[Intel-gfx] [PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

On Tue, Jun 21, 2016 at 03:31:25PM +0200, Daniel Vetter wrote:
> On Tue, Jun 21, 2016 at 08:25:27AM +0100, Chris Wilson wrote:
> > Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> > 
> > "Display flickering may occur when both FBC (Frame Buffer Compression)
> > and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> > and in use by the display controller."
> > 
> > Ville found the w/a name in the database:
> > WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> > 
> > v2: Log when the quirk is applied.
> > v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Do we know whether this helps on other machines too? I can imagine that
> the additional lookup latency just plain wreaks havoc everywhere ...

Yeah, they do tend to play into fifo trouble. Could find anything
though. But I think we have enough evidence to suggest acking this w/a
and moving forward if we find any others...
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre