diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_ringbuffer.h')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ringbuffer.h | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index 600713b29d79..650ab884d6c8 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -17,17 +17,6 @@ #define CACHELINE_BYTES 64 #define CACHELINE_DWORDS (CACHELINE_BYTES / sizeof(uint32_t)) -/* - * Gen2 BSpec "1. Programming Environment" / 1.4.4.6 "Ring Buffer Use" - * Gen3 BSpec "vol1c Memory Interface Functions" / 2.3.4.5 "Ring Buffer Use" - * Gen4+ BSpec "vol1c Memory Interface and Command Stream" / 5.3.4.5 "Ring Buffer Use" - * - * "If the Ring Buffer Head Pointer and the Tail Pointer are on the same - * cacheline, the Head Pointer must not be greater than the Tail - * Pointer." - */ -#define I915_RING_FREE_SPACE 64 - struct intel_hw_status_page { struct i915_vma *vma; u32 *page_addr; @@ -145,9 +134,9 @@ struct intel_ring { u32 tail; u32 emit; - int space; - int size; - int effective_size; + u32 space; + u32 size; + u32 effective_size; }; struct i915_gem_context; @@ -548,6 +537,25 @@ assert_ring_tail_valid(const struct intel_ring *ring, unsigned int tail) */ GEM_BUG_ON(!IS_ALIGNED(tail, 8)); GEM_BUG_ON(tail >= ring->size); + + /* + * "Ring Buffer Use" + * Gen2 BSpec "1. Programming Environment" / 1.4.4.6 + * Gen3 BSpec "1c Memory Interface Functions" / 2.3.4.5 + * Gen4+ BSpec "1c Memory Interface and Command Stream" / 5.3.4.5 + * "If the Ring Buffer Head Pointer and the Tail Pointer are on the + * same cacheline, the Head Pointer must not be greater than the Tail + * Pointer." + * + * We use ring->head as the last known location of the actual RING_HEAD, + * it may have advanced but in the worst case it is equally the same + * as ring->head and so we should never program RING_TAIL to advance + * into the same cacheline as ring->head. + */ +#define cacheline(a) round_down(a, CACHELINE_BYTES) + GEM_BUG_ON(cacheline(tail) == cacheline(ring->head) && + tail < ring->head); +#undef cacheline } static inline unsigned int |
