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-rw-r--r--shared-core/i915_dma.c24
-rw-r--r--shared-core/i915_drv.h10
2 files changed, 34 insertions, 0 deletions
diff --git a/shared-core/i915_dma.c b/shared-core/i915_dma.c
index fa73cd29..1fc617d1 100644
--- a/shared-core/i915_dma.c
+++ b/shared-core/i915_dma.c
@@ -69,6 +69,30 @@ int i915_wait_ring(struct drm_device * dev, int n, const char *caller)
return -EBUSY;
}
+#if I915_RING_VALIDATE
+/**
+ * Validate the cached ring tail value
+ *
+ * If the X server writes to the ring and DRM doesn't
+ * reload the head and tail pointers, it will end up writing
+ * data to the wrong place in the ring, causing havoc.
+ */
+void i915_ring_validate(struct drm_device *dev, const char *func, int line)
+{
+ drm_i915_private_t *dev_priv = dev->dev_private;
+ drm_i915_ring_buffer_t *ring = &(dev_priv->ring);
+ u32 tail = I915_READ(LP_RING+RING_TAIL) & HEAD_ADDR;
+ u32 head = I915_READ(LP_RING+RING_HEAD) & HEAD_ADDR;
+
+ if (tail != ring->tail) {
+ DRM_ERROR("%s:%d head sw %x, hw %x. tail sw %x hw %x\n",
+ func, line,
+ ring->head, head, ring->tail, tail);
+ BUG_ON(1);
+ }
+}
+#endif
+
void i915_kernel_lost_context(struct drm_device * dev)
{
drm_i915_private_t *dev_priv = dev->dev_private;
diff --git a/shared-core/i915_drv.h b/shared-core/i915_drv.h
index 029c39a0..e217b789 100644
--- a/shared-core/i915_drv.h
+++ b/shared-core/i915_drv.h
@@ -473,14 +473,23 @@ extern void intel_fini_chipset_flush_compat(struct drm_device *dev);
#define I915_WRITE16(reg,val) DRM_WRITE16(dev_priv->mmio_map, (reg), (val))
#define I915_VERBOSE 0
+#define I915_RING_VALIDATE 0
#define RING_LOCALS unsigned int outring, ringmask, outcount; \
volatile char *virt;
+#if I915_RING_VALIDATE
+void i915_ring_validate(struct drm_device *dev, const char *func, int line);
+#define I915_RING_DO_VALIDATE(dev) i915_ring_validate(dev, __FUNCTION__, __LINE__)
+#else
+#define I915_RING_DO_VALIDATE(dev)
+#endif
+
#define BEGIN_LP_RING(n) do { \
if (I915_VERBOSE) \
DRM_DEBUG("BEGIN_LP_RING(%d)\n", \
(n)); \
+ I915_RING_DO_VALIDATE(dev); \
if (dev_priv->ring.space < (n)*4) \
i915_wait_ring(dev, (n)*4, __FUNCTION__); \
outcount = 0; \
@@ -499,6 +508,7 @@ extern void intel_fini_chipset_flush_compat(struct drm_device *dev);
#define ADVANCE_LP_RING() do { \
if (I915_VERBOSE) DRM_DEBUG("ADVANCE_LP_RING %x\n", outring); \
+ I915_RING_DO_VALIDATE(dev); \
dev_priv->ring.tail = outring; \
dev_priv->ring.space -= outcount * 4; \
I915_WRITE(LP_RING + RING_TAIL, outring); \