1 files changed, 26 insertions, 8 deletions

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 6b3ce6d38848..7998ee66b317 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -429,15 +429,21 @@ int drm_vblank_get(struct drm_device *dev, int crtc)
 
         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)
+        if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) {
+                if (!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);
+                        }
+                }
+        } else {
+                if (!dev->vblank_enabled[crtc]) {
                         atomic_dec(&dev->vblank_refcount[crtc]);
-                else {
-                        dev->vblank_enabled[crtc] = 1;
-                        drm_update_vblank_count(dev, crtc);
+                        ret = -EINVAL;
                 }
         }
         spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
@@ -464,6 +470,18 @@ void drm_vblank_put(struct drm_device *dev, int crtc)
 }
 EXPORT_SYMBOL(drm_vblank_put);
 
+void drm_vblank_off(struct drm_device *dev, int crtc)
+{
+        unsigned long irqflags;
+
+        spin_lock_irqsave(&dev->vbl_lock, irqflags);
+        DRM_WAKEUP(&dev->vbl_queue[crtc]);
+        dev->vblank_enabled[crtc] = 0;
+        dev->last_vblank[crtc] = dev->driver->get_vblank_counter(dev, crtc);
+        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+}
+EXPORT_SYMBOL(drm_vblank_off);
+
 /**
  * drm_vblank_pre_modeset - account for vblanks across mode sets
  * @dev: DRM device