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;