@@ -303,6 +303,32 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
store_vblank(dev, pipe, diff, &t_vblank, cur_vblank);
}
+/**
+ * drm_accurate_vblank_count - retrieve the master vblank counter
+ * @crtc: which counter to retrieve
+ *
+ * This function is similar to @drm_crtc_vblank_count but this
+ * function interpolates to handle a race with vblank irq's.
+ */
+
+u32 drm_accurate_vblank_count(struct drm_crtc *crtc)
+{
+ struct drm_device *dev = crtc->dev;
+ unsigned int pipe = drm_crtc_index(crtc);
+ u32 vblank;
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->vblank_time_lock, flags);
+
+ drm_update_vblank_count(dev, pipe, 0);
+ vblank = dev->vblank[pipe].count;
+
+ spin_unlock_irqrestore(&dev->vblank_time_lock, flags);
+
+ return vblank;
+}
+EXPORT_SYMBOL(drm_accurate_vblank_count);
+
/*
* Disable vblank irq's on crtc, make sure that last vblank count
* of hardware and corresponding consistent software vblank counter
@@ -995,6 +995,7 @@ extern void drm_crtc_vblank_off(struct drm_crtc *crtc);
extern void drm_crtc_vblank_reset(struct drm_crtc *crtc);
extern void drm_crtc_vblank_on(struct drm_crtc *crtc);
extern void drm_vblank_cleanup(struct drm_device *dev);
+extern u32 drm_accurate_vblank_count(struct drm_crtc *crtc);
extern u32 drm_vblank_no_hw_counter(struct drm_device *dev, unsigned int pipe);
extern int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,