drm_irq.c 38.8 KB
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/**
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 * \file drm_irq.c
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 * 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"
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#include "drm_trace.h"
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#include <linux/interrupt.h>	/* For task queue support */
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#include <linux/slab.h>
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#include <linux/vgaarb.h>
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/* Access macro for slots in vblank timestamp ringbuffer. */
#define vblanktimestamp(dev, crtc, count) ( \
	(dev)->_vblank_time[(crtc) * DRM_VBLANKTIME_RBSIZE + \
	((count) % DRM_VBLANKTIME_RBSIZE)])

/* Retry timestamp calculation up to 3 times to satisfy
 * drm_timestamp_precision before giving up.
 */
#define DRM_TIMESTAMP_MAXRETRIES 3

/* Threshold in nanoseconds for detection of redundant
 * vblank irq in drm_handle_vblank(). 1 msec should be ok.
 */
#define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000

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/**
 * Get interrupt from bus id.
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 *
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 * \param inode device inode.
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 * \param file_priv DRM file private.
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 * \param cmd command.
 * \param arg user argument, pointing to a drm_irq_busid structure.
 * \return zero on success or a negative number on failure.
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 *
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 * 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.
 */
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int drm_irq_by_busid(struct drm_device *dev, void *data,
		     struct drm_file *file_priv)
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{
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	struct drm_irq_busid *p = data;
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	if (drm_core_check_feature(dev, DRIVER_USE_PLATFORM_DEVICE))
		return -EINVAL;

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

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	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))
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		return -EINVAL;

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	p->irq = dev->pdev->irq;
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	DRM_DEBUG("%d:%d:%d => IRQ %d\n", p->busnum, p->devnum, p->funcnum,
		  p->irq);
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	return 0;
}

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/*
 * Clear vblank timestamp buffer for a crtc.
 */
static void clear_vblank_timestamps(struct drm_device *dev, int crtc)
{
	memset(&dev->_vblank_time[crtc * DRM_VBLANKTIME_RBSIZE], 0,
		DRM_VBLANKTIME_RBSIZE * sizeof(struct timeval));
}

/*
 * Disable vblank irq's on crtc, make sure that last vblank count
 * of hardware and corresponding consistent software vblank counter
 * are preserved, even if there are any spurious vblank irq's after
 * disable.
 */
static void vblank_disable_and_save(struct drm_device *dev, int crtc)
{
	unsigned long irqflags;
	u32 vblcount;
	s64 diff_ns;
	int vblrc;
	struct timeval tvblank;

	/* Prevent vblank irq processing while disabling vblank irqs,
	 * so no updates of timestamps or count can happen after we've
	 * disabled. Needed to prevent races in case of delayed irq's.
	 * Disable preemption, so vblank_time_lock is held as short as
	 * possible, even under a kernel with PREEMPT_RT patches.
	 */
	preempt_disable();
	spin_lock_irqsave(&dev->vblank_time_lock, irqflags);

	dev->driver->disable_vblank(dev, crtc);
	dev->vblank_enabled[crtc] = 0;

	/* No further vblank irq's will be processed after
	 * this point. Get current hardware vblank count and
	 * vblank timestamp, repeat until they are consistent.
	 *
	 * FIXME: There is still a race condition here and in
	 * drm_update_vblank_count() which can cause off-by-one
	 * reinitialization of software vblank counter. If gpu
	 * vblank counter doesn't increment exactly at the leading
	 * edge of a vblank interval, then we can lose 1 count if
	 * we happen to execute between start of vblank and the
	 * delayed gpu counter increment.
	 */
	do {
		dev->last_vblank[crtc] = dev->driver->get_vblank_counter(dev, crtc);
		vblrc = drm_get_last_vbltimestamp(dev, crtc, &tvblank, 0);
	} while (dev->last_vblank[crtc] != dev->driver->get_vblank_counter(dev, crtc));

	/* Compute time difference to stored timestamp of last vblank
	 * as updated by last invocation of drm_handle_vblank() in vblank irq.
	 */
	vblcount = atomic_read(&dev->_vblank_count[crtc]);
	diff_ns = timeval_to_ns(&tvblank) -
		  timeval_to_ns(&vblanktimestamp(dev, crtc, vblcount));

	/* If there is at least 1 msec difference between the last stored
	 * timestamp and tvblank, then we are currently executing our
	 * disable inside a new vblank interval, the tvblank timestamp
	 * corresponds to this new vblank interval and the irq handler
	 * for this vblank didn't run yet and won't run due to our disable.
	 * Therefore we need to do the job of drm_handle_vblank() and
	 * increment the vblank counter by one to account for this vblank.
	 *
	 * Skip this step if there isn't any high precision timestamp
	 * available. In that case we can't account for this and just
	 * hope for the best.
	 */
	if ((vblrc > 0) && (abs(diff_ns) > 1000000))
		atomic_inc(&dev->_vblank_count[crtc]);

	/* Invalidate all timestamps while vblank irq's are off. */
	clear_vblank_timestamps(dev, crtc);

	spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
	preempt_enable();
}

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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);
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			vblank_disable_and_save(dev, i);
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		}
		spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
	}
}

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void drm_vblank_cleanup(struct drm_device *dev)
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{
	/* 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);

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	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);
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	kfree(dev->_vblank_time);
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	dev->num_crtcs = 0;
}
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EXPORT_SYMBOL(drm_vblank_cleanup);
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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);
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	spin_lock_init(&dev->vblank_time_lock);

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	dev->num_crtcs = num_crtcs;

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

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

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

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

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

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

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

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	dev->_vblank_time = kcalloc(num_crtcs * DRM_VBLANKTIME_RBSIZE,
				    sizeof(struct timeval), GFP_KERNEL);
	if (!dev->_vblank_time)
		goto err;

	DRM_INFO("Supports vblank timestamp caching Rev 1 (10.10.2010).\n");

	/* Driver specific high-precision vblank timestamping supported? */
	if (dev->driver->get_vblank_timestamp)
		DRM_INFO("Driver supports precise vblank timestamp query.\n");
	else
		DRM_INFO("No driver support for vblank timestamp query.\n");

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	/* 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);

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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);
	}
}

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

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	if (drm_dev_to_irq(dev) == 0)
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		return -EINVAL;

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

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	if (dev->irq_enabled) {
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		mutex_unlock(&dev->struct_mutex);
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		return -EBUSY;
	}
	dev->irq_enabled = 1;
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	mutex_unlock(&dev->struct_mutex);
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	DRM_DEBUG("irq=%d\n", drm_dev_to_irq(dev));
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	/* Before installing handler */
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	dev->driver->irq_preinstall(dev);

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	/* Install handler */
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	if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
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		sh_flags = IRQF_SHARED;
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	if (dev->devname)
		irqname = dev->devname;
	else
		irqname = dev->driver->name;

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	ret = request_irq(drm_dev_to_irq(dev), dev->driver->irq_handler,
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			  sh_flags, irqname, dev);
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	if (ret < 0) {
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		mutex_lock(&dev->struct_mutex);
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		dev->irq_enabled = 0;
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		mutex_unlock(&dev->struct_mutex);
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		return ret;
	}

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

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	/* After installing handler */
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	ret = dev->driver->irq_postinstall(dev);
	if (ret < 0) {
		mutex_lock(&dev->struct_mutex);
		dev->irq_enabled = 0;
		mutex_unlock(&dev->struct_mutex);
	}
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	return ret;
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}
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EXPORT_SYMBOL(drm_irq_install);
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/**
 * Uninstall the IRQ handler.
 *
 * \param dev DRM device.
 *
 * Calls the driver's \c drm_driver_irq_uninstall() function, and stops the irq.
 */
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int drm_irq_uninstall(struct drm_device *dev)
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{
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	unsigned long irqflags;
	int irq_enabled, i;
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	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
		return -EINVAL;

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	mutex_lock(&dev->struct_mutex);
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	irq_enabled = dev->irq_enabled;
	dev->irq_enabled = 0;
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	mutex_unlock(&dev->struct_mutex);
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	/*
	 * 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;
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		dev->last_vblank[i] = dev->driver->get_vblank_counter(dev, i);
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	}
	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);

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	if (!irq_enabled)
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		return -EINVAL;

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	DRM_DEBUG("irq=%d\n", drm_dev_to_irq(dev));
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	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		vga_client_register(dev->pdev, NULL, NULL, NULL);

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	dev->driver->irq_uninstall(dev);

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	free_irq(drm_dev_to_irq(dev), dev);
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	return 0;
}
EXPORT_SYMBOL(drm_irq_uninstall);

/**
 * IRQ control ioctl.
 *
 * \param inode device inode.
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 * \param file_priv DRM file private.
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 * \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.
 */
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int drm_control(struct drm_device *dev, void *data,
		struct drm_file *file_priv)
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{
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	struct drm_control *ctl = data;
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	/* if we haven't irq we fallback for compatibility reasons -
	 * this used to be a separate function in drm_dma.h
	 */
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	switch (ctl->func) {
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	case DRM_INST_HANDLER:
		if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
			return 0;
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		if (drm_core_check_feature(dev, DRIVER_MODESET))
			return 0;
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		if (dev->if_version < DRM_IF_VERSION(1, 2) &&
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		    ctl->irq != drm_dev_to_irq(dev))
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			return -EINVAL;
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		return drm_irq_install(dev);
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	case DRM_UNINST_HANDLER:
		if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
			return 0;
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		if (drm_core_check_feature(dev, DRIVER_MODESET))
			return 0;
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		return drm_irq_uninstall(dev);
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	default:
		return -EINVAL;
	}
}

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/**
 * drm_calc_timestamping_constants - Calculate and
 * store various constants which are later needed by
 * vblank and swap-completion timestamping, e.g, by
 * drm_calc_vbltimestamp_from_scanoutpos().
 * They are derived from crtc's true scanout timing,
 * so they take things like panel scaling or other
 * adjustments into account.
 *
 * @crtc drm_crtc whose timestamp constants should be updated.
 *
 */
void drm_calc_timestamping_constants(struct drm_crtc *crtc)
{
	s64 linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;
	u64 dotclock;

	/* Dot clock in Hz: */
	dotclock = (u64) crtc->hwmode.clock * 1000;

	/* Valid dotclock? */
	if (dotclock > 0) {
		/* Convert scanline length in pixels and video dot clock to
		 * line duration, frame duration and pixel duration in
		 * nanoseconds:
		 */
		pixeldur_ns = (s64) div64_u64(1000000000, dotclock);
		linedur_ns  = (s64) div64_u64(((u64) crtc->hwmode.crtc_htotal *
					      1000000000), dotclock);
		framedur_ns = (s64) crtc->hwmode.crtc_vtotal * linedur_ns;
	} else
		DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",
			  crtc->base.id);

	crtc->pixeldur_ns = pixeldur_ns;
	crtc->linedur_ns  = linedur_ns;
	crtc->framedur_ns = framedur_ns;

	DRM_DEBUG("crtc %d: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
		  crtc->base.id, crtc->hwmode.crtc_htotal,
		  crtc->hwmode.crtc_vtotal, crtc->hwmode.crtc_vdisplay);
	DRM_DEBUG("crtc %d: clock %d kHz framedur %d linedur %d, pixeldur %d\n",
		  crtc->base.id, (int) dotclock/1000, (int) framedur_ns,
		  (int) linedur_ns, (int) pixeldur_ns);
}
EXPORT_SYMBOL(drm_calc_timestamping_constants);

/**
 * drm_calc_vbltimestamp_from_scanoutpos - helper routine for kms
 * drivers. Implements calculation of exact vblank timestamps from
 * given drm_display_mode timings and current video scanout position
 * of a crtc. This can be called from within get_vblank_timestamp()
 * implementation of a kms driver to implement the actual timestamping.
 *
 * Should return timestamps conforming to the OML_sync_control OpenML
 * extension specification. The timestamp corresponds to the end of
 * the vblank interval, aka start of scanout of topmost-leftmost display
 * pixel in the following video frame.
 *
 * Requires support for optional dev->driver->get_scanout_position()
 * in kms driver, plus a bit of setup code to provide a drm_display_mode
 * that corresponds to the true scanout timing.
 *
 * The current implementation only handles standard video modes. It
 * returns as no operation if a doublescan or interlaced video mode is
 * active. Higher level code is expected to handle this.
 *
 * @dev: DRM device.
 * @crtc: Which crtc's vblank timestamp to retrieve.
 * @max_error: Desired maximum allowable error in timestamps (nanosecs).
 *             On return contains true maximum error of timestamp.
 * @vblank_time: Pointer to struct timeval which should receive the timestamp.
 * @flags: Flags to pass to driver:
 *         0 = Default.
 *         DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler.
 * @refcrtc: drm_crtc* of crtc which defines scanout timing.
 *
 * Returns negative value on error, failure or if not supported in current
 * video mode:
 *
 * -EINVAL   - Invalid crtc.
 * -EAGAIN   - Temporary unavailable, e.g., called before initial modeset.
 * -ENOTSUPP - Function not supported in current display mode.
 * -EIO      - Failed, e.g., due to failed scanout position query.
 *
 * Returns or'ed positive status flags on success:
 *
 * DRM_VBLANKTIME_SCANOUTPOS_METHOD - Signal this method used for timestamping.
 * DRM_VBLANKTIME_INVBL - Timestamp taken while scanout was in vblank interval.
 *
 */
int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
					  int *max_error,
					  struct timeval *vblank_time,
					  unsigned flags,
					  struct drm_crtc *refcrtc)
{
	struct timeval stime, raw_time;
	struct drm_display_mode *mode;
	int vbl_status, vtotal, vdisplay;
	int vpos, hpos, i;
	s64 framedur_ns, linedur_ns, pixeldur_ns, delta_ns, duration_ns;
	bool invbl;

	if (crtc < 0 || crtc >= dev->num_crtcs) {
		DRM_ERROR("Invalid crtc %d\n", crtc);
		return -EINVAL;
	}

	/* Scanout position query not supported? Should not happen. */
	if (!dev->driver->get_scanout_position) {
		DRM_ERROR("Called from driver w/o get_scanout_position()!?\n");
		return -EIO;
	}

	mode = &refcrtc->hwmode;
	vtotal = mode->crtc_vtotal;
	vdisplay = mode->crtc_vdisplay;

	/* Durations of frames, lines, pixels in nanoseconds. */
	framedur_ns = refcrtc->framedur_ns;
	linedur_ns  = refcrtc->linedur_ns;
	pixeldur_ns = refcrtc->pixeldur_ns;

	/* If mode timing undefined, just return as no-op:
	 * Happens during initial modesetting of a crtc.
	 */
	if (vtotal <= 0 || vdisplay <= 0 || framedur_ns == 0) {
		DRM_DEBUG("crtc %d: Noop due to uninitialized mode.\n", crtc);
		return -EAGAIN;
	}

	/* Don't know yet how to handle interlaced or
	 * double scan modes. Just no-op for now.
	 */
	if (mode->flags & (DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLSCAN)) {
		DRM_DEBUG("crtc %d: Noop due to unsupported mode.\n", crtc);
		return -ENOTSUPP;
	}

	/* Get current scanout position with system timestamp.
	 * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
	 * if single query takes longer than max_error nanoseconds.
	 *
	 * This guarantees a tight bound on maximum error if
	 * code gets preempted or delayed for some reason.
	 */
	for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
		/* Disable preemption to make it very likely to
		 * succeed in the first iteration even on PREEMPT_RT kernel.
		 */
		preempt_disable();

		/* Get system timestamp before query. */
		do_gettimeofday(&stime);

		/* Get vertical and horizontal scanout pos. vpos, hpos. */
		vbl_status = dev->driver->get_scanout_position(dev, crtc, &vpos, &hpos);

		/* Get system timestamp after query. */
		do_gettimeofday(&raw_time);

		preempt_enable();

		/* Return as no-op if scanout query unsupported or failed. */
		if (!(vbl_status & DRM_SCANOUTPOS_VALID)) {
			DRM_DEBUG("crtc %d : scanoutpos query failed [%d].\n",
				  crtc, vbl_status);
			return -EIO;
		}

		duration_ns = timeval_to_ns(&raw_time) - timeval_to_ns(&stime);

		/* Accept result with <  max_error nsecs timing uncertainty. */
		if (duration_ns <= (s64) *max_error)
			break;
	}

	/* Noisy system timing? */
	if (i == DRM_TIMESTAMP_MAXRETRIES) {
		DRM_DEBUG("crtc %d: Noisy timestamp %d us > %d us [%d reps].\n",
			  crtc, (int) duration_ns/1000, *max_error/1000, i);
	}

	/* Return upper bound of timestamp precision error. */
	*max_error = (int) duration_ns;

	/* Check if in vblank area:
	 * vpos is >=0 in video scanout area, but negative
	 * within vblank area, counting down the number of lines until
	 * start of scanout.
	 */
	invbl = vbl_status & DRM_SCANOUTPOS_INVBL;

	/* Convert scanout position into elapsed time at raw_time query
	 * since start of scanout at first display scanline. delta_ns
	 * can be negative if start of scanout hasn't happened yet.
	 */
	delta_ns = (s64) vpos * linedur_ns + (s64) hpos * pixeldur_ns;

	/* Is vpos outside nominal vblank area, but less than
	 * 1/100 of a frame height away from start of vblank?
	 * If so, assume this isn't a massively delayed vblank
	 * interrupt, but a vblank interrupt that fired a few
	 * microseconds before true start of vblank. Compensate
	 * by adding a full frame duration to the final timestamp.
	 * Happens, e.g., on ATI R500, R600.
	 *
	 * We only do this if DRM_CALLED_FROM_VBLIRQ.
	 */
	if ((flags & DRM_CALLED_FROM_VBLIRQ) && !invbl &&
	    ((vdisplay - vpos) < vtotal / 100)) {
		delta_ns = delta_ns - framedur_ns;

		/* Signal this correction as "applied". */
		vbl_status |= 0x8;
	}

	/* Subtract time delta from raw timestamp to get final
	 * vblank_time timestamp for end of vblank.
	 */
	*vblank_time = ns_to_timeval(timeval_to_ns(&raw_time) - delta_ns);

	DRM_DEBUG("crtc %d : v %d p(%d,%d)@ %d.%d -> %d.%d [e %d us, %d rep]\n",
		  crtc, (int) vbl_status, hpos, vpos, raw_time.tv_sec,
		  raw_time.tv_usec, vblank_time->tv_sec, vblank_time->tv_usec,
		  (int) duration_ns/1000, i);

	vbl_status = DRM_VBLANKTIME_SCANOUTPOS_METHOD;
	if (invbl)
		vbl_status |= DRM_VBLANKTIME_INVBL;

	return vbl_status;
}
EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos);

/**
 * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
 * vblank interval.
 *
 * @dev: DRM device
 * @crtc: which crtc's vblank timestamp to retrieve
 * @tvblank: Pointer to target struct timeval which should receive the timestamp
 * @flags: Flags to pass to driver:
 *         0 = Default.
 *         DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler.
 *
 * Fetches the system timestamp corresponding to the time of the most recent
 * vblank interval on specified crtc. May call into kms-driver to
 * compute the timestamp with a high-precision GPU specific method.
 *
 * Returns zero if timestamp originates from uncorrected do_gettimeofday()
 * call, i.e., it isn't very precisely locked to the true vblank.
 *
 * Returns non-zero if timestamp is considered to be very precise.
 */
u32 drm_get_last_vbltimestamp(struct drm_device *dev, int crtc,
			      struct timeval *tvblank, unsigned flags)
{
	int ret = 0;

	/* Define requested maximum error on timestamps (nanoseconds). */
	int max_error = (int) drm_timestamp_precision * 1000;

	/* Query driver if possible and precision timestamping enabled. */
	if (dev->driver->get_vblank_timestamp && (max_error > 0)) {
		ret = dev->driver->get_vblank_timestamp(dev, crtc, &max_error,
							tvblank, flags);
		if (ret > 0)
			return (u32) ret;
	}

	/* GPU high precision timestamp query unsupported or failed.
	 * Return gettimeofday timestamp as best estimate.
	 */
	do_gettimeofday(tvblank);

	return 0;
}
EXPORT_SYMBOL(drm_get_last_vbltimestamp);

755 756 757 758 759 760 761 762 763 764 765 766 767 768 769
/**
 * 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);

770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803
/**
 * drm_vblank_count_and_time - retrieve "cooked" vblank counter value
 * and the system timestamp corresponding to that vblank counter value.
 *
 * @dev: DRM device
 * @crtc: which counter to retrieve
 * @vblanktime: Pointer to struct timeval to receive the vblank timestamp.
 *
 * 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. Returns corresponding system timestamp of the time
 * of the vblank interval that corresponds to the current value vblank counter
 * value.
 */
u32 drm_vblank_count_and_time(struct drm_device *dev, int crtc,
			      struct timeval *vblanktime)
{
	u32 cur_vblank;

	/* Read timestamp from slot of _vblank_time ringbuffer
	 * that corresponds to current vblank count. Retry if
	 * count has incremented during readout. This works like
	 * a seqlock.
	 */
	do {
		cur_vblank = atomic_read(&dev->_vblank_count[crtc]);
		*vblanktime = vblanktimestamp(dev, crtc, cur_vblank);
		smp_rmb();
	} while (cur_vblank != atomic_read(&dev->_vblank_count[crtc]));

	return cur_vblank;
}
EXPORT_SYMBOL(drm_vblank_count_and_time);

804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821
/**
 * 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)
{
822 823
	u32 cur_vblank, diff, tslot, rc;
	struct timeval t_vblank;
824 825 826 827 828 829 830

	/*
	 * 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.
831 832 833 834 835
	 *
	 * We repeat the hardware vblank counter & timestamp query until
	 * we get consistent results. This to prevent races between gpu
	 * updating its hardware counter while we are retrieving the
	 * corresponding vblank timestamp.
836
	 */
837 838 839 840 841 842
	do {
		cur_vblank = dev->driver->get_vblank_counter(dev, crtc);
		rc = drm_get_last_vbltimestamp(dev, crtc, &t_vblank, 0);
	} while (cur_vblank != dev->driver->get_vblank_counter(dev, crtc));

	/* Deal with counter wrap */
843 844 845 846 847 848 849 850 851 852 853
	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);

854 855 856 857 858 859 860 861 862 863
	/* Reinitialize corresponding vblank timestamp if high-precision query
	 * available. Skip this step if query unsupported or failed. Will
	 * reinitialize delayed at next vblank interrupt in that case.
	 */
	if (rc) {
		tslot = atomic_read(&dev->_vblank_count[crtc]) + diff;
		vblanktimestamp(dev, crtc, tslot) = t_vblank;
		smp_wmb();
	}

864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879
	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)
{
880
	unsigned long irqflags, irqflags2;
881 882 883 884
	int ret = 0;

	spin_lock_irqsave(&dev->vbl_lock, irqflags);
	/* Going from 0->1 means we have to enable interrupts again */
885
	if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) {
886 887 888 889 890
		/* Disable preemption while holding vblank_time_lock. Do
		 * it explicitely to guard against PREEMPT_RT kernel.
		 */
		preempt_disable();
		spin_lock_irqsave(&dev->vblank_time_lock, irqflags2);
891
		if (!dev->vblank_enabled[crtc]) {
892 893 894 895 896 897
			/* Enable vblank irqs under vblank_time_lock protection.
			 * All vblank count & timestamp updates are held off
			 * until we are done reinitializing master counter and
			 * timestamps. Filtercode in drm_handle_vblank() will
			 * prevent double-accounting of same vblank interval.
			 */
898
			ret = dev->driver->enable_vblank(dev, crtc);
899 900
			DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n",
				  crtc, ret);
901 902 903 904 905 906 907
			if (ret)
				atomic_dec(&dev->vblank_refcount[crtc]);
			else {
				dev->vblank_enabled[crtc] = 1;
				drm_update_vblank_count(dev, crtc);
			}
		}
908 909
		spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags2);
		preempt_enable();
910 911
	} else {
		if (!dev->vblank_enabled[crtc]) {
912
			atomic_dec(&dev->vblank_refcount[crtc]);
913
			ret = -EINVAL;
914 915 916 917 918 919 920 921 922 923 924 925 926 927
		}
	}
	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
928
 * if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
929 930 931
 */
void drm_vblank_put(struct drm_device *dev, int crtc)
{
932
	BUG_ON(atomic_read(&dev->vblank_refcount[crtc]) == 0);
933

934
	/* Last user schedules interrupt disable */
935 936 937 938
	if (atomic_dec_and_test(&dev->vblank_refcount[crtc]) &&
	    (drm_vblank_offdelay > 0))
		mod_timer(&dev->vblank_disable_timer,
			  jiffies + ((drm_vblank_offdelay * DRM_HZ)/1000));
939 940 941
}
EXPORT_SYMBOL(drm_vblank_put);

942 943 944 945 946
void drm_vblank_off(struct drm_device *dev, int crtc)
{
	unsigned long irqflags;

	spin_lock_irqsave(&dev->vbl_lock, irqflags);
947
	vblank_disable_and_save(dev, crtc);
948 949 950 951 952
	DRM_WAKEUP(&dev->vbl_queue[crtc]);
	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
}
EXPORT_SYMBOL(drm_vblank_off);

D
Dave Airlie 已提交
953 954 955 956 957 958 959 960 961 962 963
/**
 * 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)
{
964 965 966
	/* vblank is not initialized (IRQ not installed ?) */
	if (!dev->num_crtcs)
		return;
D
Dave Airlie 已提交
967 968 969 970 971 972 973 974
	/*
	 * 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]) {
975 976 977
		dev->vblank_inmodeset[crtc] = 0x1;
		if (drm_vblank_get(dev, crtc) == 0)
			dev->vblank_inmodeset[crtc] |= 0x2;
D
Dave Airlie 已提交
978 979 980 981 982 983 984 985 986 987 988 989
	}
}
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);
990 991 992 993 994

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

		dev->vblank_inmodeset[crtc] = 0;
D
Dave Airlie 已提交
995 996 997 998
	}
}
EXPORT_SYMBOL(drm_vblank_post_modeset);

999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027
/**
 * 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:
D
Dave Airlie 已提交
1028
		drm_vblank_pre_modeset(dev, crtc);
1029 1030
		break;
	case _DRM_POST_MODESET:
D
Dave Airlie 已提交
1031
		drm_vblank_post_modeset(dev, crtc);
1032 1033 1034 1035 1036 1037 1038 1039 1040 1041
		break;
	default:
		ret = -EINVAL;
		break;
	}

out:
	return ret;
}

1042 1043 1044 1045 1046 1047 1048 1049
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;
1050
	int ret;
1051 1052

	e = kzalloc(sizeof *e, GFP_KERNEL);
1053 1054 1055 1056
	if (e == NULL) {
		ret = -ENOMEM;
		goto err_put;
	}
1057 1058

	e->pipe = pipe;
1059
	e->base.pid = current->pid;
1060 1061 1062 1063 1064 1065 1066 1067 1068 1069
	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;

	spin_lock_irqsave(&dev->event_lock, flags);

	if (file_priv->event_space < sizeof e->event) {
1070 1071
		ret = -EBUSY;
		goto err_unlock;
1072 1073 1074
	}

	file_priv->event_space -= sizeof e->event;
1075 1076
	seq = drm_vblank_count_and_time(dev, pipe, &now);

1077 1078 1079
	if ((vblwait->request.type & _DRM_VBLANK_NEXTONMISS) &&
	    (seq - vblwait->request.sequence) <= (1 << 23)) {
		vblwait->request.sequence = seq + 1;
1080
		vblwait->reply.sequence = vblwait->request.sequence;
1081 1082 1083 1084 1085
	}

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

1086 1087 1088
	trace_drm_vblank_event_queued(current->pid, pipe,
				      vblwait->request.sequence);

1089 1090
	e->event.sequence = vblwait->request.sequence;
	if ((seq - vblwait->request.sequence) <= (1 << 23)) {
1091
		e->event.sequence = seq;
1092 1093
		e->event.tv_sec = now.tv_sec;
		e->event.tv_usec = now.tv_usec;
1094
		drm_vblank_put(dev, pipe);
1095 1096
		list_add_tail(&e->base.link, &e->base.file_priv->event_list);
		wake_up_interruptible(&e->base.file_priv->event_wait);
1097
		vblwait->reply.sequence = seq;
1098 1099
		trace_drm_vblank_event_delivered(current->pid, pipe,
						 vblwait->request.sequence);
1100 1101
	} else {
		list_add_tail(&e->base.link, &dev->vblank_event_list);
1102
		vblwait->reply.sequence = vblwait->request.sequence;
1103 1104 1105 1106 1107
	}

	spin_unlock_irqrestore(&dev->event_lock, flags);

	return 0;
1108 1109 1110 1111 1112

err_unlock:
	spin_unlock_irqrestore(&dev->event_lock, flags);
	kfree(e);
err_put:
1113
	drm_vblank_put(dev, pipe);
1114
	return ret;
1115 1116
}

L
Linus Torvalds 已提交
1117 1118 1119 1120
/**
 * Wait for VBLANK.
 *
 * \param inode device inode.
1121
 * \param file_priv DRM file private.
L
Linus Torvalds 已提交
1122 1123 1124 1125
 * \param cmd command.
 * \param data user argument, pointing to a drm_wait_vblank structure.
 * \return zero on success or a negative number on failure.
 *
1126 1127 1128 1129
 * 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).
L
Linus Torvalds 已提交
1130
 */
1131 1132
int drm_wait_vblank(struct drm_device *dev, void *data,
		    struct drm_file *file_priv)
L
Linus Torvalds 已提交
1133
{
1134
	union drm_wait_vblank *vblwait = data;
L
Linus Torvalds 已提交
1135
	int ret = 0;
1136
	unsigned int flags, seq, crtc;
L
Linus Torvalds 已提交
1137

1138
	if ((!drm_dev_to_irq(dev)) || (!dev->irq_enabled))
L
Linus Torvalds 已提交
1139 1140
		return -EINVAL;

1141 1142 1143
	if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
		return -EINVAL;

1144
	if (vblwait->request.type &
1145 1146
	    ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK)) {
		DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
1147
			  vblwait->request.type,
1148 1149 1150 1151
			  (_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK));
		return -EINVAL;
	}

1152
	flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
1153
	crtc = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;
1154

1155
	if (crtc >= dev->num_crtcs)
1156 1157
		return -EINVAL;

1158 1159
	ret = drm_vblank_get(dev, crtc);
	if (ret) {
1160
		DRM_DEBUG("failed to acquire vblank counter, %d\n", ret);
1161 1162 1163
		return ret;
	}
	seq = drm_vblank_count(dev, crtc);
1164

1165
	switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
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1166
	case _DRM_VBLANK_RELATIVE:
1167 1168
		vblwait->request.sequence += seq;
		vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
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1169 1170 1171
	case _DRM_VBLANK_ABSOLUTE:
		break;
	default:
1172 1173
		ret = -EINVAL;
		goto done;
L
Linus Torvalds 已提交
1174 1175
	}

1176 1177 1178
	if (flags & _DRM_VBLANK_EVENT)
		return drm_queue_vblank_event(dev, crtc, vblwait, file_priv);

1179
	if ((flags & _DRM_VBLANK_NEXTONMISS) &&
1180 1181
	    (seq - vblwait->request.sequence) <= (1<<23)) {
		vblwait->request.sequence = seq + 1;
1182 1183
	}

1184 1185 1186 1187 1188 1189 1190
	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));
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1191

1192 1193
	if (ret != -EINTR) {
		struct timeval now;
L
Linus Torvalds 已提交
1194

1195
		vblwait->reply.sequence = drm_vblank_count_and_time(dev, crtc, &now);
1196 1197
		vblwait->reply.tval_sec = now.tv_sec;
		vblwait->reply.tval_usec = now.tv_usec;
1198

1199 1200
		DRM_DEBUG("returning %d to client\n",
			  vblwait->reply.sequence);
L
Linus Torvalds 已提交
1201
	} else {
1202
		DRM_DEBUG("vblank wait interrupted by signal\n");
L
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1203 1204
	}

1205 1206
done:
	drm_vblank_put(dev, crtc);
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1207 1208 1209
	return ret;
}

1210 1211 1212 1213 1214 1215 1216
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;

1217
	seq = drm_vblank_count_and_time(dev, crtc, &now);
1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235

	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);
1236 1237
		trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
						 e->event.sequence);
1238 1239 1240
	}

	spin_unlock_irqrestore(&dev->event_lock, flags);
J
Jesse Barnes 已提交
1241 1242

	trace_drm_vblank_event(crtc, seq);
1243 1244
}

1245 1246 1247 1248 1249 1250 1251 1252
/**
 * 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.
 */
1253
bool drm_handle_vblank(struct drm_device *dev, int crtc)
1254
{
1255 1256 1257 1258 1259
	u32 vblcount;
	s64 diff_ns;
	struct timeval tvblank;
	unsigned long irqflags;

1260
	if (!dev->num_crtcs)
1261
		return false;
1262

1263 1264 1265 1266 1267 1268 1269 1270 1271
	/* Need timestamp lock to prevent concurrent execution with
	 * vblank enable/disable, as this would cause inconsistent
	 * or corrupted timestamps and vblank counts.
	 */
	spin_lock_irqsave(&dev->vblank_time_lock, irqflags);

	/* Vblank irq handling disabled. Nothing to do. */
	if (!dev->vblank_enabled[crtc]) {
		spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
1272
		return false;
1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
	}

	/* Fetch corresponding timestamp for this vblank interval from
	 * driver and store it in proper slot of timestamp ringbuffer.
	 */

	/* Get current timestamp and count. */
	vblcount = atomic_read(&dev->_vblank_count[crtc]);
	drm_get_last_vbltimestamp(dev, crtc, &tvblank, DRM_CALLED_FROM_VBLIRQ);

	/* Compute time difference to timestamp of last vblank */
	diff_ns = timeval_to_ns(&tvblank) -
		  timeval_to_ns(&vblanktimestamp(dev, crtc, vblcount));

	/* Update vblank timestamp and count if at least
	 * DRM_REDUNDANT_VBLIRQ_THRESH_NS nanoseconds
	 * difference between last stored timestamp and current
	 * timestamp. A smaller difference means basically
	 * identical timestamps. Happens if this vblank has
	 * been already processed and this is a redundant call,
	 * e.g., due to spurious vblank interrupts. We need to
	 * ignore those for accounting.
	 */
	if (abs(diff_ns) > DRM_REDUNDANT_VBLIRQ_THRESH_NS) {
		/* Store new timestamp in ringbuffer. */
		vblanktimestamp(dev, crtc, vblcount + 1) = tvblank;
		smp_wmb();

		/* Increment cooked vblank count. This also atomically commits
		 * the timestamp computed above.
		 */
		atomic_inc(&dev->_vblank_count[crtc]);
	} else {
		DRM_DEBUG("crtc %d: Redundant vblirq ignored. diff_ns = %d\n",
			  crtc, (int) diff_ns);
	}

1310
	DRM_WAKEUP(&dev->vbl_queue[crtc]);
1311
	drm_handle_vblank_events(dev, crtc);
1312 1313

	spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
1314
	return true;
1315 1316
}
EXPORT_SYMBOL(drm_handle_vblank);