drm: Have the vblank counter account for the time between vblank irq disable and...

If the vblank irq has already been disabled (via the disable timer) when
we call drm_vblank_off() sample the counter and timestamp one last time.
This will make the sure that the user space visible counter will account
for time between vblank irq disable and drm_vblank_off().

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index af96517..1f86f6c 100644 (file)
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -140,6 +140,19 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc)
         */
        spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
 
+       /*
+        * If the vblank interrupt was already disbled update the count
+        * and timestamp to maintain the appearance that the counter
+        * has been ticking all along until this time. This makes the
+        * count account for the entire time between drm_vblank_on() and
+        * drm_vblank_off().
+        */
+       if (!dev->vblank[crtc].enabled) {
+               drm_update_vblank_count(dev, crtc);
+               spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
+               return;
+       }
+
        dev->driver->disable_vblank(dev, crtc);
        dev->vblank[crtc].enabled = false;