| Message ID | 1354553012-31964-1-git-send-email-ville.syrjala@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Dec 03, 2012 at 06:43:32PM +0200, ville.syrjala@linux.intel.com wrote: > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > From BSpec: > "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." > > The easiest way to enforce this is to reduce the reported ring space. > > References: > 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" > > v2: Include the exact BSpec references in the description > > v3: s/64/I915_RING_FREE_SPACE, and add the BSpec information to the code > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Picked up for -fixes, thanks for the patch. -Daniel
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index 2635ee6..a333d1d 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -141,7 +141,7 @@ void i915_kernel_lost_context(struct drm_device * dev) ring->head = I915_READ_HEAD(ring) & HEAD_ADDR; ring->tail = I915_READ_TAIL(ring) & TAIL_ADDR; - ring->space = ring->head - (ring->tail + 8); + ring->space = ring->head - (ring->tail + I915_RING_FREE_SPACE); if (ring->space < 0) ring->space += ring->size; diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 36e1e13a..402a0d7 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -45,7 +45,7 @@ struct pipe_control { static inline int ring_space(struct intel_ring_buffer *ring) { - int space = (ring->head & HEAD_ADDR) - (ring->tail + 8); + int space = (ring->head & HEAD_ADDR) - (ring->tail + I915_RING_FREE_SPACE); if (space < 0) space += ring->size; return space; @@ -1231,7 +1231,7 @@ static int intel_ring_wait_request(struct intel_ring_buffer *ring, int n) if (request->tail == -1) continue; - space = request->tail - (ring->tail + 8); + space = request->tail - (ring->tail + I915_RING_FREE_SPACE); if (space < 0) space += ring->size; if (space >= n) { diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index d4b7416..526182e 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -1,6 +1,17 @@ #ifndef _INTEL_RINGBUFFER_H_ #define _INTEL_RINGBUFFER_H_ +/* + * 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 { u32 *page_addr; unsigned int gfx_addr;