4 files changed, 50 insertions, 27 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 8f28325bc5ef..1e3bdcee863c 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -333,15 +333,13 @@ static int i915_ringbuffer_info(struct seq_file *m, void *data)
 	struct drm_info_node *node = (struct drm_info_node *) m->private;
 	struct drm_device *dev = node->minor->dev;
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	unsigned int head, tail, mask;
+	unsigned int head, tail;
 
 	head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
 	tail = I915_READ(PRB0_TAIL) & TAIL_ADDR;
-	mask = dev_priv->ring.tail_mask;
 
 	seq_printf(m, "RingHead :  %08x\n", head);
 	seq_printf(m, "RingTail :  %08x\n", tail);
-	seq_printf(m, "RingMask :  %08x\n", mask);
 	seq_printf(m, "RingSize :  %08lx\n", dev_priv->ring.Size);
 	seq_printf(m, "Acthd :     %08x\n", I915_READ(IS_I965G(dev) ? ACTHD_I965 : ACTHD));
 
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 50d1f782768c..f135bdcc6d5b 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -80,6 +80,34 @@ int i915_wait_ring(struct drm_device * dev, int n, const char *caller)
 	return -EBUSY;
 }
 
+/* As a ringbuffer is only allowed to wrap between instructions, fill
+ * the tail with NOOPs.
+ */
+int i915_wrap_ring(struct drm_device *dev)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	volatile unsigned int *virt;
+	int rem;
+
+	rem = dev_priv->ring.Size - dev_priv->ring.tail;
+	if (dev_priv->ring.space < rem) {
+		int ret = i915_wait_ring(dev, rem, __func__);
+		if (ret)
+			return ret;
+	}
+	dev_priv->ring.space -= rem;
+
+	virt = (unsigned int *)
+		(dev_priv->ring.virtual_start + dev_priv->ring.tail);
+	rem /= 4;
+	while (rem--)
+		*virt++ = MI_NOOP;
+
+	dev_priv->ring.tail = 0;
+
+	return 0;
+}
+
 /**
  * Sets up the hardware status page for devices that need a physical address
  * in the register.
@@ -200,7 +228,6 @@ static int i915_initialize(struct drm_device * dev, drm_i915_init_t * init)
 		}
 
 		dev_priv->ring.Size = init->ring_size;
-		dev_priv->ring.tail_mask = dev_priv->ring.Size - 1;
 
 		dev_priv->ring.map.offset = init->ring_start;
 		dev_priv->ring.map.size = init->ring_size;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 76914ae65c31..2d5bce643e6a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -85,7 +85,6 @@ struct drm_i915_gem_phys_object {
 };
 
 typedef struct _drm_i915_ring_buffer {
-	int tail_mask;
 	unsigned long Size;
 	u8 *virtual_start;
 	int head;
@@ -790,33 +789,32 @@ extern void intel_modeset_cleanup(struct drm_device *dev);
 
 #define I915_VERBOSE 0
 
-#define RING_LOCALS	unsigned int outring, ringmask, outcount; \
-                        volatile char *virt;
-
-#define BEGIN_LP_RING(n) do {				\
-	if (I915_VERBOSE)				\
-		DRM_DEBUG("BEGIN_LP_RING(%d)\n", (n));	\
-	if (dev_priv->ring.space < (n)*4)		\
-		i915_wait_ring(dev, (n)*4, __func__);		\
-	outcount = 0;					\
-	outring = dev_priv->ring.tail;			\
-	ringmask = dev_priv->ring.tail_mask;		\
-	virt = dev_priv->ring.virtual_start;		\
+#define RING_LOCALS	volatile unsigned int *ring_virt__;
+
+#define BEGIN_LP_RING(n) do {						\
+	int bytes__ = 4*(n);						\
+	if (I915_VERBOSE) DRM_DEBUG("BEGIN_LP_RING(%d)\n", (n));	\
+	/* a wrap must occur between instructions so pad beforehand */	\
+	if (unlikely (dev_priv->ring.tail + bytes__ > dev_priv->ring.Size)) \
+		i915_wrap_ring(dev);					\
+	if (unlikely (dev_priv->ring.space < bytes__))			\
+		i915_wait_ring(dev, bytes__, __func__);			\
+	ring_virt__ = (unsigned int *)					\
+	        (dev_priv->ring.virtual_start + dev_priv->ring.tail);	\
+	dev_priv->ring.tail += bytes__;					\
+	dev_priv->ring.tail &= dev_priv->ring.Size - 1;			\
+	dev_priv->ring.space -= bytes__;				\
 } while (0)
 
-#define OUT_RING(n) do {					\
+#define OUT_RING(n) do {						\
 	if (I915_VERBOSE) DRM_DEBUG("   OUT_RING %x\n", (int)(n));	\
-	*(volatile unsigned int *)(virt + outring) = (n);	\
-        outcount++;						\
-	outring += 4;						\
-	outring &= ringmask;					\
+	*ring_virt__++ = (n);						\
 } while (0)
 
 #define ADVANCE_LP_RING() do {						\
-	if (I915_VERBOSE) DRM_DEBUG("ADVANCE_LP_RING %x\n", outring);	\
-	dev_priv->ring.tail = outring;					\
-	dev_priv->ring.space -= outcount * 4;				\
-	I915_WRITE(PRB0_TAIL, outring);			\
+	if (I915_VERBOSE)						\
+		DRM_DEBUG("ADVANCE_LP_RING %x\n", dev_priv->ring.tail);	\
+	I915_WRITE(PRB0_TAIL, dev_priv->ring.tail);			\
 } while(0)
 
 /**
@@ -839,6 +837,7 @@ extern void intel_modeset_cleanup(struct drm_device *dev);
 #define I915_GEM_HWS_INDEX		0x20
 #define I915_BREADCRUMB_INDEX		0x21
 
+extern int i915_wrap_ring(struct drm_device * dev);
 extern int i915_wait_ring(struct drm_device * dev, int n, const char *caller);
 
 #define IS_I830(dev) ((dev)->pci_device == 0x3577)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 73b58193afed..076752112a39 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4099,7 +4099,6 @@ i915_gem_init_ringbuffer(struct drm_device *dev)
 
 	/* Set up the kernel mapping for the ring. */
 	ring->Size = obj->size;
-	ring->tail_mask = obj->size - 1;
 
 	ring->map.offset = dev->agp->base + obj_priv->gtt_offset;
 	ring->map.size = obj->size;