[Intel-gfx] [PATCH] drm/i915/bdw: BDW swizzling in done by the memory controller

[Chris Wilson]

On Fri, Apr 11, 2014 at 11:09:03AM +0200, Daniel Vetter wrote:
> Afaik the memory controller has always done the swizzling. What this pile
> of bits controls is the _additional_ swizzling done to improve the access
> pattern for 2d data, i.e. everything X and Y tiled. The theory of
> operation is that the additional swizzling improves access patterns when
> walking in Y direction on a surface.
> 
> And when we've last looked at this (well Chris) it seemed to indeed have
> improved sampler performace.

And recall this was around SNB time. Jesse keeps claiming that IVB+
doesn't benefit, and I'm inclined to believe him. At some point, we
should test again.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre