+void drm_vblank_off(struct drm_device *dev, int crtc)
+{
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&dev->vbl_lock, irqflags);
+ dev->driver->disable_vblank(dev, crtc);
+ 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
+ * @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)
+{
+ /* vblank is not initialized (IRQ not installed ?) */
+ if (!dev->num_crtcs)
+ return;
+ /*
+ * 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]) {
+ dev->vblank_inmodeset[crtc] = 0x1;
+ if (drm_vblank_get(dev, crtc) == 0)
+ dev->vblank_inmodeset[crtc] |= 0x2;
+ }
+}
+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);
+
+ if (dev->vblank_inmodeset[crtc] & 0x2)
+ drm_vblank_put(dev, crtc);
+
+ dev->vblank_inmodeset[crtc] = 0;
+ }
+}
+EXPORT_SYMBOL(drm_vblank_post_modeset);
+