drivers/gpu/drm/drm_irq.c - linux - Git at Google

 /**
  * \file drm_irq.c
  * IRQ support
  *
  * \author Rickard E. (Rik) Faith <faith@valinux.com>
  * \author Gareth Hughes <gareth@valinux.com>
  */

 /*
  * Created: Fri Mar 19 14:30:16 1999 by faith@valinux.com
  *
  * Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the next
  * paragraph) shall be included in all copies or substantial portions of the
  * Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  */

 #include "drmP.h"

 #include <linux/interrupt.h>	/* For task queue support */

 #include <linux/vgaarb.h>
 /**
  * Get interrupt from bus id.
  *
  * \param inode device inode.
  * \param file_priv DRM file private.
  * \param cmd command.
  * \param arg user argument, pointing to a drm_irq_busid structure.
  * \return zero on success or a negative number on failure.
  *
  * Finds the PCI device with the specified bus id and gets its IRQ number.
  * This IOCTL is deprecated, and will now return EINVAL for any busid not equal
  * to that of the device that this DRM instance attached to.
  */
 int drm_irq_by_busid(struct drm_device *dev, void *data,
 		     struct drm_file *file_priv)
 {
 	struct drm_irq_busid *p = data;

 	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 		return -EINVAL;

 	if ((p->busnum >> 8) != drm_get_pci_domain(dev) ||
 	    (p->busnum & 0xff) != dev->pdev->bus->number ||
 	    p->devnum != PCI_SLOT(dev->pdev->devfn) || p->funcnum != PCI_FUNC(dev->pdev->devfn))
 		return -EINVAL;

 	p->irq = dev->pdev->irq;

 	DRM_DEBUG("%d:%d:%d => IRQ %d\n", p->busnum, p->devnum, p->funcnum,
 		  p->irq);

 	return 0;
 }

 static void vblank_disable_fn(unsigned long arg)
 {
 	struct drm_device *dev = (struct drm_device *)arg;
 	unsigned long irqflags;
 	int i;

 	if (!dev->vblank_disable_allowed)
 		return;

 	for (i = 0; i < dev->num_crtcs; i++) {
 		spin_lock_irqsave(&dev->vbl_lock, irqflags);
 		if (atomic_read(&dev->vblank_refcount[i]) == 0 &&
 		    dev->vblank_enabled[i]) {
 			DRM_DEBUG("disabling vblank on crtc %d\n", i);
 			dev->last_vblank[i] =
 				dev->driver->get_vblank_counter(dev, i);
 			dev->driver->disable_vblank(dev, i);
 			dev->vblank_enabled[i] = 0;
 		}
 		spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 	}
 }

 void drm_vblank_cleanup(struct drm_device *dev)
 {
 	/* Bail if the driver didn't call drm_vblank_init() */
 	if (dev->num_crtcs == 0)
 		return;

 	del_timer(&dev->vblank_disable_timer);

 	vblank_disable_fn((unsigned long)dev);

 	kfree(dev->vbl_queue);
 	kfree(dev->_vblank_count);
 	kfree(dev->vblank_refcount);
 	kfree(dev->vblank_enabled);
 	kfree(dev->last_vblank);
 	kfree(dev->last_vblank_wait);
 	kfree(dev->vblank_inmodeset);

 	dev->num_crtcs = 0;
 }

 int drm_vblank_init(struct drm_device *dev, int num_crtcs)
 {
 	int i, ret = -ENOMEM;

 	setup_timer(&dev->vblank_disable_timer, vblank_disable_fn,
 		    (unsigned long)dev);
 	spin_lock_init(&dev->vbl_lock);
 	dev->num_crtcs = num_crtcs;

 	dev->vbl_queue = kmalloc(sizeof(wait_queue_head_t) * num_crtcs,
 				 GFP_KERNEL);
 	if (!dev->vbl_queue)
 		goto err;

 	dev->_vblank_count = kmalloc(sizeof(atomic_t) * num_crtcs, GFP_KERNEL);
 	if (!dev->_vblank_count)
 		goto err;

 	dev->vblank_refcount = kmalloc(sizeof(atomic_t) * num_crtcs,
 				       GFP_KERNEL);
 	if (!dev->vblank_refcount)
 		goto err;

 	dev->vblank_enabled = kcalloc(num_crtcs, sizeof(int), GFP_KERNEL);
 	if (!dev->vblank_enabled)
 		goto err;

 	dev->last_vblank = kcalloc(num_crtcs, sizeof(u32), GFP_KERNEL);
 	if (!dev->last_vblank)
 		goto err;

 	dev->last_vblank_wait = kcalloc(num_crtcs, sizeof(u32), GFP_KERNEL);
 	if (!dev->last_vblank_wait)
 		goto err;

 	dev->vblank_inmodeset = kcalloc(num_crtcs, sizeof(int), GFP_KERNEL);
 	if (!dev->vblank_inmodeset)
 		goto err;

 	/* Zero per-crtc vblank stuff */
 	for (i = 0; i < num_crtcs; i++) {
 		init_waitqueue_head(&dev->vbl_queue[i]);
 		atomic_set(&dev->_vblank_count[i], 0);
 		atomic_set(&dev->vblank_refcount[i], 0);
 	}

 	dev->vblank_disable_allowed = 0;

 	return 0;

 err:
 	drm_vblank_cleanup(dev);
 	return ret;
 }
 EXPORT_SYMBOL(drm_vblank_init);

 static void drm_irq_vgaarb_nokms(void *cookie, bool state)
 {
 	struct drm_device *dev = cookie;

 	if (dev->driver->vgaarb_irq) {
 		dev->driver->vgaarb_irq(dev, state);
 		return;
 	}

 	if (!dev->irq_enabled)
 		return;

 	if (state)
 		dev->driver->irq_uninstall(dev);
 	else {
 		dev->driver->irq_preinstall(dev);
 		dev->driver->irq_postinstall(dev);
 	}
 }

 /**
  * Install IRQ handler.
  *
  * \param dev DRM device.
  *
  * Initializes the IRQ related data. Installs the handler, calling the driver
  * \c drm_driver_irq_preinstall() and \c drm_driver_irq_postinstall() functions
  * before and after the installation.
  */
 int drm_irq_install(struct drm_device *dev)
 {
 	int ret = 0;
 	unsigned long sh_flags = 0;
 	char *irqname;

 	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 		return -EINVAL;

 	if (dev->pdev->irq == 0)
 		return -EINVAL;

 	mutex_lock(&dev->struct_mutex);

 	/* Driver must have been initialized */
 	if (!dev->dev_private) {
 		mutex_unlock(&dev->struct_mutex);
 		return -EINVAL;
 	}

 	if (dev->irq_enabled) {
 		mutex_unlock(&dev->struct_mutex);
 		return -EBUSY;
 	}
 	dev->irq_enabled = 1;
 	mutex_unlock(&dev->struct_mutex);

 	DRM_DEBUG("irq=%d\n", dev->pdev->irq);

 	/* Before installing handler */
 	dev->driver->irq_preinstall(dev);

 	/* Install handler */
 	if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
 		sh_flags = IRQF_SHARED;

 	if (dev->devname)
 		irqname = dev->devname;
 	else
 		irqname = dev->driver->name;

 	ret = request_irq(drm_dev_to_irq(dev), dev->driver->irq_handler,
 			  sh_flags, irqname, dev);

 	if (ret < 0) {
 		mutex_lock(&dev->struct_mutex);
 		dev->irq_enabled = 0;
 		mutex_unlock(&dev->struct_mutex);
 		return ret;
 	}

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		vga_client_register(dev->pdev, (void *)dev, drm_irq_vgaarb_nokms, NULL);

 	/* After installing handler */
 	ret = dev->driver->irq_postinstall(dev);
 	if (ret < 0) {
 		mutex_lock(&dev->struct_mutex);
 		dev->irq_enabled = 0;
 		mutex_unlock(&dev->struct_mutex);
 	}

 	return ret;
 }
 EXPORT_SYMBOL(drm_irq_install);

 /**
  * Uninstall the IRQ handler.
  *
  * \param dev DRM device.
  *
  * Calls the driver's \c drm_driver_irq_uninstall() function, and stops the irq.
  */
 int drm_irq_uninstall(struct drm_device * dev)
 {
 	unsigned long irqflags;
 	int irq_enabled, i;

 	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 		return -EINVAL;

 	mutex_lock(&dev->struct_mutex);
 	irq_enabled = dev->irq_enabled;
 	dev->irq_enabled = 0;
 	mutex_unlock(&dev->struct_mutex);

 	/*
 	 * Wake up any waiters so they don't hang.
 	 */
 	spin_lock_irqsave(&dev->vbl_lock, irqflags);
 	for (i = 0; i < dev->num_crtcs; i++) {
 		DRM_WAKEUP(&dev->vbl_queue[i]);
 		dev->vblank_enabled[i] = 0;
 		dev->last_vblank[i] = dev->driver->get_vblank_counter(dev, i);
 	}
 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

 	if (!irq_enabled)
 		return -EINVAL;

 	DRM_DEBUG("irq=%d\n", dev->pdev->irq);

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		vga_client_register(dev->pdev, NULL, NULL, NULL);

 	dev->driver->irq_uninstall(dev);

 	free_irq(dev->pdev->irq, dev);

 	return 0;
 }
 EXPORT_SYMBOL(drm_irq_uninstall);

 /**
  * IRQ control ioctl.
  *
  * \param inode device inode.
  * \param file_priv DRM file private.
  * \param cmd command.
  * \param arg user argument, pointing to a drm_control structure.
  * \return zero on success or a negative number on failure.
  *
  * Calls irq_install() or irq_uninstall() according to \p arg.
  */
 int drm_control(struct drm_device *dev, void *data,
 		struct drm_file *file_priv)
 {
 	struct drm_control *ctl = data;

 	/* if we haven't irq we fallback for compatibility reasons - this used to be a separate function in drm_dma.h */


 	switch (ctl->func) {
 	case DRM_INST_HANDLER:
 		if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 			return 0;
 		if (drm_core_check_feature(dev, DRIVER_MODESET))
 			return 0;
 		if (dev->if_version < DRM_IF_VERSION(1, 2) &&
 		    ctl->irq != dev->pdev->irq)
 			return -EINVAL;
 		return drm_irq_install(dev);
 	case DRM_UNINST_HANDLER:
 		if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 			return 0;
 		if (drm_core_check_feature(dev, DRIVER_MODESET))
 			return 0;
 		return drm_irq_uninstall(dev);
 	default:
 		return -EINVAL;
 	}
 }

 /**
  * drm_vblank_count - retrieve "cooked" vblank counter value
  * @dev: DRM device
  * @crtc: which counter to retrieve
  *
  * Fetches the "cooked" vblank count value that represents the number of
  * vblank events since the system was booted, including lost events due to
  * modesetting activity.
  */
 u32 drm_vblank_count(struct drm_device *dev, int crtc)
 {
 	return atomic_read(&dev->_vblank_count[crtc]);
 }
 EXPORT_SYMBOL(drm_vblank_count);

 /**
  * drm_update_vblank_count - update the master vblank counter
  * @dev: DRM device
  * @crtc: counter to update
  *
  * Call back into the driver to update the appropriate vblank counter
  * (specified by @crtc).  Deal with wraparound, if it occurred, and
  * update the last read value so we can deal with wraparound on the next
  * call if necessary.
  *
  * Only necessary when going from off->on, to account for frames we
  * didn't get an interrupt for.
  *
  * Note: caller must hold dev->vbl_lock since this reads & writes
  * device vblank fields.
  */
 static void drm_update_vblank_count(struct drm_device *dev, int crtc)
 {
 	u32 cur_vblank, diff;

 	/*
 	 * Interrupts were disabled prior to this call, so deal with counter
 	 * wrap if needed.
 	 * NOTE!  It's possible we lost a full dev->max_vblank_count events
 	 * here if the register is small or we had vblank interrupts off for
 	 * a long time.
 	 */
 	cur_vblank = dev->driver->get_vblank_counter(dev, crtc);
 	diff = cur_vblank - dev->last_vblank[crtc];
 	if (cur_vblank < dev->last_vblank[crtc]) {
 		diff += dev->max_vblank_count;

 		DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
 			  crtc, dev->last_vblank[crtc], cur_vblank, diff);
 	}

 	DRM_DEBUG("enabling vblank interrupts on crtc %d, missed %d\n",
 		  crtc, diff);

 	atomic_add(diff, &dev->_vblank_count[crtc]);
 }

 /**
  * drm_vblank_get - get a reference count on vblank events
  * @dev: DRM device
  * @crtc: which CRTC to own
  *
  * Acquire a reference count on vblank events to avoid having them disabled
  * while in use.
  *
  * RETURNS
  * Zero on success, nonzero on failure.
  */
 int drm_vblank_get(struct drm_device *dev, int crtc)
 {
 	unsigned long irqflags;
 	int ret = 0;

 	spin_lock_irqsave(&dev->vbl_lock, irqflags);
 	/* Going from 0->1 means we have to enable interrupts again */
 	if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1 &&
 	    !dev->vblank_enabled[crtc]) {
 		ret = dev->driver->enable_vblank(dev, crtc);
 		DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n", crtc, ret);
 		if (ret)
 			atomic_dec(&dev->vblank_refcount[crtc]);
 		else {
 			dev->vblank_enabled[crtc] = 1;
 			drm_update_vblank_count(dev, crtc);
 		}
 	}
 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

 	return ret;
 }
 EXPORT_SYMBOL(drm_vblank_get);

 /**
  * drm_vblank_put - give up ownership of vblank events
  * @dev: DRM device
  * @crtc: which counter to give up
  *
  * Release ownership of a given vblank counter, turning off interrupts
  * if possible.
  */
 void drm_vblank_put(struct drm_device *dev, int crtc)
 {
 	BUG_ON (atomic_read (&dev->vblank_refcount[crtc]) == 0);

 	/* Last user schedules interrupt disable */
 	if (atomic_dec_and_test(&dev->vblank_refcount[crtc]))
 		mod_timer(&dev->vblank_disable_timer, jiffies + 5*DRM_HZ);
 }
 EXPORT_SYMBOL(drm_vblank_put);

 /**
  * drm_vblank_pre_modeset - account for vblanks across mode sets
  * @dev: DRM device
  * @crtc: CRTC in question
  * @post: post or pre mode set?
  *
  * Account for vblank events across mode setting events, which will likely
  * reset the hardware frame counter.
  */
 void drm_vblank_pre_modeset(struct drm_device *dev, int crtc)
 {
 	/*
 	 * To avoid all the problems that might happen if interrupts
 	 * were enabled/disabled around or between these calls, we just
 	 * have the kernel take a reference on the CRTC (just once though
 	 * to avoid corrupting the count if multiple, mismatch calls occur),
 	 * so that interrupts remain enabled in the interim.
 	 */
 	if (!dev->vblank_inmodeset[crtc]) {
 		dev->vblank_inmodeset[crtc] = 0x1;
 		if (drm_vblank_get(dev, crtc) == 0)
 			dev->vblank_inmodeset[crtc] |= 0x2;
 	}
 }
 EXPORT_SYMBOL(drm_vblank_pre_modeset);

 void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
 {
 	unsigned long irqflags;

 	if (dev->vblank_inmodeset[crtc]) {
 		spin_lock_irqsave(&dev->vbl_lock, irqflags);
 		dev->vblank_disable_allowed = 1;
 		spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

 		if (dev->vblank_inmodeset[crtc] & 0x2)
 			drm_vblank_put(dev, crtc);

 		dev->vblank_inmodeset[crtc] = 0;
 	}
 }
 EXPORT_SYMBOL(drm_vblank_post_modeset);

 /**
  * drm_modeset_ctl - handle vblank event counter changes across mode switch
  * @DRM_IOCTL_ARGS: standard ioctl arguments
  *
  * Applications should call the %_DRM_PRE_MODESET and %_DRM_POST_MODESET
  * ioctls around modesetting so that any lost vblank events are accounted for.
  *
  * Generally the counter will reset across mode sets.  If interrupts are
  * enabled around this call, we don't have to do anything since the counter
  * will have already been incremented.
  */
 int drm_modeset_ctl(struct drm_device *dev, void *data,
 		    struct drm_file *file_priv)
 {
 	struct drm_modeset_ctl *modeset = data;
 	int crtc, ret = 0;

 	/* If drm_vblank_init() hasn't been called yet, just no-op */
 	if (!dev->num_crtcs)
 		goto out;

 	crtc = modeset->crtc;
 	if (crtc >= dev->num_crtcs) {
 		ret = -EINVAL;
 		goto out;
 	}

 	switch (modeset->cmd) {
 	case _DRM_PRE_MODESET:
 		drm_vblank_pre_modeset(dev, crtc);
 		break;
 	case _DRM_POST_MODESET:
 		drm_vblank_post_modeset(dev, crtc);
 		break;
 	default:
 		ret = -EINVAL;
 		break;
 	}

 out:
 	return ret;
 }

 static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
 				  union drm_wait_vblank *vblwait,
 				  struct drm_file *file_priv)
 {
 	struct drm_pending_vblank_event *e;
 	struct timeval now;
 	unsigned long flags;
 	unsigned int seq;

 	e = kzalloc(sizeof *e, GFP_KERNEL);
 	if (e == NULL)
 		return -ENOMEM;

 	e->pipe = pipe;
 	e->event.base.type = DRM_EVENT_VBLANK;
 	e->event.base.length = sizeof e->event;
 	e->event.user_data = vblwait->request.signal;
 	e->base.event = &e->event.base;
 	e->base.file_priv = file_priv;
 	e->base.destroy = (void (*) (struct drm_pending_event *)) kfree;

 	do_gettimeofday(&now);
 	spin_lock_irqsave(&dev->event_lock, flags);

 	if (file_priv->event_space < sizeof e->event) {
 		spin_unlock_irqrestore(&dev->event_lock, flags);
 		kfree(e);
 		return -ENOMEM;
 	}

 	file_priv->event_space -= sizeof e->event;
 	seq = drm_vblank_count(dev, pipe);
 	if ((vblwait->request.type & _DRM_VBLANK_NEXTONMISS) &&
 	    (seq - vblwait->request.sequence) <= (1 << 23)) {
 		vblwait->request.sequence = seq + 1;
 	}

 	DRM_DEBUG("event on vblank count %d, current %d, crtc %d\n",
 		  vblwait->request.sequence, seq, pipe);

 	e->event.sequence = vblwait->request.sequence;
 	if ((seq - vblwait->request.sequence) <= (1 << 23)) {
 		e->event.tv_sec = now.tv_sec;
 		e->event.tv_usec = now.tv_usec;
 		drm_vblank_put(dev, e->pipe);
 		list_add_tail(&e->base.link, &e->base.file_priv->event_list);
 		wake_up_interruptible(&e->base.file_priv->event_wait);
 	} else {
 		list_add_tail(&e->base.link, &dev->vblank_event_list);
 	}

 	spin_unlock_irqrestore(&dev->event_lock, flags);

 	return 0;
 }

 /**
  * Wait for VBLANK.
  *
  * \param inode device inode.
  * \param file_priv DRM file private.
  * \param cmd command.
  * \param data user argument, pointing to a drm_wait_vblank structure.
  * \return zero on success or a negative number on failure.
  *
  * This function enables the vblank interrupt on the pipe requested, then
  * sleeps waiting for the requested sequence number to occur, and drops
  * the vblank interrupt refcount afterwards. (vblank irq disable follows that
  * after a timeout with no further vblank waits scheduled).
  */
 int drm_wait_vblank(struct drm_device *dev, void *data,
 		    struct drm_file *file_priv)
 {
 	union drm_wait_vblank *vblwait = data;
 	int ret = 0;
 	unsigned int flags, seq, crtc;

 	if ((!dev->pdev->irq) || (!dev->irq_enabled))
 		return -EINVAL;

 	if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
 		return -EINVAL;

 	if (vblwait->request.type &
 	    ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK)) {
 		DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
 			  vblwait->request.type,
 			  (_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK));
 		return -EINVAL;
 	}

 	flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
 	crtc = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;

 	if (crtc >= dev->num_crtcs)
 		return -EINVAL;

 	ret = drm_vblank_get(dev, crtc);
 	if (ret) {
 		DRM_DEBUG("failed to acquire vblank counter, %d\n", ret);
 		return ret;
 	}
 	seq = drm_vblank_count(dev, crtc);

 	switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
 	case _DRM_VBLANK_RELATIVE:
 		vblwait->request.sequence += seq;
 		vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
 	case _DRM_VBLANK_ABSOLUTE:
 		break;
 	default:
 		ret = -EINVAL;
 		goto done;
 	}

 	if (flags & _DRM_VBLANK_EVENT)
 		return drm_queue_vblank_event(dev, crtc, vblwait, file_priv);

 	if ((flags & _DRM_VBLANK_NEXTONMISS) &&
 	    (seq - vblwait->request.sequence) <= (1<<23)) {
 		vblwait->request.sequence = seq + 1;
 	}

 	DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
 		  vblwait->request.sequence, crtc);
 	dev->last_vblank_wait[crtc] = vblwait->request.sequence;
 	DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
 		    (((drm_vblank_count(dev, crtc) -
 		       vblwait->request.sequence) <= (1 << 23)) ||
 		     !dev->irq_enabled));

 	if (ret != -EINTR) {
 		struct timeval now;

 		do_gettimeofday(&now);

 		vblwait->reply.tval_sec = now.tv_sec;
 		vblwait->reply.tval_usec = now.tv_usec;
 		vblwait->reply.sequence = drm_vblank_count(dev, crtc);
 		DRM_DEBUG("returning %d to client\n",
 			  vblwait->reply.sequence);
 	} else {
 		DRM_DEBUG("vblank wait interrupted by signal\n");
 	}

 done:
 	drm_vblank_put(dev, crtc);
 	return ret;
 }

 void drm_handle_vblank_events(struct drm_device *dev, int crtc)
 {
 	struct drm_pending_vblank_event *e, *t;
 	struct timeval now;
 	unsigned long flags;
 	unsigned int seq;

 	do_gettimeofday(&now);
 	seq = drm_vblank_count(dev, crtc);

 	spin_lock_irqsave(&dev->event_lock, flags);

 	list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
 		if (e->pipe != crtc)
 			continue;
 		if ((seq - e->event.sequence) > (1<<23))
 			continue;

 		DRM_DEBUG("vblank event on %d, current %d\n",
 			  e->event.sequence, seq);

 		e->event.sequence = seq;
 		e->event.tv_sec = now.tv_sec;
 		e->event.tv_usec = now.tv_usec;
 		drm_vblank_put(dev, e->pipe);
 		list_move_tail(&e->base.link, &e->base.file_priv->event_list);
 		wake_up_interruptible(&e->base.file_priv->event_wait);
 	}

 	spin_unlock_irqrestore(&dev->event_lock, flags);
 }

 /**
  * drm_handle_vblank - handle a vblank event
  * @dev: DRM device
  * @crtc: where this event occurred
  *
  * Drivers should call this routine in their vblank interrupt handlers to
  * update the vblank counter and send any signals that may be pending.
  */
 void drm_handle_vblank(struct drm_device *dev, int crtc)
 {
 	if (!dev->num_crtcs)
 		return;

 	atomic_inc(&dev->_vblank_count[crtc]);
 	DRM_WAKEUP(&dev->vbl_queue[crtc]);
 	drm_handle_vblank_events(dev, crtc);
 }
 EXPORT_SYMBOL(drm_handle_vblank);
	/**
	* \file drm_irq.c
	* IRQ support
	*
	* \author Rickard E. (Rik) Faith <faith@valinux.com>
	* \author Gareth Hughes <gareth@valinux.com>
	*/

	/*
	* Created: Fri Mar 19 14:30:16 1999 by faith@valinux.com
	*
	* Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
	* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
	* All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice (including the next
	* paragraph) shall be included in all copies or substantial portions of the
	* Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*/

	#include "drmP.h"

	#include <linux/interrupt.h> /* For task queue support */

	#include <linux/vgaarb.h>
	/**
	* Get interrupt from bus id.
	*
	* \param inode device inode.
	* \param file_priv DRM file private.
	* \param cmd command.
	* \param arg user argument, pointing to a drm_irq_busid structure.
	* \return zero on success or a negative number on failure.
	*
	* Finds the PCI device with the specified bus id and gets its IRQ number.
	* This IOCTL is deprecated, and will now return EINVAL for any busid not equal
	* to that of the device that this DRM instance attached to.
	*/
	int drm_irq_by_busid(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_irq_busid *p = data;

	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
	return -EINVAL;

	if ((p->busnum >> 8) != drm_get_pci_domain(dev) \|\|
	(p->busnum & 0xff) != dev->pdev->bus->number \|\|
	p->devnum != PCI_SLOT(dev->pdev->devfn) \|\| p->funcnum != PCI_FUNC(dev->pdev->devfn))
	return -EINVAL;

	p->irq = dev->pdev->irq;

	DRM_DEBUG("%d:%d:%d => IRQ %d\n", p->busnum, p->devnum, p->funcnum,
	p->irq);

	return 0;
	}

	static void vblank_disable_fn(unsigned long arg)
	{
	struct drm_device dev = (struct drm_device )arg;
	unsigned long irqflags;
	int i;

	if (!dev->vblank_disable_allowed)
	return;

	for (i = 0; i < dev->num_crtcs; i++) {
	spin_lock_irqsave(&dev->vbl_lock, irqflags);
	if (atomic_read(&dev->vblank_refcount[i]) == 0 &&
	dev->vblank_enabled[i]) {
	DRM_DEBUG("disabling vblank on crtc %d\n", i);
	dev->last_vblank[i] =
	dev->driver->get_vblank_counter(dev, i);
	dev->driver->disable_vblank(dev, i);
	dev->vblank_enabled[i] = 0;
	}
	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
	}
	}

	void drm_vblank_cleanup(struct drm_device *dev)
	{
	/* Bail if the driver didn't call drm_vblank_init() */
	if (dev->num_crtcs == 0)
	return;

	del_timer(&dev->vblank_disable_timer);

	vblank_disable_fn((unsigned long)dev);

	kfree(dev->vbl_queue);
	kfree(dev->_vblank_count);
	kfree(dev->vblank_refcount);
	kfree(dev->vblank_enabled);
	kfree(dev->last_vblank);
	kfree(dev->last_vblank_wait);
	kfree(dev->vblank_inmodeset);

	dev->num_crtcs = 0;
	}

	int drm_vblank_init(struct drm_device *dev, int num_crtcs)
	{
	int i, ret = -ENOMEM;

	setup_timer(&dev->vblank_disable_timer, vblank_disable_fn,
	(unsigned long)dev);
	spin_lock_init(&dev->vbl_lock);
	dev->num_crtcs = num_crtcs;

	dev->vbl_queue = kmalloc(sizeof(wait_queue_head_t) * num_crtcs,
	GFP_KERNEL);
	if (!dev->vbl_queue)
	goto err;

	dev->_vblank_count = kmalloc(sizeof(atomic_t) * num_crtcs, GFP_KERNEL);
	if (!dev->_vblank_count)
	goto err;

	dev->vblank_refcount = kmalloc(sizeof(atomic_t) * num_crtcs,
	GFP_KERNEL);
	if (!dev->vblank_refcount)
	goto err;

	dev->vblank_enabled = kcalloc(num_crtcs, sizeof(int), GFP_KERNEL);
	if (!dev->vblank_enabled)
	goto err;

	dev->last_vblank = kcalloc(num_crtcs, sizeof(u32), GFP_KERNEL);
	if (!dev->last_vblank)
	goto err;

	dev->last_vblank_wait = kcalloc(num_crtcs, sizeof(u32), GFP_KERNEL);
	if (!dev->last_vblank_wait)
	goto err;

	dev->vblank_inmodeset = kcalloc(num_crtcs, sizeof(int), GFP_KERNEL);
	if (!dev->vblank_inmodeset)
	goto err;

	/* Zero per-crtc vblank stuff */
	for (i = 0; i < num_crtcs; i++) {
	init_waitqueue_head(&dev->vbl_queue[i]);
	atomic_set(&dev->_vblank_count[i], 0);
	atomic_set(&dev->vblank_refcount[i], 0);
	}

	dev->vblank_disable_allowed = 0;

	return 0;

	err:
	drm_vblank_cleanup(dev);
	return ret;
	}
	EXPORT_SYMBOL(drm_vblank_init);

	static void drm_irq_vgaarb_nokms(void *cookie, bool state)
	{
	struct drm_device *dev = cookie;

	if (dev->driver->vgaarb_irq) {
	dev->driver->vgaarb_irq(dev, state);
	return;
	}

	if (!dev->irq_enabled)
	return;

	if (state)
	dev->driver->irq_uninstall(dev);
	else {
	dev->driver->irq_preinstall(dev);
	dev->driver->irq_postinstall(dev);
	}
	}

	/**
	* Install IRQ handler.
	*
	* \param dev DRM device.
	*
	* Initializes the IRQ related data. Installs the handler, calling the driver
	* \c drm_driver_irq_preinstall() and \c drm_driver_irq_postinstall() functions
	* before and after the installation.
	*/
	int drm_irq_install(struct drm_device *dev)
	{
	int ret = 0;
	unsigned long sh_flags = 0;
	char *irqname;

	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
	return -EINVAL;

	if (dev->pdev->irq == 0)
	return -EINVAL;

	mutex_lock(&dev->struct_mutex);

	/* Driver must have been initialized */
	if (!dev->dev_private) {
	mutex_unlock(&dev->struct_mutex);
	return -EINVAL;
	}

	if (dev->irq_enabled) {
	mutex_unlock(&dev->struct_mutex);
	return -EBUSY;
	}
	dev->irq_enabled = 1;
	mutex_unlock(&dev->struct_mutex);

	DRM_DEBUG("irq=%d\n", dev->pdev->irq);

	/* Before installing handler */
	dev->driver->irq_preinstall(dev);

	/* Install handler */
	if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
	sh_flags = IRQF_SHARED;

	if (dev->devname)
	irqname = dev->devname;
	else
	irqname = dev->driver->name;

	ret = request_irq(drm_dev_to_irq(dev), dev->driver->irq_handler,
	sh_flags, irqname, dev);

	if (ret < 0) {
	mutex_lock(&dev->struct_mutex);
	dev->irq_enabled = 0;
	mutex_unlock(&dev->struct_mutex);
	return ret;
	}

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	vga_client_register(dev->pdev, (void *)dev, drm_irq_vgaarb_nokms, NULL);

	/* After installing handler */
	ret = dev->driver->irq_postinstall(dev);
	if (ret < 0) {
	mutex_lock(&dev->struct_mutex);
	dev->irq_enabled = 0;
	mutex_unlock(&dev->struct_mutex);
	}

	return ret;
	}
	EXPORT_SYMBOL(drm_irq_install);

	/**
	* Uninstall the IRQ handler.
	*
	* \param dev DRM device.
	*
	* Calls the driver's \c drm_driver_irq_uninstall() function, and stops the irq.
	*/
	int drm_irq_uninstall(struct drm_device * dev)
	{
	unsigned long irqflags;
	int irq_enabled, i;

	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
	return -EINVAL;

	mutex_lock(&dev->struct_mutex);
	irq_enabled = dev->irq_enabled;
	dev->irq_enabled = 0;
	mutex_unlock(&dev->struct_mutex);

	/*
	* Wake up any waiters so they don't hang.
	*/
	spin_lock_irqsave(&dev->vbl_lock, irqflags);
	for (i = 0; i < dev->num_crtcs; i++) {
	DRM_WAKEUP(&dev->vbl_queue[i]);
	dev->vblank_enabled[i] = 0;
	dev->last_vblank[i] = dev->driver->get_vblank_counter(dev, i);
	}
	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

	if (!irq_enabled)
	return -EINVAL;

	DRM_DEBUG("irq=%d\n", dev->pdev->irq);

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	vga_client_register(dev->pdev, NULL, NULL, NULL);

	dev->driver->irq_uninstall(dev);

	free_irq(dev->pdev->irq, dev);

	return 0;
	}
	EXPORT_SYMBOL(drm_irq_uninstall);

	/**
	* IRQ control ioctl.
	*
	* \param inode device inode.
	* \param file_priv DRM file private.
	* \param cmd command.
	* \param arg user argument, pointing to a drm_control structure.
	* \return zero on success or a negative number on failure.
	*
	* Calls irq_install() or irq_uninstall() according to \p arg.
	*/
	int drm_control(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_control *ctl = data;

	/* if we haven't irq we fallback for compatibility reasons - this used to be a separate function in drm_dma.h */


	switch (ctl->func) {
	case DRM_INST_HANDLER:
	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
	return 0;
	if (drm_core_check_feature(dev, DRIVER_MODESET))
	return 0;
	if (dev->if_version < DRM_IF_VERSION(1, 2) &&
	ctl->irq != dev->pdev->irq)
	return -EINVAL;
	return drm_irq_install(dev);
	case DRM_UNINST_HANDLER:
	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
	return 0;
	if (drm_core_check_feature(dev, DRIVER_MODESET))
	return 0;
	return drm_irq_uninstall(dev);
	default:
	return -EINVAL;
	}
	}

	/**
	* drm_vblank_count - retrieve "cooked" vblank counter value
	* @dev: DRM device
	* @crtc: which counter to retrieve
	*
	* Fetches the "cooked" vblank count value that represents the number of
	* vblank events since the system was booted, including lost events due to
	* modesetting activity.
	*/
	u32 drm_vblank_count(struct drm_device *dev, int crtc)
	{
	return atomic_read(&dev->_vblank_count[crtc]);
	}
	EXPORT_SYMBOL(drm_vblank_count);

	/**
	* drm_update_vblank_count - update the master vblank counter
	* @dev: DRM device
	* @crtc: counter to update
	*
	* Call back into the driver to update the appropriate vblank counter
	* (specified by @crtc). Deal with wraparound, if it occurred, and
	* update the last read value so we can deal with wraparound on the next
	* call if necessary.
	*
	* Only necessary when going from off->on, to account for frames we
	* didn't get an interrupt for.
	*
	* Note: caller must hold dev->vbl_lock since this reads & writes
	* device vblank fields.
	*/
	static void drm_update_vblank_count(struct drm_device *dev, int crtc)
	{
	u32 cur_vblank, diff;

	/*
	* Interrupts were disabled prior to this call, so deal with counter
	* wrap if needed.
	* NOTE! It's possible we lost a full dev->max_vblank_count events
	* here if the register is small or we had vblank interrupts off for
	* a long time.
	*/
	cur_vblank = dev->driver->get_vblank_counter(dev, crtc);
	diff = cur_vblank - dev->last_vblank[crtc];
	if (cur_vblank < dev->last_vblank[crtc]) {
	diff += dev->max_vblank_count;

	DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
	crtc, dev->last_vblank[crtc], cur_vblank, diff);
	}

	DRM_DEBUG("enabling vblank interrupts on crtc %d, missed %d\n",
	crtc, diff);

	atomic_add(diff, &dev->_vblank_count[crtc]);
	}

	/**
	* drm_vblank_get - get a reference count on vblank events
	* @dev: DRM device
	* @crtc: which CRTC to own
	*
	* Acquire a reference count on vblank events to avoid having them disabled
	* while in use.
	*
	* RETURNS
	* Zero on success, nonzero on failure.
	*/
	int drm_vblank_get(struct drm_device *dev, int crtc)
	{
	unsigned long irqflags;
	int ret = 0;

	spin_lock_irqsave(&dev->vbl_lock, irqflags);
	/* Going from 0->1 means we have to enable interrupts again */
	if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1 &&
	!dev->vblank_enabled[crtc]) {
	ret = dev->driver->enable_vblank(dev, crtc);
	DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n", crtc, ret);
	if (ret)
	atomic_dec(&dev->vblank_refcount[crtc]);
	else {
	dev->vblank_enabled[crtc] = 1;
	drm_update_vblank_count(dev, crtc);
	}
	}
	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

	return ret;
	}
	EXPORT_SYMBOL(drm_vblank_get);

	/**
	* drm_vblank_put - give up ownership of vblank events
	* @dev: DRM device
	* @crtc: which counter to give up
	*
	* Release ownership of a given vblank counter, turning off interrupts
	* if possible.
	*/
	void drm_vblank_put(struct drm_device *dev, int crtc)
	{
	BUG_ON (atomic_read (&dev->vblank_refcount[crtc]) == 0);

	/* Last user schedules interrupt disable */
	if (atomic_dec_and_test(&dev->vblank_refcount[crtc]))
	mod_timer(&dev->vblank_disable_timer, jiffies + 5*DRM_HZ);
	}
	EXPORT_SYMBOL(drm_vblank_put);

	/**
	* drm_vblank_pre_modeset - account for vblanks across mode sets
	* @dev: DRM device
	* @crtc: CRTC in question
	* @post: post or pre mode set?
	*
	* Account for vblank events across mode setting events, which will likely
	* reset the hardware frame counter.
	*/
	void drm_vblank_pre_modeset(struct drm_device *dev, int crtc)
	{
	/*
	* To avoid all the problems that might happen if interrupts
	* were enabled/disabled around or between these calls, we just
	* have the kernel take a reference on the CRTC (just once though
	* to avoid corrupting the count if multiple, mismatch calls occur),
	* so that interrupts remain enabled in the interim.
	*/
	if (!dev->vblank_inmodeset[crtc]) {
	dev->vblank_inmodeset[crtc] = 0x1;
	if (drm_vblank_get(dev, crtc) == 0)
	dev->vblank_inmodeset[crtc] \|= 0x2;
	}
	}
	EXPORT_SYMBOL(drm_vblank_pre_modeset);

	void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
	{
	unsigned long irqflags;

	if (dev->vblank_inmodeset[crtc]) {
	spin_lock_irqsave(&dev->vbl_lock, irqflags);
	dev->vblank_disable_allowed = 1;
	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

	if (dev->vblank_inmodeset[crtc] & 0x2)
	drm_vblank_put(dev, crtc);

	dev->vblank_inmodeset[crtc] = 0;
	}
	}
	EXPORT_SYMBOL(drm_vblank_post_modeset);

	/**
	* drm_modeset_ctl - handle vblank event counter changes across mode switch
	* @DRM_IOCTL_ARGS: standard ioctl arguments
	*
	* Applications should call the %_DRM_PRE_MODESET and %_DRM_POST_MODESET
	* ioctls around modesetting so that any lost vblank events are accounted for.
	*
	* Generally the counter will reset across mode sets. If interrupts are
	* enabled around this call, we don't have to do anything since the counter
	* will have already been incremented.
	*/
	int drm_modeset_ctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_modeset_ctl *modeset = data;
	int crtc, ret = 0;

	/* If drm_vblank_init() hasn't been called yet, just no-op */
	if (!dev->num_crtcs)
	goto out;

	crtc = modeset->crtc;
	if (crtc >= dev->num_crtcs) {
	ret = -EINVAL;
	goto out;
	}

	switch (modeset->cmd) {
	case _DRM_PRE_MODESET:
	drm_vblank_pre_modeset(dev, crtc);
	break;
	case _DRM_POST_MODESET:
	drm_vblank_post_modeset(dev, crtc);
	break;
	default:
	ret = -EINVAL;
	break;
	}

	out:
	return ret;
	}

	static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
	union drm_wait_vblank *vblwait,
	struct drm_file *file_priv)
	{
	struct drm_pending_vblank_event *e;
	struct timeval now;
	unsigned long flags;
	unsigned int seq;

	e = kzalloc(sizeof *e, GFP_KERNEL);
	if (e == NULL)
	return -ENOMEM;

	e->pipe = pipe;
	e->event.base.type = DRM_EVENT_VBLANK;
	e->event.base.length = sizeof e->event;
	e->event.user_data = vblwait->request.signal;
	e->base.event = &e->event.base;
	e->base.file_priv = file_priv;
	e->base.destroy = (void () (struct drm_pending_event )) kfree;

	do_gettimeofday(&now);
	spin_lock_irqsave(&dev->event_lock, flags);

	if (file_priv->event_space < sizeof e->event) {
	spin_unlock_irqrestore(&dev->event_lock, flags);
	kfree(e);
	return -ENOMEM;
	}

	file_priv->event_space -= sizeof e->event;
	seq = drm_vblank_count(dev, pipe);
	if ((vblwait->request.type & _DRM_VBLANK_NEXTONMISS) &&
	(seq - vblwait->request.sequence) <= (1 << 23)) {
	vblwait->request.sequence = seq + 1;
	}

	DRM_DEBUG("event on vblank count %d, current %d, crtc %d\n",
	vblwait->request.sequence, seq, pipe);

	e->event.sequence = vblwait->request.sequence;
	if ((seq - vblwait->request.sequence) <= (1 << 23)) {
	e->event.tv_sec = now.tv_sec;
	e->event.tv_usec = now.tv_usec;
	drm_vblank_put(dev, e->pipe);
	list_add_tail(&e->base.link, &e->base.file_priv->event_list);
	wake_up_interruptible(&e->base.file_priv->event_wait);
	} else {
	list_add_tail(&e->base.link, &dev->vblank_event_list);
	}

	spin_unlock_irqrestore(&dev->event_lock, flags);

	return 0;
	}

	/**
	* Wait for VBLANK.
	*
	* \param inode device inode.
	* \param file_priv DRM file private.
	* \param cmd command.
	* \param data user argument, pointing to a drm_wait_vblank structure.
	* \return zero on success or a negative number on failure.
	*
	* This function enables the vblank interrupt on the pipe requested, then
	* sleeps waiting for the requested sequence number to occur, and drops
	* the vblank interrupt refcount afterwards. (vblank irq disable follows that
	* after a timeout with no further vblank waits scheduled).
	*/
	int drm_wait_vblank(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	union drm_wait_vblank *vblwait = data;
	int ret = 0;
	unsigned int flags, seq, crtc;

	if ((!dev->pdev->irq) \|\| (!dev->irq_enabled))
	return -EINVAL;

	if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
	return -EINVAL;

	if (vblwait->request.type &
	~(_DRM_VBLANK_TYPES_MASK \| _DRM_VBLANK_FLAGS_MASK)) {
	DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
	vblwait->request.type,
	(_DRM_VBLANK_TYPES_MASK \| _DRM_VBLANK_FLAGS_MASK));
	return -EINVAL;
	}

	flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
	crtc = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;

	if (crtc >= dev->num_crtcs)
	return -EINVAL;

	ret = drm_vblank_get(dev, crtc);
	if (ret) {
	DRM_DEBUG("failed to acquire vblank counter, %d\n", ret);
	return ret;
	}
	seq = drm_vblank_count(dev, crtc);

	switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
	case _DRM_VBLANK_RELATIVE:
	vblwait->request.sequence += seq;
	vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
	case _DRM_VBLANK_ABSOLUTE:
	break;
	default:
	ret = -EINVAL;
	goto done;
	}

	if (flags & _DRM_VBLANK_EVENT)
	return drm_queue_vblank_event(dev, crtc, vblwait, file_priv);

	if ((flags & _DRM_VBLANK_NEXTONMISS) &&
	(seq - vblwait->request.sequence) <= (1<<23)) {
	vblwait->request.sequence = seq + 1;
	}

	DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
	vblwait->request.sequence, crtc);
	dev->last_vblank_wait[crtc] = vblwait->request.sequence;
	DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
	(((drm_vblank_count(dev, crtc) -
	vblwait->request.sequence) <= (1 << 23)) \|\|
	!dev->irq_enabled));

	if (ret != -EINTR) {
	struct timeval now;

	do_gettimeofday(&now);

	vblwait->reply.tval_sec = now.tv_sec;
	vblwait->reply.tval_usec = now.tv_usec;
	vblwait->reply.sequence = drm_vblank_count(dev, crtc);
	DRM_DEBUG("returning %d to client\n",
	vblwait->reply.sequence);
	} else {
	DRM_DEBUG("vblank wait interrupted by signal\n");
	}

	done:
	drm_vblank_put(dev, crtc);
	return ret;
	}

	void drm_handle_vblank_events(struct drm_device *dev, int crtc)
	{
	struct drm_pending_vblank_event e, t;
	struct timeval now;
	unsigned long flags;
	unsigned int seq;

	do_gettimeofday(&now);
	seq = drm_vblank_count(dev, crtc);

	spin_lock_irqsave(&dev->event_lock, flags);

	list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
	if (e->pipe != crtc)
	continue;
	if ((seq - e->event.sequence) > (1<<23))
	continue;

	DRM_DEBUG("vblank event on %d, current %d\n",
	e->event.sequence, seq);

	e->event.sequence = seq;
	e->event.tv_sec = now.tv_sec;
	e->event.tv_usec = now.tv_usec;
	drm_vblank_put(dev, e->pipe);
	list_move_tail(&e->base.link, &e->base.file_priv->event_list);
	wake_up_interruptible(&e->base.file_priv->event_wait);
	}

	spin_unlock_irqrestore(&dev->event_lock, flags);
	}

	/**
	* drm_handle_vblank - handle a vblank event
	* @dev: DRM device
	* @crtc: where this event occurred
	*
	* Drivers should call this routine in their vblank interrupt handlers to
	* update the vblank counter and send any signals that may be pending.
	*/
	void drm_handle_vblank(struct drm_device *dev, int crtc)
	{
	if (!dev->num_crtcs)
	return;

	atomic_inc(&dev->_vblank_count[crtc]);
	DRM_WAKEUP(&dev->vbl_queue[crtc]);
	drm_handle_vblank_events(dev, crtc);
	}
	EXPORT_SYMBOL(drm_handle_vblank);