[Intel-gfx] [PATCH] drm/i915/hsw: Implement Selective Write workaround

[Chris Wilson]

On Thu, Dec 18, 2014 at 06:20:18PM -0800, Ben Widawsky wrote:
> From: Ben Widawsky <ben at bwidawsk.net>
> 
> The docs specify this needs to be set on HSW GT1 parts. I've implemented it as
> such since it should only be needed when using RC6, but it can probably go
> anywhere.
> 
> This patch fixes extremely reproducible hangs on our Jenkins setup.
> 
> The interesting failure signature is:
>   IPEHR: 0x780c0000 (3DSTATE_VF)
>   INSTDONE_0: 0xffdfbffa (SVG + VS)

We see the same bug on IVB, and the bug (verified on hsw gt1) persists with i915.enable_rc6=0.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre