drivers/gpu/drm/drm_atomic.c

   1 /*
   2  * Copyright (C) 2014 Red Hat
   3  * Copyright (C) 2014 Intel Corp.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions 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 NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  19  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  20  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  21  * OTHER DEALINGS IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  * Rob Clark <robdclark@gmail.com>
  25  * Daniel Vetter <daniel.vetter@ffwll.ch>
  26  */
  27
  28
  29 #include <drm/drmP.h>
  30 #include <drm/drm_atomic.h>
  31 #include <drm/drm_plane_helper.h>
  32
  33 static void kfree_state(struct drm_atomic_state *state)
  34 {
  35         kfree(state->connectors);
  36         kfree(state->connector_states);
  37         kfree(state->crtcs);
  38         kfree(state->crtc_states);
  39         kfree(state->planes);
  40         kfree(state->plane_states);
  41         kfree(state);
  42 }
  43
  44 /**
  45  * drm_atomic_state_alloc - allocate atomic state
  46  * @dev: DRM device
  47  *
  48  * This allocates an empty atomic state to track updates.
  49  */
  50 struct drm_atomic_state *
  51 drm_atomic_state_alloc(struct drm_device *dev)
  52 {
  53         struct drm_atomic_state *state;
  54
  55         state = kzalloc(sizeof(*state), GFP_KERNEL);
  56         if (!state)
  57                 return NULL;
  58
  59         state->num_connector = ACCESS_ONCE(dev->mode_config.num_connector);
  60
  61         state->crtcs = kcalloc(dev->mode_config.num_crtc,
  62                                sizeof(*state->crtcs), GFP_KERNEL);
  63         if (!state->crtcs)
  64                 goto fail;
  65         state->crtc_states = kcalloc(dev->mode_config.num_crtc,
  66                                      sizeof(*state->crtc_states), GFP_KERNEL);
  67         if (!state->crtc_states)
  68                 goto fail;
  69         state->planes = kcalloc(dev->mode_config.num_total_plane,
  70                                 sizeof(*state->planes), GFP_KERNEL);
  71         if (!state->planes)
  72                 goto fail;
  73         state->plane_states = kcalloc(dev->mode_config.num_total_plane,
  74                                       sizeof(*state->plane_states), GFP_KERNEL);
  75         if (!state->plane_states)
  76                 goto fail;
  77         state->connectors = kcalloc(state->num_connector,
  78                                     sizeof(*state->connectors),
  79                                     GFP_KERNEL);
  80         if (!state->connectors)
  81                 goto fail;
  82         state->connector_states = kcalloc(state->num_connector,
  83                                           sizeof(*state->connector_states),
  84                                           GFP_KERNEL);
  85         if (!state->connector_states)
  86                 goto fail;
  87
  88         state->dev = dev;
  89
  90         DRM_DEBUG_KMS("Allocate atomic state %p\n", state);
  91
  92         return state;
  93 fail:
  94         kfree_state(state);
  95
  96         return NULL;
  97 }
  98 EXPORT_SYMBOL(drm_atomic_state_alloc);
  99
 100 /**
 101  * drm_atomic_state_clear - clear state object
 102  * @state: atomic state
 103  *
 104  * When the w/w mutex algorithm detects a deadlock we need to back off and drop
 105  * all locks. So someone else could sneak in and change the current modeset
 106  * configuration. Which means that all the state assembled in @state is no
 107  * longer an atomic update to the current state, but to some arbitrary earlier
 108  * state. Which could break assumptions the driver's ->atomic_check likely
 109  * relies on.
 110  *
 111  * Hence we must clear all cached state and completely start over, using this
 112  * function.
 113  */
 114 void drm_atomic_state_clear(struct drm_atomic_state *state)
 115 {
 116         struct drm_device *dev = state->dev;
 117         struct drm_mode_config *config = &dev->mode_config;
 118         int i;
 119
 120         DRM_DEBUG_KMS("Clearing atomic state %p\n", state);
 121
 122         for (i = 0; i < state->num_connector; i++) {
 123                 struct drm_connector *connector = state->connectors[i];
 124
 125                 if (!connector)
 126                         continue;
 127
 128                 WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
 129
 130                 connector->funcs->atomic_destroy_state(connector,
 131                                                        state->connector_states[i]);
 132         }
 133
 134         for (i = 0; i < config->num_crtc; i++) {
 135                 struct drm_crtc *crtc = state->crtcs[i];
 136
 137                 if (!crtc)
 138                         continue;
 139
 140                 crtc->funcs->atomic_destroy_state(crtc,
 141                                                   state->crtc_states[i]);
 142         }
 143
 144         for (i = 0; i < config->num_total_plane; i++) {
 145                 struct drm_plane *plane = state->planes[i];
 146
 147                 if (!plane)
 148                         continue;
 149
 150                 plane->funcs->atomic_destroy_state(plane,
 151                                                    state->plane_states[i]);
 152         }
 153 }
 154 EXPORT_SYMBOL(drm_atomic_state_clear);
 155
 156 /**
 157  * drm_atomic_state_free - free all memory for an atomic state
 158  * @state: atomic state to deallocate
 159  *
 160  * This frees all memory associated with an atomic state, including all the
 161  * per-object state for planes, crtcs and connectors.
 162  */
 163 void drm_atomic_state_free(struct drm_atomic_state *state)
 164 {
 165         drm_atomic_state_clear(state);
 166
 167         DRM_DEBUG_KMS("Freeing atomic state %p\n", state);
 168
 169         kfree_state(state);
 170 }
 171 EXPORT_SYMBOL(drm_atomic_state_free);
 172
 173 /**
 174  * drm_atomic_get_crtc_state - get crtc state
 175  * @state: global atomic state object
 176  * @crtc: crtc to get state object for
 177  *
 178  * This function returns the crtc state for the given crtc, allocating it if
 179  * needed. It will also grab the relevant crtc lock to make sure that the state
 180  * is consistent.
 181  *
 182  * Returns:
 183  *
 184  * Either the allocated state or the error code encoded into the pointer. When
 185  * the error is EDEADLK then the w/w mutex code has detected a deadlock and the
 186  * entire atomic sequence must be restarted. All other errors are fatal.
 187  */
 188 struct drm_crtc_state *
 189 drm_atomic_get_crtc_state(struct drm_atomic_state *state,
 190                           struct drm_crtc *crtc)
 191 {
 192         int ret, index;
 193         struct drm_crtc_state *crtc_state;
 194
 195         index = drm_crtc_index(crtc);
 196
 197         if (state->crtc_states[index])
 198                 return state->crtc_states[index];
 199
 200         ret = drm_modeset_lock(&crtc->mutex, state->acquire_ctx);
 201         if (ret)
 202                 return ERR_PTR(ret);
 203
 204         crtc_state = crtc->funcs->atomic_duplicate_state(crtc);
 205         if (!crtc_state)
 206                 return ERR_PTR(-ENOMEM);
 207
 208         state->crtc_states[index] = crtc_state;
 209         state->crtcs[index] = crtc;
 210         crtc_state->state = state;
 211
 212         DRM_DEBUG_KMS("Added [CRTC:%d] %p state to %p\n",
 213                       crtc->base.id, crtc_state, state);
 214
 215         return crtc_state;
 216 }
 217 EXPORT_SYMBOL(drm_atomic_get_crtc_state);
 218
 219 /**
 220  * drm_atomic_get_plane_state - get plane state
 221  * @state: global atomic state object
 222  * @plane: plane to get state object for
 223  *
 224  * This function returns the plane state for the given plane, allocating it if
 225  * needed. It will also grab the relevant plane lock to make sure that the state
 226  * is consistent.
 227  *
 228  * Returns:
 229  *
 230  * Either the allocated state or the error code encoded into the pointer. When
 231  * the error is EDEADLK then the w/w mutex code has detected a deadlock and the
 232  * entire atomic sequence must be restarted. All other errors are fatal.
 233  */
 234 struct drm_plane_state *
 235 drm_atomic_get_plane_state(struct drm_atomic_state *state,
 236                           struct drm_plane *plane)
 237 {
 238         int ret, index;
 239         struct drm_plane_state *plane_state;
 240
 241         index = drm_plane_index(plane);
 242
 243         if (state->plane_states[index])
 244                 return state->plane_states[index];
 245
 246         ret = drm_modeset_lock(&plane->mutex, state->acquire_ctx);
 247         if (ret)
 248                 return ERR_PTR(ret);
 249
 250         plane_state = plane->funcs->atomic_duplicate_state(plane);
 251         if (!plane_state)
 252                 return ERR_PTR(-ENOMEM);
 253
 254         state->plane_states[index] = plane_state;
 255         state->planes[index] = plane;
 256         plane_state->state = state;
 257
 258         DRM_DEBUG_KMS("Added [PLANE:%d] %p state to %p\n",
 259                       plane->base.id, plane_state, state);
 260
 261         if (plane_state->crtc) {
 262                 struct drm_crtc_state *crtc_state;
 263
 264                 crtc_state = drm_atomic_get_crtc_state(state,
 265                                                        plane_state->crtc);
 266                 if (IS_ERR(crtc_state))
 267                         return ERR_CAST(crtc_state);
 268         }
 269
 270         return plane_state;
 271 }
 272 EXPORT_SYMBOL(drm_atomic_get_plane_state);
 273
 274 /**
 275  * drm_atomic_get_connector_state - get connector state
 276  * @state: global atomic state object
 277  * @connector: connector to get state object for
 278  *
 279  * This function returns the connector state for the given connector,
 280  * allocating it if needed. It will also grab the relevant connector lock to
 281  * make sure that the state is consistent.
 282  *
 283  * Returns:
 284  *
 285  * Either the allocated state or the error code encoded into the pointer. When
 286  * the error is EDEADLK then the w/w mutex code has detected a deadlock and the
 287  * entire atomic sequence must be restarted. All other errors are fatal.
 288  */
 289 struct drm_connector_state *
 290 drm_atomic_get_connector_state(struct drm_atomic_state *state,
 291                           struct drm_connector *connector)
 292 {
 293         int ret, index;
 294         struct drm_mode_config *config = &connector->dev->mode_config;
 295         struct drm_connector_state *connector_state;
 296
 297         ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
 298         if (ret)
 299                 return ERR_PTR(ret);
 300
 301         index = drm_connector_index(connector);
 302
 303         /*
 304          * Construction of atomic state updates can race with a connector
 305          * hot-add which might overflow. In this case flip the table and just
 306          * restart the entire ioctl - no one is fast enough to livelock a cpu
 307          * with physical hotplug events anyway.
 308          *
 309          * Note that we only grab the indexes once we have the right lock to
 310          * prevent hotplug/unplugging of connectors. So removal is no problem,
 311          * at most the array is a bit too large.
 312          */
 313         if (index >= state->num_connector) {
 314                 DRM_DEBUG_KMS("Hot-added connector would overflow state array, restarting\n");
 315                 return ERR_PTR(-EAGAIN);
 316         }
 317
 318         if (state->connector_states[index])
 319                 return state->connector_states[index];
 320
 321         connector_state = connector->funcs->atomic_duplicate_state(connector);
 322         if (!connector_state)
 323                 return ERR_PTR(-ENOMEM);
 324
 325         state->connector_states[index] = connector_state;
 326         state->connectors[index] = connector;
 327         connector_state->state = state;
 328
 329         DRM_DEBUG_KMS("Added [CONNECTOR:%d] %p state to %p\n",
 330                       connector->base.id, connector_state, state);
 331
 332         if (connector_state->crtc) {
 333                 struct drm_crtc_state *crtc_state;
 334
 335                 crtc_state = drm_atomic_get_crtc_state(state,
 336                                                        connector_state->crtc);
 337                 if (IS_ERR(crtc_state))
 338                         return ERR_CAST(crtc_state);
 339         }
 340
 341         return connector_state;
 342 }
 343 EXPORT_SYMBOL(drm_atomic_get_connector_state);
 344
 345 /**
 346  * drm_atomic_set_crtc_for_plane - set crtc for plane
 347  * @plane_state: the plane whose incoming state to update
 348  * @crtc: crtc to use for the plane
 349  *
 350  * Changing the assigned crtc for a plane requires us to grab the lock and state
 351  * for the new crtc, as needed. This function takes care of all these details
 352  * besides updating the pointer in the state object itself.
 353  *
 354  * Returns:
 355  * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
 356  * then the w/w mutex code has detected a deadlock and the entire atomic
 357  * sequence must be restarted. All other errors are fatal.
 358  */
 359 int
 360 drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
 361                               struct drm_crtc *crtc)
 362 {
 363         struct drm_plane *plane = plane_state->plane;
 364         struct drm_crtc_state *crtc_state;
 365
 366         if (plane_state->crtc) {
 367                 crtc_state = drm_atomic_get_crtc_state(plane_state->state,
 368                                                        plane_state->crtc);
 369                 if (WARN_ON(IS_ERR(crtc_state)))
 370                         return PTR_ERR(crtc_state);
 371
 372                 crtc_state->plane_mask &= ~(1 << drm_plane_index(plane));
 373         }
 374
 375         plane_state->crtc = crtc;
 376
 377         if (crtc) {
 378                 crtc_state = drm_atomic_get_crtc_state(plane_state->state,
 379                                                        crtc);
 380                 if (IS_ERR(crtc_state))
 381                         return PTR_ERR(crtc_state);
 382                 crtc_state->plane_mask |= (1 << drm_plane_index(plane));
 383         }
 384
 385         if (crtc)
 386                 DRM_DEBUG_KMS("Link plane state %p to [CRTC:%d]\n",
 387                               plane_state, crtc->base.id);
 388         else
 389                 DRM_DEBUG_KMS("Link plane state %p to [NOCRTC]\n", plane_state);
 390
 391         return 0;
 392 }
 393 EXPORT_SYMBOL(drm_atomic_set_crtc_for_plane);
 394
 395 /**
 396  * drm_atomic_set_fb_for_plane - set crtc for plane
 397  * @plane_state: atomic state object for the plane
 398  * @fb: fb to use for the plane
 399  *
 400  * Changing the assigned framebuffer for a plane requires us to grab a reference
 401  * to the new fb and drop the reference to the old fb, if there is one. This
 402  * function takes care of all these details besides updating the pointer in the
 403  * state object itself.
 404  */
 405 void
 406 drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
 407                             struct drm_framebuffer *fb)
 408 {
 409         if (plane_state->fb)
 410                 drm_framebuffer_unreference(plane_state->fb);
 411         if (fb)
 412                 drm_framebuffer_reference(fb);
 413         plane_state->fb = fb;
 414
 415         if (fb)
 416                 DRM_DEBUG_KMS("Set [FB:%d] for plane state %p\n",
 417                               fb->base.id, plane_state);
 418         else
 419                 DRM_DEBUG_KMS("Set [NOFB] for plane state %p\n", plane_state);
 420 }
 421 EXPORT_SYMBOL(drm_atomic_set_fb_for_plane);
 422
 423 /**
 424  * drm_atomic_set_crtc_for_connector - set crtc for connector
 425  * @conn_state: atomic state object for the connector
 426  * @crtc: crtc to use for the connector
 427  *
 428  * Changing the assigned crtc for a connector requires us to grab the lock and
 429  * state for the new crtc, as needed. This function takes care of all these
 430  * details besides updating the pointer in the state object itself.
 431  *
 432  * Returns:
 433  * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
 434  * then the w/w mutex code has detected a deadlock and the entire atomic
 435  * sequence must be restarted. All other errors are fatal.
 436  */
 437 int
 438 drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
 439                                   struct drm_crtc *crtc)
 440 {
 441         struct drm_crtc_state *crtc_state;
 442
 443         if (crtc) {
 444                 crtc_state = drm_atomic_get_crtc_state(conn_state->state, crtc);
 445                 if (IS_ERR(crtc_state))
 446                         return PTR_ERR(crtc_state);
 447         }
 448
 449         conn_state->crtc = crtc;
 450
 451         if (crtc)
 452                 DRM_DEBUG_KMS("Link connector state %p to [CRTC:%d]\n",
 453                               conn_state, crtc->base.id);
 454         else
 455                 DRM_DEBUG_KMS("Link connector state %p to [NOCRTC]\n",
 456                               conn_state);
 457
 458         return 0;
 459 }
 460 EXPORT_SYMBOL(drm_atomic_set_crtc_for_connector);
 461
 462 /**
 463  * drm_atomic_add_affected_connectors - add connectors for crtc
 464  * @state: atomic state
 465  * @crtc: DRM crtc
 466  *
 467  * This function walks the current configuration and adds all connectors
 468  * currently using @crtc to the atomic configuration @state. Note that this
 469  * function must acquire the connection mutex. This can potentially cause
 470  * unneeded seralization if the update is just for the planes on one crtc. Hence
 471  * drivers and helpers should only call this when really needed (e.g. when a
 472  * full modeset needs to happen due to some change).
 473  *
 474  * Returns:
 475  * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
 476  * then the w/w mutex code has detected a deadlock and the entire atomic
 477  * sequence must be restarted. All other errors are fatal.
 478  */
 479 int
 480 drm_atomic_add_affected_connectors(struct drm_atomic_state *state,
 481                                    struct drm_crtc *crtc)
 482 {
 483         struct drm_mode_config *config = &state->dev->mode_config;
 484         struct drm_connector *connector;
 485         struct drm_connector_state *conn_state;
 486         int ret;
 487
 488         ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
 489         if (ret)
 490                 return ret;
 491
 492         DRM_DEBUG_KMS("Adding all current connectors for [CRTC:%d] to %p\n",
 493                       crtc->base.id, state);
 494
 495         /*
 496          * Changed connectors are already in @state, so only need to look at the
 497          * current configuration.
 498          */
 499         list_for_each_entry(connector, &config->connector_list, head) {
 500                 if (connector->state->crtc != crtc)
 501                         continue;
 502
 503                 conn_state = drm_atomic_get_connector_state(state, connector);
 504                 if (IS_ERR(conn_state))
 505                         return PTR_ERR(conn_state);
 506         }
 507
 508         return 0;
 509 }
 510 EXPORT_SYMBOL(drm_atomic_add_affected_connectors);
 511
 512 /**
 513  * drm_atomic_connectors_for_crtc - count number of connected outputs
 514  * @state: atomic state
 515  * @crtc: DRM crtc
 516  *
 517  * This function counts all connectors which will be connected to @crtc
 518  * according to @state. Useful to recompute the enable state for @crtc.
 519  */
 520 int
 521 drm_atomic_connectors_for_crtc(struct drm_atomic_state *state,
 522                                struct drm_crtc *crtc)
 523 {
 524         int i, num_connected_connectors = 0;
 525
 526         for (i = 0; i < state->num_connector; i++) {
 527                 struct drm_connector_state *conn_state;
 528
 529                 conn_state = state->connector_states[i];
 530
 531                 if (conn_state && conn_state->crtc == crtc)
 532                         num_connected_connectors++;
 533         }
 534
 535         DRM_DEBUG_KMS("State %p has %i connectors for [CRTC:%d]\n",
 536                       state, num_connected_connectors, crtc->base.id);
 537
 538         return num_connected_connectors;
 539 }
 540 EXPORT_SYMBOL(drm_atomic_connectors_for_crtc);
 541
 542 /**
 543  * drm_atomic_legacy_backoff - locking backoff for legacy ioctls
 544  * @state: atomic state
 545  *
 546  * This function should be used by legacy entry points which don't understand
 547  * -EDEADLK semantics. For simplicity this one will grab all modeset locks after
 548  *  the slowpath completed.
 549  */
 550 void drm_atomic_legacy_backoff(struct drm_atomic_state *state)
 551 {
 552         int ret;
 553
 554 retry:
 555         drm_modeset_backoff(state->acquire_ctx);
 556
 557         ret = drm_modeset_lock(&state->dev->mode_config.connection_mutex,
 558                                state->acquire_ctx);
 559         if (ret)
 560                 goto retry;
 561         ret = drm_modeset_lock_all_crtcs(state->dev,
 562                                          state->acquire_ctx);
 563         if (ret)
 564                 goto retry;
 565 }
 566 EXPORT_SYMBOL(drm_atomic_legacy_backoff);
 567
 568 /**
 569  * drm_atomic_check_only - check whether a given config would work
 570  * @state: atomic configuration to check
 571  *
 572  * Note that this function can return -EDEADLK if the driver needed to acquire
 573  * more locks but encountered a deadlock. The caller must then do the usual w/w
 574  * backoff dance and restart. All other errors are fatal.
 575  *
 576  * Returns:
 577  * 0 on success, negative error code on failure.
 578  */
 579 int drm_atomic_check_only(struct drm_atomic_state *state)
 580 {
 581         struct drm_mode_config *config = &state->dev->mode_config;
 582
 583         DRM_DEBUG_KMS("checking %p\n", state);
 584
 585         if (config->funcs->atomic_check)
 586                 return config->funcs->atomic_check(state->dev, state);
 587         else
 588                 return 0;
 589 }
 590 EXPORT_SYMBOL(drm_atomic_check_only);
 591
 592 /**
 593  * drm_atomic_commit - commit configuration atomically
 594  * @state: atomic configuration to check
 595  *
 596  * Note that this function can return -EDEADLK if the driver needed to acquire
 597  * more locks but encountered a deadlock. The caller must then do the usual w/w
 598  * backoff dance and restart. All other errors are fatal.
 599  *
 600  * Also note that on successful execution ownership of @state is transferred
 601  * from the caller of this function to the function itself. The caller must not
 602  * free or in any other way access @state. If the function fails then the caller
 603  * must clean up @state itself.
 604  *
 605  * Returns:
 606  * 0 on success, negative error code on failure.
 607  */
 608 int drm_atomic_commit(struct drm_atomic_state *state)
 609 {
 610         struct drm_mode_config *config = &state->dev->mode_config;
 611         int ret;
 612
 613         ret = drm_atomic_check_only(state);
 614         if (ret)
 615                 return ret;
 616
 617         DRM_DEBUG_KMS("commiting %p\n", state);
 618
 619         return config->funcs->atomic_commit(state->dev, state, false);
 620 }
 621 EXPORT_SYMBOL(drm_atomic_commit);
 622
 623 /**
 624  * drm_atomic_async_commit - atomic&async configuration commit
 625  * @state: atomic configuration to check
 626  *
 627  * Note that this function can return -EDEADLK if the driver needed to acquire
 628  * more locks but encountered a deadlock. The caller must then do the usual w/w
 629  * backoff dance and restart. All other errors are fatal.
 630  *
 631  * Also note that on successful execution ownership of @state is transferred
 632  * from the caller of this function to the function itself. The caller must not
 633  * free or in any other way access @state. If the function fails then the caller
 634  * must clean up @state itself.
 635  *
 636  * Returns:
 637  * 0 on success, negative error code on failure.
 638  */
 639 int drm_atomic_async_commit(struct drm_atomic_state *state)
 640 {
 641         struct drm_mode_config *config = &state->dev->mode_config;
 642         int ret;
 643
 644         ret = drm_atomic_check_only(state);
 645         if (ret)
 646                 return ret;
 647
 648         DRM_DEBUG_KMS("commiting %p asynchronously\n", state);
 649
 650         return config->funcs->atomic_commit(state->dev, state, true);
 651 }
 652 EXPORT_SYMBOL(drm_atomic_async_commit);