diff options
Diffstat (limited to 'shared-core/i915_dma.c')
| -rw-r--r-- | shared-core/i915_dma.c | 24 |
1 files changed, 24 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; |