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Commit e6ae8687 authored by Rob Clark's avatar Rob Clark Committed by Daniel Vetter
Browse files

drm: idiot-proof vblank 



After spending slightly more time than I'd care to admit debugging the
various and presumably spectacular way things fail when you pass too low
a value to drm_vblank_init() (thanks console-lock for not letting me see
the carnage!), I decided it might be a good idea to add some sanity
checking.

Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent ddde4371

drivers/gpu/drm/drm_irq.c

+24 −0
Original line number Diff line number Diff line
@@ -730,6 +730,8 @@ EXPORT_SYMBOL(drm_get_last_vbltimestamp); 
 */

u32 drm_vblank_count(struct drm_device *dev, int crtc)

{

	if (WARN_ON(crtc >= dev->num_crtcs))

		return 0;

	return atomic_read(&dev->vblank[crtc].count);

}

EXPORT_SYMBOL(drm_vblank_count);
@@ -752,6 +754,9 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, int crtc, 
{

	u32 cur_vblank;



	if (WARN_ON(crtc >= dev->num_crtcs))

		return 0;



	/* Read timestamp from slot of _vblank_time ringbuffer

	 * that corresponds to current vblank count. Retry if

	 * count has incremented during readout. This works like
@@ -927,6 +932,9 @@ int drm_vblank_get(struct drm_device *dev, int crtc) 
	unsigned long irqflags;

	int ret = 0;



	if (WARN_ON(crtc >= dev->num_crtcs))

		return -EINVAL;



	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[crtc].refcount) == 1) {
@@ -975,6 +983,9 @@ void drm_vblank_put(struct drm_device *dev, int crtc) 
{

	BUG_ON(atomic_read(&dev->vblank[crtc].refcount) == 0);



	if (WARN_ON(crtc >= dev->num_crtcs))

		return;



	/* Last user schedules interrupt disable */

	if (atomic_dec_and_test(&dev->vblank[crtc].refcount) &&

	    (drm_vblank_offdelay > 0))
@@ -1019,6 +1030,9 @@ void drm_vblank_off(struct drm_device *dev, int crtc) 
	unsigned long irqflags;

	unsigned int seq;



	if (WARN_ON(crtc >= dev->num_crtcs))

		return;



	spin_lock_irqsave(&dev->vbl_lock, irqflags);

	vblank_disable_and_save(dev, crtc);

	wake_up(&dev->vblank[crtc].queue);
@@ -1078,6 +1092,9 @@ void drm_vblank_on(struct drm_device *dev, int crtc) 
{

	unsigned long irqflags;



	if (WARN_ON(crtc >= dev->num_crtcs))

		return;



	spin_lock_irqsave(&dev->vbl_lock, irqflags);

	/* re-enable interrupts if there's are users left */

	if (atomic_read(&dev->vblank[crtc].refcount) != 0)
@@ -1131,6 +1148,10 @@ void drm_vblank_pre_modeset(struct drm_device *dev, int crtc) 
	/* vblank is not initialized (IRQ not installed ?), or has been freed */

	if (!dev->num_crtcs)

		return;



	if (WARN_ON(crtc >= dev->num_crtcs))

		return;



	/*

	 * To avoid all the problems that might happen if interrupts

	 * were enabled/disabled around or between these calls, we just
@@ -1439,6 +1460,9 @@ bool drm_handle_vblank(struct drm_device *dev, int crtc) 
	if (!dev->num_crtcs)

		return false;



	if (WARN_ON(crtc >= dev->num_crtcs))

		return false;



	/* Need timestamp lock to prevent concurrent execution with

	 * vblank enable/disable, as this would cause inconsistent

	 * or corrupted timestamps and vblank counts.