git.oblomov.eu Git - linux-2.6/blob - drivers/gpu/drm/drm_irq.c

   1 /**
   2  * \file drm_irq.c
   3  * IRQ support
   4  *
   5  * \author Rickard E. (Rik) Faith <faith@valinux.com>
   6  * \author Gareth Hughes <gareth@valinux.com>
   7  */
   8
   9 /*
  10  * Created: Fri Mar 19 14:30:16 1999 by faith@valinux.com
  11  *
  12  * Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
  13  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
  14  * All Rights Reserved.
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a
  17  * copy of this software and associated documentation files (the "Software"),
  18  * to deal in the Software without restriction, including without limitation
  19  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  20  * and/or sell copies of the Software, and to permit persons to whom the
  21  * Software is furnished to do so, subject to the following conditions:
  22  *
  23  * The above copyright notice and this permission notice (including the next
  24  * paragraph) shall be included in all copies or substantial portions of the
  25  * Software.
  26  *
  27  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  28  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  29  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  30  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  31  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  32  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  33  * OTHER DEALINGS IN THE SOFTWARE.
  34  */
  35
  36 #include "drmP.h"
  37
  38 #include <linux/interrupt.h>    /* For task queue support */
  39
  40 /**
  41  * Get interrupt from bus id.
  42  *
  43  * \param inode device inode.
  44  * \param file_priv DRM file private.
  45  * \param cmd command.
  46  * \param arg user argument, pointing to a drm_irq_busid structure.
  47  * \return zero on success or a negative number on failure.
  48  *
  49  * Finds the PCI device with the specified bus id and gets its IRQ number.
  50  * This IOCTL is deprecated, and will now return EINVAL for any busid not equal
  51  * to that of the device that this DRM instance attached to.
  52  */
  53 int drm_irq_by_busid(struct drm_device *dev, void *data,
  54                      struct drm_file *file_priv)
  55 {
  56         struct drm_irq_busid *p = data;
  57
  58         if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
  59                 return -EINVAL;
  60
  61         if ((p->busnum >> 8) != drm_get_pci_domain(dev) ||
  62             (p->busnum & 0xff) != dev->pdev->bus->number ||
  63             p->devnum != PCI_SLOT(dev->pdev->devfn) || p->funcnum != PCI_FUNC(dev->pdev->devfn))
  64                 return -EINVAL;
  65
  66         p->irq = dev->pdev->irq;
  67
  68         DRM_DEBUG("%d:%d:%d => IRQ %d\n", p->busnum, p->devnum, p->funcnum,
  69                   p->irq);
  70
  71         return 0;
  72 }
  73
  74 static void vblank_disable_fn(unsigned long arg)
  75 {
  76         struct drm_device *dev = (struct drm_device *)arg;
  77         unsigned long irqflags;
  78         int i;
  79
  80         if (!dev->vblank_disable_allowed)
  81                 return;
  82
  83         for (i = 0; i < dev->num_crtcs; i++) {
  84                 spin_lock_irqsave(&dev->vbl_lock, irqflags);
  85                 if (atomic_read(&dev->vblank_refcount[i]) == 0 &&
  86                     dev->vblank_enabled[i]) {
  87                         DRM_DEBUG("disabling vblank on crtc %d\n", i);
  88                         dev->last_vblank[i] =
  89                                 dev->driver->get_vblank_counter(dev, i);
  90                         dev->driver->disable_vblank(dev, i);
  91                         dev->vblank_enabled[i] = 0;
  92                 }
  93                 spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
  94         }
  95 }
  96
  97 void drm_vblank_cleanup(struct drm_device *dev)
  98 {
  99         /* Bail if the driver didn't call drm_vblank_init() */
 100         if (dev->num_crtcs == 0)
 101                 return;
 102
 103         del_timer(&dev->vblank_disable_timer);
 104
 105         vblank_disable_fn((unsigned long)dev);
 106
 107         drm_free(dev->vbl_queue, sizeof(*dev->vbl_queue) * dev->num_crtcs,
 108                  DRM_MEM_DRIVER);
 109         drm_free(dev->vbl_sigs, sizeof(*dev->vbl_sigs) * dev->num_crtcs,
 110                  DRM_MEM_DRIVER);
 111         drm_free(dev->_vblank_count, sizeof(*dev->_vblank_count) *
 112                  dev->num_crtcs, DRM_MEM_DRIVER);
 113         drm_free(dev->vblank_refcount, sizeof(*dev->vblank_refcount) *
 114                  dev->num_crtcs, DRM_MEM_DRIVER);
 115         drm_free(dev->vblank_enabled, sizeof(*dev->vblank_enabled) *
 116                  dev->num_crtcs, DRM_MEM_DRIVER);
 117         drm_free(dev->last_vblank, sizeof(*dev->last_vblank) * dev->num_crtcs,
 118                  DRM_MEM_DRIVER);
 119         drm_free(dev->last_vblank_wait,
 120                  sizeof(*dev->last_vblank_wait) * dev->num_crtcs,
 121                  DRM_MEM_DRIVER);
 122         drm_free(dev->vblank_inmodeset, sizeof(*dev->vblank_inmodeset) *
 123                  dev->num_crtcs, DRM_MEM_DRIVER);
 124
 125         dev->num_crtcs = 0;
 126 }
 127
 128 int drm_vblank_init(struct drm_device *dev, int num_crtcs)
 129 {
 130         int i, ret = -ENOMEM;
 131
 132         setup_timer(&dev->vblank_disable_timer, vblank_disable_fn,
 133                     (unsigned long)dev);
 134         spin_lock_init(&dev->vbl_lock);
 135         atomic_set(&dev->vbl_signal_pending, 0);
 136         dev->num_crtcs = num_crtcs;
 137
 138         dev->vbl_queue = drm_alloc(sizeof(wait_queue_head_t) * num_crtcs,
 139                                    DRM_MEM_DRIVER);
 140         if (!dev->vbl_queue)
 141                 goto err;
 142
 143         dev->vbl_sigs = drm_alloc(sizeof(struct list_head) * num_crtcs,
 144                                   DRM_MEM_DRIVER);
 145         if (!dev->vbl_sigs)
 146                 goto err;
 147
 148         dev->_vblank_count = drm_alloc(sizeof(atomic_t) * num_crtcs,
 149                                       DRM_MEM_DRIVER);
 150         if (!dev->_vblank_count)
 151                 goto err;
 152
 153         dev->vblank_refcount = drm_alloc(sizeof(atomic_t) * num_crtcs,
 154                                          DRM_MEM_DRIVER);
 155         if (!dev->vblank_refcount)
 156                 goto err;
 157
 158         dev->vblank_enabled = drm_calloc(num_crtcs, sizeof(int),
 159                                          DRM_MEM_DRIVER);
 160         if (!dev->vblank_enabled)
 161                 goto err;
 162
 163         dev->last_vblank = drm_calloc(num_crtcs, sizeof(u32), DRM_MEM_DRIVER);
 164         if (!dev->last_vblank)
 165                 goto err;
 166
 167         dev->last_vblank_wait = drm_calloc(num_crtcs, sizeof(u32),
 168                                            DRM_MEM_DRIVER);
 169         if (!dev->last_vblank_wait)
 170                 goto err;
 171
 172         dev->vblank_inmodeset = drm_calloc(num_crtcs, sizeof(int),
 173                                          DRM_MEM_DRIVER);
 174         if (!dev->vblank_inmodeset)
 175                 goto err;
 176
 177         /* Zero per-crtc vblank stuff */
 178         for (i = 0; i < num_crtcs; i++) {
 179                 init_waitqueue_head(&dev->vbl_queue[i]);
 180                 INIT_LIST_HEAD(&dev->vbl_sigs[i]);
 181                 atomic_set(&dev->_vblank_count[i], 0);
 182                 atomic_set(&dev->vblank_refcount[i], 0);
 183         }
 184
 185         dev->vblank_disable_allowed = 0;
 186
 187         return 0;
 188
 189 err:
 190         drm_vblank_cleanup(dev);
 191         return ret;
 192 }
 193 EXPORT_SYMBOL(drm_vblank_init);
 194
 195 /**
 196  * Install IRQ handler.
 197  *
 198  * \param dev DRM device.
 199  *
 200  * Initializes the IRQ related data. Installs the handler, calling the driver
 201  * \c drm_driver_irq_preinstall() and \c drm_driver_irq_postinstall() functions
 202  * before and after the installation.
 203  */
 204 int drm_irq_install(struct drm_device *dev)
 205 {
 206         int ret = 0;
 207         unsigned long sh_flags = 0;
 208
 209         if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 210                 return -EINVAL;
 211
 212         if (dev->pdev->irq == 0)
 213                 return -EINVAL;
 214
 215         mutex_lock(&dev->struct_mutex);
 216
 217         /* Driver must have been initialized */
 218         if (!dev->dev_private) {
 219                 mutex_unlock(&dev->struct_mutex);
 220                 return -EINVAL;
 221         }
 222
 223         if (dev->irq_enabled) {
 224                 mutex_unlock(&dev->struct_mutex);
 225                 return -EBUSY;
 226         }
 227         dev->irq_enabled = 1;
 228         mutex_unlock(&dev->struct_mutex);
 229
 230         DRM_DEBUG("irq=%d\n", dev->pdev->irq);
 231
 232         /* Before installing handler */
 233         dev->driver->irq_preinstall(dev);
 234
 235         /* Install handler */
 236         if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
 237                 sh_flags = IRQF_SHARED;
 238
 239         ret = request_irq(drm_dev_to_irq(dev), dev->driver->irq_handler,
 240                           sh_flags, dev->devname, dev);
 241
 242         if (ret < 0) {
 243                 mutex_lock(&dev->struct_mutex);
 244                 dev->irq_enabled = 0;
 245                 mutex_unlock(&dev->struct_mutex);
 246                 return ret;
 247         }
 248
 249         /* After installing handler */
 250         ret = dev->driver->irq_postinstall(dev);
 251         if (ret < 0) {
 252                 mutex_lock(&dev->struct_mutex);
 253                 dev->irq_enabled = 0;
 254                 mutex_unlock(&dev->struct_mutex);
 255         }
 256
 257         return ret;
 258 }
 259 EXPORT_SYMBOL(drm_irq_install);
 260
 261 /**
 262  * Uninstall the IRQ handler.
 263  *
 264  * \param dev DRM device.
 265  *
 266  * Calls the driver's \c drm_driver_irq_uninstall() function, and stops the irq.
 267  */
 268 int drm_irq_uninstall(struct drm_device * dev)
 269 {
 270         unsigned long irqflags;
 271         int irq_enabled, i;
 272
 273         if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 274                 return -EINVAL;
 275
 276         mutex_lock(&dev->struct_mutex);
 277         irq_enabled = dev->irq_enabled;
 278         dev->irq_enabled = 0;
 279         mutex_unlock(&dev->struct_mutex);
 280
 281         /*
 282          * Wake up any waiters so they don't hang.
 283          */
 284         spin_lock_irqsave(&dev->vbl_lock, irqflags);
 285         for (i = 0; i < dev->num_crtcs; i++) {
 286                 DRM_WAKEUP(&dev->vbl_queue[i]);
 287                 dev->vblank_enabled[i] = 0;
 288         }
 289         spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 290
 291         if (!irq_enabled)
 292                 return -EINVAL;
 293
 294         DRM_DEBUG("irq=%d\n", dev->pdev->irq);
 295
 296         dev->driver->irq_uninstall(dev);
 297
 298         free_irq(dev->pdev->irq, dev);
 299
 300         return 0;
 301 }
 302 EXPORT_SYMBOL(drm_irq_uninstall);
 303
 304 /**
 305  * IRQ control ioctl.
 306  *
 307  * \param inode device inode.
 308  * \param file_priv DRM file private.
 309  * \param cmd command.
 310  * \param arg user argument, pointing to a drm_control structure.
 311  * \return zero on success or a negative number on failure.
 312  *
 313  * Calls irq_install() or irq_uninstall() according to \p arg.
 314  */
 315 int drm_control(struct drm_device *dev, void *data,
 316                 struct drm_file *file_priv)
 317 {
 318         struct drm_control *ctl = data;
 319
 320         /* if we haven't irq we fallback for compatibility reasons - this used to be a separate function in drm_dma.h */
 321
 322
 323         switch (ctl->func) {
 324         case DRM_INST_HANDLER:
 325                 if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 326                         return 0;
 327                 if (drm_core_check_feature(dev, DRIVER_MODESET))
 328                         return 0;
 329                 if (dev->if_version < DRM_IF_VERSION(1, 2) &&
 330                     ctl->irq != dev->pdev->irq)
 331                         return -EINVAL;
 332                 return drm_irq_install(dev);
 333         case DRM_UNINST_HANDLER:
 334                 if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 335                         return 0;
 336                 if (drm_core_check_feature(dev, DRIVER_MODESET))
 337                         return 0;
 338                 return drm_irq_uninstall(dev);
 339         default:
 340                 return -EINVAL;
 341         }
 342 }
 343
 344 /**
 345  * drm_vblank_count - retrieve "cooked" vblank counter value
 346  * @dev: DRM device
 347  * @crtc: which counter to retrieve
 348  *
 349  * Fetches the "cooked" vblank count value that represents the number of
 350  * vblank events since the system was booted, including lost events due to
 351  * modesetting activity.
 352  */
 353 u32 drm_vblank_count(struct drm_device *dev, int crtc)
 354 {
 355         return atomic_read(&dev->_vblank_count[crtc]);
 356 }
 357 EXPORT_SYMBOL(drm_vblank_count);
 358
 359 /**
 360  * drm_update_vblank_count - update the master vblank counter
 361  * @dev: DRM device
 362  * @crtc: counter to update
 363  *
 364  * Call back into the driver to update the appropriate vblank counter
 365  * (specified by @crtc).  Deal with wraparound, if it occurred, and
 366  * update the last read value so we can deal with wraparound on the next
 367  * call if necessary.
 368  *
 369  * Only necessary when going from off->on, to account for frames we
 370  * didn't get an interrupt for.
 371  *
 372  * Note: caller must hold dev->vbl_lock since this reads & writes
 373  * device vblank fields.
 374  */
 375 static void drm_update_vblank_count(struct drm_device *dev, int crtc)
 376 {
 377         u32 cur_vblank, diff;
 378
 379         /*
 380          * Interrupts were disabled prior to this call, so deal with counter
 381          * wrap if needed.
 382          * NOTE!  It's possible we lost a full dev->max_vblank_count events
 383          * here if the register is small or we had vblank interrupts off for
 384          * a long time.
 385          */
 386         cur_vblank = dev->driver->get_vblank_counter(dev, crtc);
 387         diff = cur_vblank - dev->last_vblank[crtc];
 388         if (cur_vblank < dev->last_vblank[crtc]) {
 389                 diff += dev->max_vblank_count;
 390
 391                 DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
 392                           crtc, dev->last_vblank[crtc], cur_vblank, diff);
 393         }
 394
 395         DRM_DEBUG("enabling vblank interrupts on crtc %d, missed %d\n",
 396                   crtc, diff);
 397
 398         atomic_add(diff, &dev->_vblank_count[crtc]);
 399 }
 400
 401 /**
 402  * drm_vblank_get - get a reference count on vblank events
 403  * @dev: DRM device
 404  * @crtc: which CRTC to own
 405  *
 406  * Acquire a reference count on vblank events to avoid having them disabled
 407  * while in use.
 408  *
 409  * RETURNS
 410  * Zero on success, nonzero on failure.
 411  */
 412 int drm_vblank_get(struct drm_device *dev, int crtc)
 413 {
 414         unsigned long irqflags;
 415         int ret = 0;
 416
 417         spin_lock_irqsave(&dev->vbl_lock, irqflags);
 418         /* Going from 0->1 means we have to enable interrupts again */
 419         if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1 &&
 420             !dev->vblank_enabled[crtc]) {
 421                 ret = dev->driver->enable_vblank(dev, crtc);
 422                 DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n", crtc, ret);
 423                 if (ret)
 424                         atomic_dec(&dev->vblank_refcount[crtc]);
 425                 else {
 426                         dev->vblank_enabled[crtc] = 1;
 427                         drm_update_vblank_count(dev, crtc);
 428                 }
 429         }
 430         spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 431
 432         return ret;
 433 }
 434 EXPORT_SYMBOL(drm_vblank_get);
 435
 436 /**
 437  * drm_vblank_put - give up ownership of vblank events
 438  * @dev: DRM device
 439  * @crtc: which counter to give up
 440  *
 441  * Release ownership of a given vblank counter, turning off interrupts
 442  * if possible.
 443  */
 444 void drm_vblank_put(struct drm_device *dev, int crtc)
 445 {
 446         /* Last user schedules interrupt disable */
 447         if (atomic_dec_and_test(&dev->vblank_refcount[crtc]))
 448                 mod_timer(&dev->vblank_disable_timer, jiffies + 5*DRM_HZ);
 449 }
 450 EXPORT_SYMBOL(drm_vblank_put);
 451
 452 /**
 453  * drm_vblank_pre_modeset - account for vblanks across mode sets
 454  * @dev: DRM device
 455  * @crtc: CRTC in question
 456  * @post: post or pre mode set?
 457  *
 458  * Account for vblank events across mode setting events, which will likely
 459  * reset the hardware frame counter.
 460  */
 461 void drm_vblank_pre_modeset(struct drm_device *dev, int crtc)
 462 {
 463         /*
 464          * To avoid all the problems that might happen if interrupts
 465          * were enabled/disabled around or between these calls, we just
 466          * have the kernel take a reference on the CRTC (just once though
 467          * to avoid corrupting the count if multiple, mismatch calls occur),
 468          * so that interrupts remain enabled in the interim.
 469          */
 470         if (!dev->vblank_inmodeset[crtc]) {
 471                 dev->vblank_inmodeset[crtc] = 1;
 472                 drm_vblank_get(dev, crtc);
 473         }
 474 }
 475 EXPORT_SYMBOL(drm_vblank_pre_modeset);
 476
 477 void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
 478 {
 479         unsigned long irqflags;
 480
 481         if (dev->vblank_inmodeset[crtc]) {
 482                 spin_lock_irqsave(&dev->vbl_lock, irqflags);
 483                 dev->vblank_disable_allowed = 1;
 484                 dev->vblank_inmodeset[crtc] = 0;
 485                 spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 486                 drm_vblank_put(dev, crtc);
 487         }
 488 }
 489 EXPORT_SYMBOL(drm_vblank_post_modeset);
 490
 491 /**
 492  * drm_modeset_ctl - handle vblank event counter changes across mode switch
 493  * @DRM_IOCTL_ARGS: standard ioctl arguments
 494  *
 495  * Applications should call the %_DRM_PRE_MODESET and %_DRM_POST_MODESET
 496  * ioctls around modesetting so that any lost vblank events are accounted for.
 497  *
 498  * Generally the counter will reset across mode sets.  If interrupts are
 499  * enabled around this call, we don't have to do anything since the counter
 500  * will have already been incremented.
 501  */
 502 int drm_modeset_ctl(struct drm_device *dev, void *data,
 503                     struct drm_file *file_priv)
 504 {
 505         struct drm_modeset_ctl *modeset = data;
 506         int crtc, ret = 0;
 507
 508         /* If drm_vblank_init() hasn't been called yet, just no-op */
 509         if (!dev->num_crtcs)
 510                 goto out;
 511
 512         crtc = modeset->crtc;
 513         if (crtc >= dev->num_crtcs) {
 514                 ret = -EINVAL;
 515                 goto out;
 516         }
 517
 518         switch (modeset->cmd) {
 519         case _DRM_PRE_MODESET:
 520                 drm_vblank_pre_modeset(dev, crtc);
 521                 break;
 522         case _DRM_POST_MODESET:
 523                 drm_vblank_post_modeset(dev, crtc);
 524                 break;
 525         default:
 526                 ret = -EINVAL;
 527                 break;
 528         }
 529
 530 out:
 531         return ret;
 532 }
 533
 534 /**
 535  * Wait for VBLANK.
 536  *
 537  * \param inode device inode.
 538  * \param file_priv DRM file private.
 539  * \param cmd command.
 540  * \param data user argument, pointing to a drm_wait_vblank structure.
 541  * \return zero on success or a negative number on failure.
 542  *
 543  * Verifies the IRQ is installed.
 544  *
 545  * If a signal is requested checks if this task has already scheduled the same signal
 546  * for the same vblank sequence number - nothing to be done in
 547  * that case. If the number of tasks waiting for the interrupt exceeds 100 the
 548  * function fails. Otherwise adds a new entry to drm_device::vbl_sigs for this
 549  * task.
 550  *
 551  * If a signal is not requested, then calls vblank_wait().
 552  */
 553 int drm_wait_vblank(struct drm_device *dev, void *data,
 554                     struct drm_file *file_priv)
 555 {
 556         union drm_wait_vblank *vblwait = data;
 557         int ret = 0;
 558         unsigned int flags, seq, crtc;
 559
 560         if ((!dev->pdev->irq) || (!dev->irq_enabled))
 561                 return -EINVAL;
 562
 563         if (vblwait->request.type &
 564             ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK)) {
 565                 DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
 566                           vblwait->request.type,
 567                           (_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK));
 568                 return -EINVAL;
 569         }
 570
 571         flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
 572         crtc = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;
 573
 574         if (crtc >= dev->num_crtcs)
 575                 return -EINVAL;
 576
 577         ret = drm_vblank_get(dev, crtc);
 578         if (ret) {
 579                 DRM_ERROR("failed to acquire vblank counter, %d\n", ret);
 580                 return ret;
 581         }
 582         seq = drm_vblank_count(dev, crtc);
 583
 584         switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
 585         case _DRM_VBLANK_RELATIVE:
 586                 vblwait->request.sequence += seq;
 587                 vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
 588         case _DRM_VBLANK_ABSOLUTE:
 589                 break;
 590         default:
 591                 ret = -EINVAL;
 592                 goto done;
 593         }
 594
 595         if ((flags & _DRM_VBLANK_NEXTONMISS) &&
 596             (seq - vblwait->request.sequence) <= (1<<23)) {
 597                 vblwait->request.sequence = seq + 1;
 598         }
 599
 600         if (flags & _DRM_VBLANK_SIGNAL) {
 601                 unsigned long irqflags;
 602                 struct list_head *vbl_sigs = &dev->vbl_sigs[crtc];
 603                 struct drm_vbl_sig *vbl_sig;
 604
 605                 spin_lock_irqsave(&dev->vbl_lock, irqflags);
 606
 607                 /* Check if this task has already scheduled the same signal
 608                  * for the same vblank sequence number; nothing to be done in
 609                  * that case
 610                  */
 611                 list_for_each_entry(vbl_sig, vbl_sigs, head) {
 612                         if (vbl_sig->sequence == vblwait->request.sequence
 613                             && vbl_sig->info.si_signo ==
 614                             vblwait->request.signal
 615                             && vbl_sig->task == current) {
 616                                 spin_unlock_irqrestore(&dev->vbl_lock,
 617                                                        irqflags);
 618                                 vblwait->reply.sequence = seq;
 619                                 goto done;
 620                         }
 621                 }
 622
 623                 if (atomic_read(&dev->vbl_signal_pending) >= 100) {
 624                         spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 625                         ret = -EBUSY;
 626                         goto done;
 627                 }
 628
 629                 spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 630
 631                 vbl_sig = drm_calloc(1, sizeof(struct drm_vbl_sig),
 632                                      DRM_MEM_DRIVER);
 633                 if (!vbl_sig) {
 634                         ret = -ENOMEM;
 635                         goto done;
 636                 }
 637
 638                 /* Get a refcount on the vblank, which will be released by
 639                  * drm_vbl_send_signals().
 640                  */
 641                 ret = drm_vblank_get(dev, crtc);
 642                 if (ret) {
 643                         drm_free(vbl_sig, sizeof(struct drm_vbl_sig),
 644                                  DRM_MEM_DRIVER);
 645                         goto done;
 646                 }
 647
 648                 atomic_inc(&dev->vbl_signal_pending);
 649
 650                 vbl_sig->sequence = vblwait->request.sequence;
 651                 vbl_sig->info.si_signo = vblwait->request.signal;
 652                 vbl_sig->task = current;
 653
 654                 spin_lock_irqsave(&dev->vbl_lock, irqflags);
 655
 656                 list_add_tail(&vbl_sig->head, vbl_sigs);
 657
 658                 spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 659
 660                 vblwait->reply.sequence = seq;
 661         } else {
 662                 DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
 663                           vblwait->request.sequence, crtc);
 664                 dev->last_vblank_wait[crtc] = vblwait->request.sequence;
 665                 DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
 666                             (((drm_vblank_count(dev, crtc) -
 667                                vblwait->request.sequence) <= (1 << 23)) ||
 668                              !dev->irq_enabled));
 669
 670                 if (ret != -EINTR) {
 671                         struct timeval now;
 672
 673                         do_gettimeofday(&now);
 674
 675                         vblwait->reply.tval_sec = now.tv_sec;
 676                         vblwait->reply.tval_usec = now.tv_usec;
 677                         vblwait->reply.sequence = drm_vblank_count(dev, crtc);
 678                         DRM_DEBUG("returning %d to client\n",
 679                                   vblwait->reply.sequence);
 680                 } else {
 681                         DRM_DEBUG("vblank wait interrupted by signal\n");
 682                 }
 683         }
 684
 685 done:
 686         drm_vblank_put(dev, crtc);
 687         return ret;
 688 }
 689
 690 /**
 691  * Send the VBLANK signals.
 692  *
 693  * \param dev DRM device.
 694  * \param crtc CRTC where the vblank event occurred
 695  *
 696  * Sends a signal for each task in drm_device::vbl_sigs and empties the list.
 697  *
 698  * If a signal is not requested, then calls vblank_wait().
 699  */
 700 static void drm_vbl_send_signals(struct drm_device *dev, int crtc)
 701 {
 702         struct drm_vbl_sig *vbl_sig, *tmp;
 703         struct list_head *vbl_sigs;
 704         unsigned int vbl_seq;
 705         unsigned long flags;
 706
 707         spin_lock_irqsave(&dev->vbl_lock, flags);
 708
 709         vbl_sigs = &dev->vbl_sigs[crtc];
 710         vbl_seq = drm_vblank_count(dev, crtc);
 711
 712         list_for_each_entry_safe(vbl_sig, tmp, vbl_sigs, head) {
 713             if ((vbl_seq - vbl_sig->sequence) <= (1 << 23)) {
 714                 vbl_sig->info.si_code = vbl_seq;
 715                 send_sig_info(vbl_sig->info.si_signo,
 716                               &vbl_sig->info, vbl_sig->task);
 717
 718                 list_del(&vbl_sig->head);
 719
 720                 drm_free(vbl_sig, sizeof(*vbl_sig),
 721                          DRM_MEM_DRIVER);
 722                 atomic_dec(&dev->vbl_signal_pending);
 723                 drm_vblank_put(dev, crtc);
 724             }
 725         }
 726
 727         spin_unlock_irqrestore(&dev->vbl_lock, flags);
 728 }
 729
 730 /**
 731  * drm_handle_vblank - handle a vblank event
 732  * @dev: DRM device
 733  * @crtc: where this event occurred
 734  *
 735  * Drivers should call this routine in their vblank interrupt handlers to
 736  * update the vblank counter and send any signals that may be pending.
 737  */
 738 void drm_handle_vblank(struct drm_device *dev, int crtc)
 739 {
 740         atomic_inc(&dev->_vblank_count[crtc]);
 741         DRM_WAKEUP(&dev->vbl_queue[crtc]);
 742         drm_vbl_send_signals(dev, crtc);
 743 }
 744 EXPORT_SYMBOL(drm_handle_vblank);