Intel handled the management of the breadcrumb counter inconsistently.

Make sure that we always handle it the same way.

MFC after:	3 days

2 files changed, 12 insertions, 11 deletions

diff --git a/sys/dev/drm/i915_dma.c b/sys/dev/drm/i915_dma.c
index db43a88..a701a5e 100644
--- a/sys/dev/drm/i915_dma.c
+++ b/sys/dev/drm/i915_dma.c
@@ -439,8 +439,7 @@ static void i915_emit_breadcrumb(struct drm_device *dev)
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	RING_LOCALS;
 
-	dev_priv->counter++;
-	if (dev_priv->counter > 0x7FFFFFFFUL)
+	if (++dev_priv->counter > 0x7FFFFFFFUL)
 		dev_priv->counter = 0;
 	if (dev_priv->sarea_priv)
 		dev_priv->sarea_priv->last_enqueue = dev_priv->counter;
@@ -574,7 +573,10 @@ static int i915_dispatch_flip(struct drm_device * dev)
 	OUT_RING(0);
 	ADVANCE_LP_RING();
 
-	dev_priv->sarea_priv->last_enqueue = dev_priv->counter++;
+	if (++dev_priv->counter > 0x7FFFFFFFUL)
+		dev_priv->counter = 0;
+	if (dev_priv->sarea_priv)
+		dev_priv->sarea_priv->last_enqueue = dev_priv->counter;
 
 	BEGIN_LP_RING(4);
 	OUT_RING(MI_STORE_DWORD_INDEX);
diff --git a/sys/dev/drm/i915_irq.c b/sys/dev/drm/i915_irq.c
index 18400b2..7583031 100644
--- a/sys/dev/drm/i915_irq.c
+++ b/sys/dev/drm/i915_irq.c
@@ -284,14 +284,13 @@ static int i915_emit_irq(struct drm_device * dev)
 
 	i915_kernel_lost_context(dev);
 
-	DRM_DEBUG("\n");
-
-	dev_priv->counter++;
-	if (dev_priv->counter > 0x7FFFFFFFUL)
-		dev_priv->counter = 1;
+	if (++dev_priv->counter > 0x7FFFFFFFUL)
+		dev_priv->counter = 0;
 	if (dev_priv->sarea_priv)
 		dev_priv->sarea_priv->last_enqueue = dev_priv->counter;
 
+	DRM_DEBUG("emitting: %d\n", dev_priv->counter);
+
 	BEGIN_LP_RING(4);
 	OUT_RING(MI_STORE_DWORD_INDEX);
 	OUT_RING(I915_BREADCRUMB_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
@@ -331,9 +330,6 @@ static int i915_wait_irq(struct drm_device * dev, int irq_nr)
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	int ret = 0;
 
-	DRM_DEBUG("irq_nr=%d breadcrumb=%d\n", irq_nr,
-		  READ_BREADCRUMB(dev_priv));
-
 	if (READ_BREADCRUMB(dev_priv) >= irq_nr) {
 		if (dev_priv->sarea_priv) {
 			dev_priv->sarea_priv->last_dispatch =
@@ -345,6 +341,9 @@ static int i915_wait_irq(struct drm_device * dev, int irq_nr)
 	if (dev_priv->sarea_priv)
 		dev_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
 
+	DRM_DEBUG("irq_nr=%d breadcrumb=%d\n", irq_nr,
+		  READ_BREADCRUMB(dev_priv));
+
 	i915_user_irq_get(dev);
 	DRM_WAIT_ON(ret, dev_priv->irq_queue, 3 * DRM_HZ,
 		    READ_BREADCRUMB(dev_priv) >= irq_nr);