On Wed, Nov 28, 2012 at 09:45:46PM +0100, Daniel Vetter wrote: > On Tue, Nov 27, 2012 at 08:34:55PM +0200, ville.syrjala at linux.intel.com wrote: > > From: Ville Syrj?l? <ville.syrjala at 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 > > > > Signed-off-by: Ville Syrj?l? <ville.syrjala at linux.intel.com> > > Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk> > > Another small bikeshed for this one: Less magic numbers with > > #define RING_FREE_SPACE 64 Can do. And since the number will only appear in one place, I think I'll stick the BSpec references into a comment above it. -- Ville Syrj?l? Intel OTC
