+/**
+ * drm_crtc_vblank_reset - reset vblank state to off on a CRTC
+ * @crtc: CRTC in question
+ *
+ * Drivers can use this function to reset the vblank state to off at load time.
+ * Drivers should use this together with the drm_crtc_vblank_off() and
+ * drm_crtc_vblank_on() functions. The difference compared to
+ * drm_crtc_vblank_off() is that this function doesn't save the vblank counter
+ * and hence doesn't need to call any driver hooks.
+ */
+void drm_crtc_vblank_reset(struct drm_crtc *drm_crtc)
+{
+ struct drm_device *dev = drm_crtc->dev;
+ unsigned long irqflags;
+ int crtc = drm_crtc_index(drm_crtc);
+ struct drm_vblank_crtc *vblank = &dev->vblank[crtc];
+
+ spin_lock_irqsave(&dev->vbl_lock, irqflags);
+ /*
+ * Prevent subsequent drm_vblank_get() from enabling the vblank
+ * interrupt by bumping the refcount.
+ */
+ if (!vblank->inmodeset) {
+ atomic_inc(&vblank->refcount);
+ vblank->inmodeset = 1;
+ }
+ spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+
+ WARN_ON(!list_empty(&dev->vblank_event_list));
+}
+EXPORT_SYMBOL(drm_crtc_vblank_reset);
+