridge that does NOT
 843                                          * request prev to be enabled first
 844                                          */
 845                                         limit = list_prev_entry(next, chain_node);
 846                                         break;
 847                                 }
 848                         }
 849
 850                         list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
 851                                 /* Call requested prev bridge pre_enable
 852                                  * in order.
 853                                  */
 854                                 if (next == iter)
 855                                         /* At the first bridge to request prev
 856                                          * bridges called first.
 857                                          */
 858                                         break;
 859
 860                                 drm_atomic_bridge_call_pre_enable(next, old_state);
 861                         }
 862                 }
 863
 864                 drm_atomic_bridge_call_pre_enable(iter, old_state);
 865
 866                 if (iter->pre_enable_prev_first)
 867                         /* Jump all bridges that we have already pre_enabled */
 868                         iter = limit;
 869
 870                 if (iter == bridge)
 871                         break;
 872         }
 873 }
 874 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
 875
 876 /**
 877  * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
 878  * @bridge: bridge control structure
 879  * @old_state: old atomic state
 880  *
 881  * Calls &drm_bridge_funcs.atomic_enable (falls back on
 882  * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
 883  * starting from the first bridge to the last. These are called after completing
 884  * &drm_encoder_helper_funcs.atomic_enable
 885  *
 886  * Note: the bridge passed should be the one closest to the encoder
 887  */
 888 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
 889                                     struct drm_atomic_state *old_state)
 890 {
 891         struct drm_encoder *encoder;
 892
 893         if (!bridge)
 894                 return;
 895
 896         encoder = bridge->encoder;
 897         list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
 898                 if (bridge->funcs->atomic_enable) {
 899                         struct drm_bridge_state *old_bridge_state;
 900
 901                         old_bridge_state =
 902                                 drm_atomic_get_old_bridge_state(old_state,
 903                                                                 bridge);
 904                         if (WARN_ON(!old_bridge_state))
 905                                 return;
 906
 907                         bridge->funcs->atomic_enable(bridge, old_bridge_state);
 908                 } else if (bridge->funcs->enable) {
 909                         bridge->funcs->enable(bridge);
 910                 }
 911         }
 912 }
 913 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
 914
 915 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
 916                                    struct drm_crtc_state *crtc_state,
 917                                    struct drm_connector_state *conn_state)
 918 {
 919         if (bridge->funcs->atomic_check) {
 920                 struct drm_bridge_state *bridge_state;
 921                 int ret;
 922
 923                 bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
 924                                                                bridge);
 925                 if (WARN_ON(!bridge_state))
 926                         return -EINVAL;
 927
 928                 ret = bridge->funcs->atomic_check(bridge, bridge_state,
 929                                                   crtc_state, conn_state);
 930                 if (ret)
 931                         return ret;
 932         } else if (bridge->funcs->mode_fixup) {
 933                 if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
 934                                                &crtc_state->adjusted_mode))
 935                         return -EINVAL;
 936         }
 937
 938         return 0;
 939 }
 940
 941 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
 942                                     struct drm_bridge *cur_bridge,
 943                                     struct drm_crtc_state *crtc_state,
 944                                     struct drm_connector_state *conn_state,
 945                                     u32 out_bus_fmt)
 946 {
 947         unsigned int i, num_in_bus_fmts = 0;
 948         struct drm_bridge_state *cur_state;
 949         struct drm_bridge *prev_bridge;
 950         u32 *in_bus_fmts;
 951         int ret;
 952
 953         prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
 954         cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
 955                                                     cur_bridge);
 956
 957         /*
 958          * If bus format negotiation is not supported by this bridge, let's
 959          * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
 960          * hope that it can handle this situation gracefully (by providing
 961          * appropriate default values).
 962          */
 963         if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
 964                 if (cur_bridge != first_bridge) {
 965                         ret = select_bus_fmt_recursive(first_bridge,
 966                                                        prev_bridge, crtc_state,
 967                                                        conn_state,
 968                                                        MEDIA_BUS_FMT_FIXED);
 969                         if (ret)
 970                                 return ret;
 971                 }
 972
 973                 /*
 974                  * Driver does not implement the atomic state hooks, but that's
 975                  * fine, as long as it does not access the bridge state.
 976                  */
 977                 if (cur_state) {
 978                         cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
 979                         cur_state->output_bus_cfg.format = out_bus_fmt;
 980                 }
 981
 982                 return 0;
 983         }
 984
 985         /*
 986          * If the driver implements ->atomic_get_input_bus_fmts() it
 987          * should also implement the atomic state hooks.
 988          */
 989         if (WARN_ON(!cur_state))
 990                 return -EINVAL;
 991
 992         in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
 993                                                         cur_state,
 994                                                         crtc_state,
 995                                                         conn_state,
 996                                                         out_bus_fmt,
 997                                                         &num_in_bus_fmts);
 998         if (!num_in_bus_fmts)
 999                 return -ENOTSUPP;
1000         else if (!in_bus_fmts)
1001                 return -ENOMEM;
1002
1003         if (first_bridge == cur_bridge) {
1004                 cur_state->input_bus_cfg.format = in_bus_fmts[0];
1005                 cur_state->output_bus_cfg.format = out_bus_fmt;
1006                 kfree(in_bus_fmts);
1007                 return 0;
1008         }
1009
1010         for (i = 0; i < num_in_bus_fmts; i++) {
1011                 ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
1012                                                crtc_state, conn_state,
1013                                                in_bus_fmts[i]);
1014                 if (ret != -ENOTSUPP)
1015                         break;
1016         }
1017
1018         if (!ret) {
1019                 cur_state->input_bus_cfg.format = in_bus_fmts[i];
1020                 cur_state->output_bus_cfg.format = out_bus_fmt;
1021         }
1022
1023         kfree(in_bus_fmts);
1024         return ret;
1025 }
1026
1027 /*
1028  * This function is called by &drm_atomic_bridge_chain_check() just before
1029  * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
1030  * It performs bus format negotiation between bridge elements. The negotiation
1031  * happens in reverse order, starting from the last element in the chain up to
1032  * @bridge.
1033  *
1034  * Negotiation starts by retrieving supported output bus formats on the last
1035  * bridge element and testing them one by one. The test is recursive, meaning
1036  * that for each tested output format, the whole chain will be walked backward,
1037  * and each element will have to choose an input bus format that can be
1038  * transcoded to the requested output format. When a bridge element does not
1039  * support transcoding into a specific output format -ENOTSUPP is returned and
1040  * the next bridge element will have to try a different format. If none of the
1041  * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
1042  *
1043  * This implementation is relying on
1044  * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
1045  * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
1046  * input/output formats.
1047  *
1048  * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
1049  * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
1050  * tries a single format: &drm_connector.display_info.bus_formats[0] if
1051  * available, MEDIA_BUS_FMT_FIXED otherwise.
1052  *
1053  * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
1054  * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
1055  * bridge element that lacks this hook and asks the previous element in the
1056  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
1057  * to do in that case (fail if they want to enforce bus format negotiation, or
1058  * provide a reasonable default if they need to support pipelines where not
1059  * all elements support bus format negotiation).
1060  */
1061 static int
1062 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
1063                                         struct drm_crtc_state *crtc_state,
1064                                         struct drm_connector_state *conn_state)
1065 {
1066         struct drm_connector *conn = conn_state->connector;
1067         struct drm_encoder *encoder = bridge->encoder;
1068         struct drm_bridge_state *last_bridge_state;
1069         unsigned int i, num_out_bus_fmts = 0;
1070         struct drm_bridge *last_bridge;
1071         u32 *out_bus_fmts;
1072         int ret = 0;
1073
1074         last_bridge = list_last_entry(&encoder->bridge_chain,
1075                                       struct drm_bridge, chain_node);
1076         last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
1077                                                             last_bridge);
1078
1079         if (last_bridge->funcs->atomic_get_output_bus_fmts) {
1080                 const struct drm_bridge_funcs *funcs = last_bridge->funcs;
1081
1082                 /*
1083                  * If the driver implements ->atomic_get_output_bus_fmts() it
1084                  * should also implement the atomic state hooks.
1085                  */
1086                 if (WARN_ON(!last_bridge_state))
1087                         return -EINVAL;
1088
1089                 out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
1090                                                         last_bridge_state,
1091                                                         crtc_state,
1092                                                         conn_state,
1093                                                         &num_out_bus_fmts);
1094                 if (!num_out_bus_fmts)
1095                         return -ENOTSUPP;
1096                 else if (!out_bus_fmts)
1097                         return -ENOMEM;
1098         } else {
1099                 num_out_bus_fmts = 1;
1100                 out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
1101                 if (!out_bus_fmts)
1102                         return -ENOMEM;
1103
1104                 if (conn->display_info.num_bus_formats &&
1105                     conn->display_info.bus_formats)
1106                         out_bus_fmts[0] = conn->display_info.bus_formats[0];
1107                 else
1108                         out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
1109         }
1110
1111         for (i = 0; i < num_out_bus_fmts; i++) {
1112                 ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
1113                                                conn_state, out_bus_fmts[i]);
1114                 if (ret != -ENOTSUPP)
1115                         break;
1116         }
1117
1118         kfree(out_bus_fmts);
1119
1120         return ret;
1121 }
1122
1123 static void
1124 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
1125                                       struct drm_connector *conn,
1126                                       struct drm_atomic_state *state)
1127 {
1128         struct drm_bridge_state *bridge_state, *next_bridge_state;
1129         struct drm_bridge *next_bridge;
1130         u32 output_flags = 0;
1131
1132         bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
1133
1134         /* No bridge state attached to this bridge => nothing to propagate. */
1135         if (!bridge_state)
1136                 return;
1137
1138         next_bridge = drm_bridge_get_next_bridge(bridge);
1139
1140         /*
1141          * Let's try to apply the most common case here, that is, propagate
1142          * display_info flags for the last bridge, and propagate the input
1143          * flags of the next bridge element to the output end of the current
1144          * bridge when the bridge is not the last one.
1145          * There are exceptions to this rule, like when signal inversion is
1146          * happening at the board level, but that's something drivers can deal
1147          * with from their &drm_bridge_funcs.atomic_check() implementation by
1148          * simply overriding the flags value we've set here.
1149          */
1150         if (!next_bridge) {
1151                 output_flags = conn->display_info.bus_flags;
1152         } else {
1153                 next_bridge_state = drm_atomic_get_new_bridge_state(state,
1154                                                                 next_bridge);
1155                 /*
1156                  * No bridge state attached to the next bridge, just leave the
1157                  * flags to 0.
1158                  */
1159                 if (next_bridge_state)
1160                         output_flags = next_bridge_state->input_bus_cfg.flags;
1161         }
1162
1163         bridge_state->output_bus_cfg.flags = output_flags;
1164
1165         /*
1166          * Propagate the output flags to the input end of the bridge. Again, it's
1167          * not necessarily what all bridges want, but that's what most of them
1168          * do, and by doing that by default we avoid forcing drivers to
1169          * duplicate the "dummy propagation" logic.
1170          */
1171         bridge_state->input_bus_cfg.flags = output_flags;
1172 }
1173
1174 /**
1175  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
1176  * @bridge: bridge control structure
1177  * @crtc_state: new CRTC state
1178  * @conn_state: new connector state
1179  *
1180  * First trigger a bus format negotiation before calling
1181  * &drm_bridge_funcs.atomic_check() (falls back on
1182  * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1183  * starting from the last bridge to the first. These are called before calling
1184  * &drm_encoder_helper_funcs.atomic_check()
1185  *
1186  * RETURNS:
1187  * 0 on success, a negative error code on failure
1188  */
1189 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1190                                   struct drm_crtc_state *crtc_state,
1191                                   struct drm_connector_state *conn_state)
1192 {
1193         struct drm_connector *conn = conn_state->connector;
1194         struct drm_encoder *encoder;
1195         struct drm_bridge *iter;
1196         int ret;
1197
1198         if (!bridge)
1199                 return 0;
1200
1201         ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1202                                                       conn_state);
1203         if (ret)
1204                 return ret;
1205
1206         encoder = bridge->encoder;
1207         list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1208                 int ret;
1209
1210                 /*
1211                  * Bus flags are propagated by default. If a bridge needs to
1212                  * tweak the input bus flags for any reason, it should happen
1213                  * in its &drm_bridge_funcs.atomic_check() implementation such
1214                  * that preceding bridges in the chain can propagate the new
1215                  * bus flags.
1216                  */
1217                 drm_atomic_bridge_propagate_bus_flags(iter, conn,
1218                                                       crtc_state->state);
1219
1220                 ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1221                 if (ret)
1222                         return ret;
1223
1224                 if (iter == bridge)
1225                         break;
1226         }
1227
1228         return 0;
1229 }
1230 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1231
1232 /**
1233  * drm_bridge_detect - check if anything is attached to the bridge output
1234  * @bridge: bridge control structure
1235  *
1236  * If the bridge supports output detection, as reported by the
1237  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1238  * bridge and return the connection status. Otherwise return
1239  * connector_status_unknown.
1240  *
1241  * RETURNS:
1242  * The detection status on success, or connector_status_unknown if the bridge
1243  * doesn't support output detection.
1244  */
1245 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1246 {
1247         if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1248                 return connector_status_unknown;
1249
1250         return bridge->funcs->detect(bridge);
1251 }
1252 EXPORT_SYMBOL_GPL(drm_bridge_detect);
1253
1254 /**
1255  * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1256  * @connector
1257  * @bridge: bridge control structure
1258  * @connector: the connector to fill with modes
1259  *
1260  * If the bridge supports output modes retrieval, as reported by the
1261  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1262  * fill the connector with all valid modes and return the number of modes
1263  * added. Otherwise return 0.
1264  *
1265  * RETURNS:
1266  * The number of modes added to the connector.
1267  */
1268 int drm_bridge_get_modes(struct drm_bridge *bridge,
1269                          struct drm_connector *connector)
1270 {
1271         if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1272                 return 0;
1273
1274         return bridge->funcs->get_modes(bridge, connector);
1275 }
1276 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1277
1278 /**
1279  * drm_bridge_get_edid - get the EDID data of the connected display
1280  * @bridge: bridge control structure
1281  * @connector: the connector to read EDID for
1282  *
1283  * If the bridge supports output EDID retrieval, as reported by the
1284  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1285  * get the EDID and return it. Otherwise return NULL.
1286  *
1287  * RETURNS:
1288  * The retrieved EDID on success, or NULL otherwise.
1289  */
1290 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1291                                  struct drm_connector *connector)
1292 {
1293         if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1294                 return NULL;
1295
1296         return bridge->funcs->get_edid(bridge, connector);
1297 }
1298 EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1299
1300 /**
1301  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1302  * @bridge: bridge control structure
1303  * @cb: hot-plug detection callback
1304  * @data: data to be passed to the hot-plug detection callback
1305  *
1306  * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1307  * and @data as hot plug notification callback. From now on the @cb will be
1308  * called with @data when an output status change is detected by the bridge,
1309  * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1310  *
1311  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1312  * bridge->ops. This function shall not be called when the flag is not set.
1313  *
1314  * Only one hot plug detection callback can be registered at a time, it is an
1315  * error to call this function when hot plug detection is already enabled for
1316  * the bridge.
1317  */
1318 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1319                            void (*cb)(void *data,
1320                                       enum drm_connector_status status),
1321                            void *data)
1322 {
1323         if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1324                 return;
1325
1326         mutex_lock(&bridge->hpd_mutex);
1327
1328         if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1329                 goto unlock;
1330
1331         bridge->hpd_cb = cb;
1332         bridge->hpd_data = data;
1333
1334         if (bridge->funcs->hpd_enable)
1335                 bridge->funcs->hpd_enable(bridge);
1336
1337 unlock:
1338         mutex_unlock(&bridge->hpd_mutex);
1339 }
1340 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1341
1342 /**
1343  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1344  * @bridge: bridge control structure
1345  *
1346  * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1347  * plug detection callback previously registered with drm_bridge_hpd_enable().
1348  * Once this function returns the callback will not be called by the bridge
1349  * when an output status change occurs.
1350  *
1351  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1352  * bridge->ops. This function shall not be called when the flag is not set.
1353  */
1354 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1355 {
1356         if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1357                 return;
1358
1359         mutex_lock(&bridge->hpd_mutex);
1360         if (bridge->funcs->hpd_disable)
1361                 bridge->funcs->hpd_disable(bridge);
1362
1363         bridge->hpd_cb = NULL;
1364         bridge->hpd_data = NULL;
1365         mutex_unlock(&bridge->hpd_mutex);
1366 }
1367 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1368
1369 /**
1370  * drm_bridge_hpd_notify - notify hot plug detection events
1371  * @bridge: bridge control structure
1372  * @status: output connection status
1373  *
1374  * Bridge drivers shall call this function to report hot plug events when they
1375  * detect a change in the output status, when hot plug detection has been
1376  * enabled by drm_bridge_hpd_enable().
1377  *
1378  * This function shall be called in a context that can sleep.
1379  */
1380 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1381                            enum drm_connector_status status)
1382 {
1383         mutex_lock(&bridge->hpd_mutex);
1384         if (bridge->hpd_cb)
1385                 bridge->hpd_cb(bridge->hpd_data, status);
1386         mutex_unlock(&bridge->hpd_mutex);
1387 }
1388 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1389
1390 #ifdef CONFIG_OF
1391 /**
1392  * of_drm_find_bridge - find the bridge corresponding to the device node in
1393  *                      the global bridge list
1394  *
1395  * @np: device node
1396  *
1397  * RETURNS:
1398  * drm_bridge control struct on success, NULL on failure
1399  */
1400 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1401 {
1402         struct drm_bridge *bridge;
1403
1404         mutex_lock(&bridge_lock);
1405
1406         list_for_each_entry(bridge, &bridge_list, list) {
1407                 if (bridge->of_node == np) {
1408                         mutex_unlock(&bridge_lock);
1409                         return bridge;
1410                 }
1411         }
1412
1413         mutex_unlock(&bridge_lock);
1414         return NULL;
1415 }
1416 EXPORT_SYMBOL(of_drm_find_bridge);
1417 #endif
1418
1419 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1420 MODULE_DESCRIPTION("DRM bridge infrastructure");
1421 MODULE_LICENSE("GPL and additional rights");