[Intel-gfx] [PATCH v3 2/2] drm/i915/bxt: don't allow cached GEM mappings on A stepping

[Daniel Vetter]

On Fri, Aug 14, 2015 at 05:18:27PM +0100, Chris Wilson wrote:
> On Fri, Aug 14, 2015 at 06:43:30PM +0300, Imre Deak wrote:
> > Due to a coherency issue on BXT A steppings we can't guarantee a
> > coherent view of cached (CPU snooped) GPU mappings, so fail such
> > requests. User space is supposed to fall back to uncached mappings in
> > this case.
> > 
> > v2:
> > - limit the WA to A steppings, on later stepping this HW issue is fixed
> > v3:
> > - return error instead of trying to work around the issue in kernel,
> >   since that could confuse user space (Chris)
> > 
> > Testcast: igt/gem_store_dword_batches_loop/cached-mapping
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> 
> I checked in the two userspaces where I have used snooping that both
> handle an error correctly, so
> 
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Both patches applied, thanks.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch