drivers/gpu/drm/drm_atomic_state_helper.c

   1 /*
   2  * Copyright (C) 2018 Intel Corp.
   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, sublicense,
   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 shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * Authors:
  23  * Rob Clark <[email protected]>
  24  * Daniel Vetter <[email protected]>
  25  */
  26
  27 #include <drm/drm_atomic.h>
  28 #include <drm/drm_atomic_state_helper.h>
  29 #include <drm/drm_bridge.h>
  30 #include <drm/drm_connector.h>
  31 #include <drm/drm_crtc.h>
  32 #include <drm/drm_device.h>
  33 #include <drm/drm_plane.h>
  34 #include <drm/drm_print.h>
  35 #include <drm/drm_writeback.h>
  36
  37 #include <linux/slab.h>
  38 #include <linux/dma-fence.h>
  39
  40 /**
  41  * DOC: atomic state reset and initialization
  42  *
  43  * Both the drm core and the atomic helpers assume that there is always the full
  44  * and correct atomic software state for all connectors, CRTCs and planes
  45  * available. Which is a bit a problem on driver load and also after system
  46  * suspend. One way to solve this is to have a hardware state read-out
  47  * infrastructure which reconstructs the full software state (e.g. the i915
  48  * driver).
  49  *
  50  * The simpler solution is to just reset the software state to everything off,
  51  * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
  52  * the atomic helpers provide default reset implementations for all hooks.
  53  *
  54  * On the upside the precise state tracking of atomic simplifies system suspend
  55  * and resume a lot. For drivers using drm_mode_config_reset() a complete recipe
  56  * is implemented in drm_atomic_helper_suspend() and drm_atomic_helper_resume().
  57  * For other drivers the building blocks are split out, see the documentation
  58  * for these functions.
  59  */
  60
  61 /**
  62  * __drm_atomic_helper_crtc_state_reset - reset the CRTC state
  63  * @crtc_state: atomic CRTC state, must not be NULL
  64  * @crtc: CRTC object, must not be NULL
  65  *
  66  * Initializes the newly allocated @crtc_state with default
  67  * values. This is useful for drivers that subclass the CRTC state.
  68  */
  69 void
  70 __drm_atomic_helper_crtc_state_reset(struct drm_crtc_state *crtc_state,
  71                                      struct drm_crtc *crtc)
  72 {
  73         crtc_state->crtc = crtc;
  74 }
  75 EXPORT_SYMBOL(__drm_atomic_helper_crtc_state_reset);
  76
  77 /**
  78  * __drm_atomic_helper_crtc_reset - reset state on CRTC
  79  * @crtc: drm CRTC
  80  * @crtc_state: CRTC state to assign
  81  *
  82  * Initializes the newly allocated @crtc_state and assigns it to
  83  * the &drm_crtc->state pointer of @crtc, usually required when
  84  * initializing the drivers or when called from the &drm_crtc_funcs.reset
  85  * hook.
  86  *
  87  * This is useful for drivers that subclass the CRTC state.
  88  */
  89 void
  90 __drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
  91                                struct drm_crtc_state *crtc_state)
  92 {
  93         if (crtc_state)
  94                 __drm_atomic_helper_crtc_state_reset(crtc_state, crtc);
  95
  96         crtc->state = crtc_state;
  97 }
  98 EXPORT_SYMBOL(__drm_atomic_helper_crtc_reset);
  99
 100 /**
 101  * drm_atomic_helper_crtc_reset - default &drm_crtc_funcs.reset hook for CRTCs
 102  * @crtc: drm CRTC
 103  *
 104  * Resets the atomic state for @crtc by freeing the state pointer (which might
 105  * be NULL, e.g. at driver load time) and allocating a new empty state object.
 106  */
 107 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
 108 {
 109         struct drm_crtc_state *crtc_state =
 110                 kzalloc(sizeof(*crtc->state), GFP_KERNEL);
 111
 112         if (crtc->state)
 113                 crtc->funcs->atomic_destroy_state(crtc, crtc->state);
 114
 115         __drm_atomic_helper_crtc_reset(crtc, crtc_state);
 116 }
 117 EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);
 118
 119 /**
 120  * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
 121  * @crtc: CRTC object
 122  * @state: atomic CRTC state
 123  *
 124  * Copies atomic state from a CRTC's current state and resets inferred values.
 125  * This is useful for drivers that subclass the CRTC state.
 126  */
 127 void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
 128                                               struct drm_crtc_state *state)
 129 {
 130         memcpy(state, crtc->state, sizeof(*state));
 131
 132         if (state->mode_blob)
 133                 drm_property_blob_get(state->mode_blob);
 134         if (state->degamma_lut)
 135                 drm_property_blob_get(state->degamma_lut);
 136         if (state->ctm)
 137                 drm_property_blob_get(state->ctm);
 138         if (state->gamma_lut)
 139                 drm_property_blob_get(state->gamma_lut);
 140         state->mode_changed = false;
 141         state->active_changed = false;
 142         state->planes_changed = false;
 143         state->connectors_changed = false;
 144         state->color_mgmt_changed = false;
 145         state->zpos_changed = false;
 146         state->commit = NULL;
 147         state->event = NULL;
 148         state->async_flip = false;
 149
 150         /* Self refresh should be canceled when a new update is available */
 151         state->active = drm_atomic_crtc_effectively_active(state);
 152         state->self_refresh_active = false;
 153 }
 154 EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);
 155
 156 /**
 157  * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
 158  * @crtc: drm CRTC
 159  *
 160  * Default CRTC state duplicate hook for drivers which don't have their own
 161  * subclassed CRTC state structure.
 162  */
 163 struct drm_crtc_state *
 164 drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
 165 {
 166         struct drm_crtc_state *state;
 167
 168         if (WARN_ON(!crtc->state))
 169                 return NULL;
 170
 171         state = kmalloc(sizeof(*state), GFP_KERNEL);
 172         if (state)
 173                 __drm_atomic_helper_crtc_duplicate_state(crtc, state);
 174
 175         return state;
 176 }
 177 EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);
 178
 179 /**
 180  * __drm_atomic_helper_crtc_destroy_state - release CRTC state
 181  * @state: CRTC state object to release
 182  *
 183  * Releases all resources stored in the CRTC state without actually freeing
 184  * the memory of the CRTC state. This is useful for drivers that subclass the
 185  * CRTC state.
 186  */
 187 void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state)
 188 {
 189         if (state->commit) {
 190                 /*
 191                  * In the event that a non-blocking commit returns
 192                  * -ERESTARTSYS before the commit_tail work is queued, we will
 193                  * have an extra reference to the commit object. Release it, if
 194                  * the event has not been consumed by the worker.
 195                  *
 196                  * state->event may be freed, so we can't directly look at
 197                  * state->event->base.completion.
 198                  */
 199                 if (state->event && state->commit->abort_completion)
 200                         drm_crtc_commit_put(state->commit);
 201
 202                 kfree(state->commit->event);
 203                 state->commit->event = NULL;
 204
 205                 drm_crtc_commit_put(state->commit);
 206         }
 207
 208         drm_property_blob_put(state->mode_blob);
 209         drm_property_blob_put(state->degamma_lut);
 210         drm_property_blob_put(state->ctm);
 211         drm_property_blob_put(state->gamma_lut);
 212 }
 213 EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);
 214
 215 /**
 216  * drm_atomic_helper_crtc_destroy_state - default state destroy hook
 217  * @crtc: drm CRTC
 218  * @state: CRTC state object to release
 219  *
 220  * Default CRTC state destroy hook for drivers which don't have their own
 221  * subclassed CRTC state structure.
 222  */
 223 void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
 224                                           struct drm_crtc_state *state)
 225 {
 226         __drm_atomic_helper_crtc_destroy_state(state);
 227         kfree(state);
 228 }
 229 EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);
 230
 231 /**
 232  * __drm_atomic_helper_plane_state_reset - resets plane state to default values
 233  * @plane_state: atomic plane state, must not be NULL
 234  * @plane: plane object, must not be NULL
 235  *
 236  * Initializes the newly allocated @plane_state with default
 237  * values. This is useful for drivers that subclass the CRTC state.
 238  */
 239 void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,
 240                                            struct drm_plane *plane)
 241 {
 242         plane_state->plane = plane;
 243         plane_state->rotation = DRM_MODE_ROTATE_0;
 244
 245         plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
 246         plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
 247 }
 248 EXPORT_SYMBOL(__drm_atomic_helper_plane_state_reset);
 249
 250 /**
 251  * __drm_atomic_helper_plane_reset - reset state on plane
 252  * @plane: drm plane
 253  * @plane_state: plane state to assign
 254  *
 255  * Initializes the newly allocated @plane_state and assigns it to
 256  * the &drm_crtc->state pointer of @plane, usually required when
 257  * initializing the drivers or when called from the &drm_plane_funcs.reset
 258  * hook.
 259  *
 260  * This is useful for drivers that subclass the plane state.
 261  */
 262 void __drm_atomic_helper_plane_reset(struct drm_plane *plane,
 263                                      struct drm_plane_state *plane_state)
 264 {
 265         if (plane_state)
 266                 __drm_atomic_helper_plane_state_reset(plane_state, plane);
 267
 268         plane->state = plane_state;
 269 }
 270 EXPORT_SYMBOL(__drm_atomic_helper_plane_reset);
 271
 272 /**
 273  * drm_atomic_helper_plane_reset - default &drm_plane_funcs.reset hook for planes
 274  * @plane: drm plane
 275  *
 276  * Resets the atomic state for @plane by freeing the state pointer (which might
 277  * be NULL, e.g. at driver load time) and allocating a new empty state object.
 278  */
 279 void drm_atomic_helper_plane_reset(struct drm_plane *plane)
 280 {
 281         if (plane->state)
 282                 __drm_atomic_helper_plane_destroy_state(plane->state);
 283
 284         kfree(plane->state);
 285         plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);
 286         if (plane->state)
 287                 __drm_atomic_helper_plane_reset(plane, plane->state);
 288 }
 289 EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
 290
 291 /**
 292  * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
 293  * @plane: plane object
 294  * @state: atomic plane state
 295  *
 296  * Copies atomic state from a plane's current state. This is useful for
 297  * drivers that subclass the plane state.
 298  */
 299 void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
 300                                                struct drm_plane_state *state)
 301 {
 302         memcpy(state, plane->state, sizeof(*state));
 303
 304         if (state->fb)
 305                 drm_framebuffer_get(state->fb);
 306
 307         state->fence = NULL;
 308         state->commit = NULL;
 309         state->fb_damage_clips = NULL;
 310 }
 311 EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);
 312
 313 /**
 314  * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
 315  * @plane: drm plane
 316  *
 317  * Default plane state duplicate hook for drivers which don't have their own
 318  * subclassed plane state structure.
 319  */
 320 struct drm_plane_state *
 321 drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
 322 {
 323         struct drm_plane_state *state;
 324
 325         if (WARN_ON(!plane->state))
 326                 return NULL;
 327
 328         state = kmalloc(sizeof(*state), GFP_KERNEL);
 329         if (state)
 330                 __drm_atomic_helper_plane_duplicate_state(plane, state);
 331
 332         return state;
 333 }
 334 EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);
 335
 336 /**
 337  * __drm_atomic_helper_plane_destroy_state - release plane state
 338  * @state: plane state object to release
 339  *
 340  * Releases all resources stored in the plane state without actually freeing
 341  * the memory of the plane state. This is useful for drivers that subclass the
 342  * plane state.
 343  */
 344 void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
 345 {
 346         if (state->fb)
 347                 drm_framebuffer_put(state->fb);
 348
 349         if (state->fence)
 350                 dma_fence_put(state->fence);
 351
 352         if (state->commit)
 353                 drm_crtc_commit_put(state->commit);
 354
 355         drm_property_blob_put(state->fb_damage_clips);
 356 }
 357 EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
 358
 359 /**
 360  * drm_atomic_helper_plane_destroy_state - default state destroy hook
 361  * @plane: drm plane
 362  * @state: plane state object to release
 363  *
 364  * Default plane state destroy hook for drivers which don't have their own
 365  * subclassed plane state structure.
 366  */
 367 void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
 368                                            struct drm_plane_state *state)
 369 {
 370         __drm_atomic_helper_plane_destroy_state(state);
 371         kfree(state);
 372 }
 373 EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);
 374
 375 /**
 376  * __drm_atomic_helper_connector_state_reset - reset the connector state
 377  * @conn_state: atomic connector state, must not be NULL
 378  * @connector: connectotr object, must not be NULL
 379  *
 380  * Initializes the newly allocated @conn_state with default
 381  * values. This is useful for drivers that subclass the connector state.
 382  */
 383 void
 384 __drm_atomic_helper_connector_state_reset(struct drm_connector_state *conn_state,
 385                                           struct drm_connector *connector)
 386 {
 387         conn_state->connector = connector;
 388 }
 389 EXPORT_SYMBOL(__drm_atomic_helper_connector_state_reset);
 390
 391 /**
 392  * __drm_atomic_helper_connector_reset - reset state on connector
 393  * @connector: drm connector
 394  * @conn_state: connector state to assign
 395  *
 396  * Initializes the newly allocated @conn_state and assigns it to
 397  * the &drm_connector->state pointer of @connector, usually required when
 398  * initializing the drivers or when called from the &drm_connector_funcs.reset
 399  * hook.
 400  *
 401  * This is useful for drivers that subclass the connector state.
 402  */
 403 void
 404 __drm_atomic_helper_connector_reset(struct drm_connector *connector,
 405                                     struct drm_connector_state *conn_state)
 406 {
 407         if (conn_state)
 408                 __drm_atomic_helper_connector_state_reset(conn_state, connector);
 409
 410         connector->state = conn_state;
 411 }
 412 EXPORT_SYMBOL(__drm_atomic_helper_connector_reset);
 413
 414 /**
 415  * drm_atomic_helper_connector_reset - default &drm_connector_funcs.reset hook for connectors
 416  * @connector: drm connector
 417  *
 418  * Resets the atomic state for @connector by freeing the state pointer (which
 419  * might be NULL, e.g. at driver load time) and allocating a new empty state
 420  * object.
 421  */
 422 void drm_atomic_helper_connector_reset(struct drm_connector *connector)
 423 {
 424         struct drm_connector_state *conn_state =
 425                 kzalloc(sizeof(*conn_state), GFP_KERNEL);
 426
 427         if (connector->state)
 428                 __drm_atomic_helper_connector_destroy_state(connector->state);
 429
 430         kfree(connector->state);
 431         __drm_atomic_helper_connector_reset(connector, conn_state);
 432 }
 433 EXPORT_SYMBOL(drm_atomic_helper_connector_reset);
 434
 435 /**
 436  * drm_atomic_helper_connector_tv_reset - Resets TV connector properties
 437  * @connector: DRM connector
 438  *
 439  * Resets the TV-related properties attached to a connector.
 440  */
 441 void drm_atomic_helper_connector_tv_reset(struct drm_connector *connector)
 442 {
 443         struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
 444         struct drm_connector_state *state = connector->state;
 445
 446         state->tv.margins.left = cmdline->tv_margins.left;
 447         state->tv.margins.right = cmdline->tv_margins.right;
 448         state->tv.margins.top = cmdline->tv_margins.top;
 449         state->tv.margins.bottom = cmdline->tv_margins.bottom;
 450 }
 451 EXPORT_SYMBOL(drm_atomic_helper_connector_tv_reset);
 452
 453 /**
 454  * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
 455  * @connector: connector object
 456  * @state: atomic connector state
 457  *
 458  * Copies atomic state from a connector's current state. This is useful for
 459  * drivers that subclass the connector state.
 460  */
 461 void
 462 __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
 463                                             struct drm_connector_state *state)
 464 {
 465         memcpy(state, connector->state, sizeof(*state));
 466         if (state->crtc)
 467                 drm_connector_get(connector);
 468         state->commit = NULL;
 469
 470         if (state->hdr_output_metadata)
 471                 drm_property_blob_get(state->hdr_output_metadata);
 472
 473         /* Don't copy over a writeback job, they are used only once */
 474         state->writeback_job = NULL;
 475 }
 476 EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);
 477
 478 /**
 479  * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
 480  * @connector: drm connector
 481  *
 482  * Default connector state duplicate hook for drivers which don't have their own
 483  * subclassed connector state structure.
 484  */
 485 struct drm_connector_state *
 486 drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
 487 {
 488         struct drm_connector_state *state;
 489
 490         if (WARN_ON(!connector->state))
 491                 return NULL;
 492
 493         state = kmalloc(sizeof(*state), GFP_KERNEL);
 494         if (state)
 495                 __drm_atomic_helper_connector_duplicate_state(connector, state);
 496
 497         return state;
 498 }
 499 EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);
 500
 501 /**
 502  * __drm_atomic_helper_connector_destroy_state - release connector state
 503  * @state: connector state object to release
 504  *
 505  * Releases all resources stored in the connector state without actually
 506  * freeing the memory of the connector state. This is useful for drivers that
 507  * subclass the connector state.
 508  */
 509 void
 510 __drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
 511 {
 512         if (state->crtc)
 513                 drm_connector_put(state->connector);
 514
 515         if (state->commit)
 516                 drm_crtc_commit_put(state->commit);
 517
 518         if (state->writeback_job)
 519                 drm_writeback_cleanup_job(state->writeback_job);
 520
 521         drm_property_blob_put(state->hdr_output_metadata);
 522 }
 523 EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);
 524
 525 /**
 526  * drm_atomic_helper_connector_destroy_state - default state destroy hook
 527  * @connector: drm connector
 528  * @state: connector state object to release
 529  *
 530  * Default connector state destroy hook for drivers which don't have their own
 531  * subclassed connector state structure.
 532  */
 533 void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
 534                                           struct drm_connector_state *state)
 535 {
 536         __drm_atomic_helper_connector_destroy_state(state);
 537         kfree(state);
 538 }
 539 EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
 540
 541 /**
 542  * __drm_atomic_helper_private_duplicate_state - copy atomic private state
 543  * @obj: CRTC object
 544  * @state: new private object state
 545  *
 546  * Copies atomic state from a private objects's current state and resets inferred values.
 547  * This is useful for drivers that subclass the private state.
 548  */
 549 void __drm_atomic_helper_private_obj_duplicate_state(struct drm_private_obj *obj,
 550                                                      struct drm_private_state *state)
 551 {
 552         memcpy(state, obj->state, sizeof(*state));
 553 }
 554 EXPORT_SYMBOL(__drm_atomic_helper_private_obj_duplicate_state);
 555
 556 /**
 557  * __drm_atomic_helper_bridge_duplicate_state() - Copy atomic bridge state
 558  * @bridge: bridge object
 559  * @state: atomic bridge state
 560  *
 561  * Copies atomic state from a bridge's current state and resets inferred values.
 562  * This is useful for drivers that subclass the bridge state.
 563  */
 564 void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge,
 565                                                 struct drm_bridge_state *state)
 566 {
 567         __drm_atomic_helper_private_obj_duplicate_state(&bridge->base,
 568                                                         &state->base);
 569         state->bridge = bridge;
 570 }
 571 EXPORT_SYMBOL(__drm_atomic_helper_bridge_duplicate_state);
 572
 573 /**
 574  * drm_atomic_helper_bridge_duplicate_state() - Duplicate a bridge state object
 575  * @bridge: bridge object
 576  *
 577  * Allocates a new bridge state and initializes it with the current bridge
 578  * state values. This helper is meant to be used as a bridge
 579  * &drm_bridge_funcs.atomic_duplicate_state hook for bridges that don't
 580  * subclass the bridge state.
 581  */
 582 struct drm_bridge_state *
 583 drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge)
 584 {
 585         struct drm_bridge_state *new;
 586
 587         if (WARN_ON(!bridge->base.state))
 588                 return NULL;
 589
 590         new = kzalloc(sizeof(*new), GFP_KERNEL);
 591         if (new)
 592                 __drm_atomic_helper_bridge_duplicate_state(bridge, new);
 593
 594         return new;
 595 }
 596 EXPORT_SYMBOL(drm_atomic_helper_bridge_duplicate_state);
 597
 598 /**
 599  * drm_atomic_helper_bridge_destroy_state() - Destroy a bridge state object
 600  * @bridge: the bridge this state refers to
 601  * @state: bridge state to destroy
 602  *
 603  * Destroys a bridge state previously created by
 604  * &drm_atomic_helper_bridge_reset() or
 605  * &drm_atomic_helper_bridge_duplicate_state(). This helper is meant to be
 606  * used as a bridge &drm_bridge_funcs.atomic_destroy_state hook for bridges
 607  * that don't subclass the bridge state.
 608  */
 609 void drm_atomic_helper_bridge_destroy_state(struct drm_bridge *bridge,
 610                                             struct drm_bridge_state *state)
 611 {
 612         kfree(state);
 613 }
 614 EXPORT_SYMBOL(drm_atomic_helper_bridge_destroy_state);
 615
 616 /**
 617  * __drm_atomic_helper_bridge_reset() - Initialize a bridge state to its
 618  *                                      default
 619  * @bridge: the bridge this state refers to
 620  * @state: bridge state to initialize
 621  *
 622  * Initializes the bridge state to default values. This is meant to be called
 623  * by the bridge &drm_bridge_funcs.atomic_reset hook for bridges that subclass
 624  * the bridge state.
 625  */
 626 void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge,
 627                                       struct drm_bridge_state *state)
 628 {
 629         memset(state, 0, sizeof(*state));
 630         state->bridge = bridge;
 631 }
 632 EXPORT_SYMBOL(__drm_atomic_helper_bridge_reset);
 633
 634 /**
 635  * drm_atomic_helper_bridge_reset() - Allocate and initialize a bridge state
 636  *                                    to its default
 637  * @bridge: the bridge this state refers to
 638  *
 639  * Allocates the bridge state and initializes it to default values. This helper
 640  * is meant to be used as a bridge &drm_bridge_funcs.atomic_reset hook for
 641  * bridges that don't subclass the bridge state.
 642  */
 643 struct drm_bridge_state *
 644 drm_atomic_helper_bridge_reset(struct drm_bridge *bridge)
 645 {
 646         struct drm_bridge_state *bridge_state;
 647
 648         bridge_state = kzalloc(sizeof(*bridge_state), GFP_KERNEL);
 649         if (!bridge_state)
 650                 return ERR_PTR(-ENOMEM);
 651
 652         __drm_atomic_helper_bridge_reset(bridge, bridge_state);
 653         return bridge_state;
 654 }
 655 EXPORT_SYMBOL(drm_atomic_helper_bridge_reset);