Correct vblank count value

The frame count registers don't increment until the start of the next
frame, so make sure we return an incremented count if called during the
actual vblank period.

1 files changed, 13 insertions, 2 deletions

diff --git a/shared-core/i915_irq.c b/shared-core/i915_irq.c
index bef73b62..7ad21a97 100644
--- a/shared-core/i915_irq.c
+++ b/shared-core/i915_irq.c
@@ -69,8 +69,6 @@ i915_get_pipe(struct drm_device *dev, int plane)
 static int
 i915_get_plane(struct drm_device *dev, int pipe)
 {
-	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
-
 	if (i915_get_pipe(dev, 0) == pipe)
 		return 0;
 	return 1;
@@ -349,12 +347,16 @@ 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, htotal;
 	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;
+	htotal = pipe ? HTOTAL_B : HTOTAL_A;
 
 	if (!i915_pipe_enabled(dev, pipe)) {
 	    printk(KERN_ERR "trying to get vblank count for disabled "
@@ -378,6 +380,15 @@ u32 i915_get_vblank_counter(struct drm_device *dev, int plane)
 
 	count = (high1 << 8) | low;
 
+	/*
+	 * If we're in the middle of the vblank period, the
+	 * 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(htotal) & HACTIVE_MASK)))
+		count++;
+
 	return count;
 }