[Intel-gfx] [PATCH 17/30] drm/i915: Do not clflush snooped objects

[Chris Wilson]

On Wed, 13 Apr 2011 18:04:38 +0200, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Tue, Apr 12, 2011 at 09:31:45PM +0100, Chris Wilson wrote:
> > +	/* If the GPU is snooping the contents of the CPU cache,
> > +	 * we do not need to clear the CPU cache lines. Instead we need
> > +	 * to be sure to flush/invalidate the RENDER cache when the contents
> > +	 * must be refreshed.
> > +	 */
> 
> The "Instead we need to be sure to flush the RENDER cache ..." is a bit
> confusing to me: There's no instead, we have to do this always when
> writing with the cpu. Besides this minor comment-nitpick it makes sense.

I changed the comment to:

/* If the GPU is snooping the contents of the CPU cache,
 * we do not need to manually clear the CPU cache lines.  Instead,
 * the caches are only snooped when the render cache is
 * flushed/invalidated.  As we always have to emit invalidations
 * and flushes when moving into and out of the RENDER domain, correct
 * snooping behaviour occurs naturally as the result of our domain
 * tracking.
 */
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre