diff --git a/linux-core/drm_irq.c b/linux-core/drm_irq.c
index 2a5a453..7001c06 100644
--- a/linux-core/drm_irq.c
+++ b/linux-core/drm_irq.c
@@ -332,6 +332,8 @@ void drm_update_vblank_count(struct drm_device *dev, int crtc)
 		diff = dev->max_vblank_count -
 			dev->last_vblank[crtc];
 		diff += cur_vblank;
+		printk(KERN_ERR "vblank count wrap!\n");
+		dump_stack();
 	} else {
 		diff = cur_vblank - dev->last_vblank[crtc];
 	}
diff --git a/shared-core/i915_drv.h b/shared-core/i915_drv.h
index 7a0c0ea..c92758f 100644
--- a/shared-core/i915_drv.h
+++ b/shared-core/i915_drv.h
@@ -794,7 +794,11 @@ extern int i915_wait_ring(struct drm_device * dev, int n, const char *caller);
 #define VSYNCSHIFT_B	0x61028
 
 #define HACTIVE_MASK	0x00000fff
+#define VTOTAL_MASK	0x00001fff
+#define VTOTAL_SHIFT	16
 #define VACTIVE_MASK	0x00000fff
+#define VBLANK_END_MASK	0x00001fff
+#define VBLANK_END_SHIFT 16
 #define VBLANK_START_MASK 0x00001fff
 
 #define PP_STATUS	0x61200
diff --git a/shared-core/i915_irq.c b/shared-core/i915_irq.c
index 56bcac9..d463f6e 100644
--- a/shared-core/i915_irq.c
+++ b/shared-core/i915_irq.c
@@ -341,22 +341,39 @@ static void i915_vblank_tasklet(struct drm_device *dev)
 		drm_free(swap_hit, sizeof(*swap_hit), DRM_MEM_DRIVER);
 	}
 }
+#if 0
+static int i915_in_vblank(struct drm_device *dev, int pipe)
+{
+	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+	unsigned long pipedsl, vblank, vtotal;
+	unsigned long vbl_start, vbl_end, cur_line;
+
+	pipedsl = pipe ? PIPEBDSL : PIPEADSL;
+	vblank = pipe ? VBLANK_B : VBLANK_A;
+	vtotal = pipe ? VTOTAL_B : VTOTAL_A;
+
+	vbl_start = I915_READ(vblank) & VBLANK_START_MASK;
+	vbl_end = (I915_READ(vblank) >> VBLANK_END_SHIFT) & VBLANK_END_MASK;
+
+	cur_line = I915_READ(pipedsl);
+
+	if (cur_line >= vbl_start)
+		return 1;
 
+	return 0;
+}
+#endif
 u32 i915_get_vblank_counter(struct drm_device *dev, int plane)
 {
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	unsigned long high_frame;
 	unsigned long low_frame;
-	unsigned long pipedsl, vblank, vtotal;
 	u32 high1, high2, low, count;
 	int pipe;
 
 	pipe = i915_get_pipe(dev, plane);
 	high_frame = pipe ? PIPEBFRAMEHIGH : PIPEAFRAMEHIGH;
 	low_frame = pipe ? PIPEBFRAMEPIXEL : PIPEAFRAMEPIXEL;
-	pipedsl = pipe ? PIPEBDSL : PIPEADSL;
-	vblank = pipe ? VBLANK_B : VBLANK_A;
-	vtotal = pipe ? VTOTAL_B : VTOTAL_A;
 
 	if (!i915_pipe_enabled(dev, pipe)) {
 	    printk(KERN_ERR "trying to get vblank count for disabled "
@@ -385,10 +402,10 @@ u32 i915_get_vblank_counter(struct drm_device *dev, int plane)
 	 * above regs won't have been updated yet, so return
 	 * an incremented count to stay accurate
 	 */
-	if ((I915_READ(pipedsl) >= (I915_READ(vblank) & VBLANK_START_MASK)) ||
-	    (I915_READ(pipedsl) < (I915_READ(vtotal) & VACTIVE_MASK)))
+#if 0
+	if (i915_in_vblank(dev, pipe))
 		count++;
-
+#endif
 	return count;
 }