On Thu, Aug 04, 2016 at 09:31:20AM +0300, Jani Nikula wrote:
> On Wed, 03 Aug 2016, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> 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()
> > v4: Fix function name after rebase
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Cc: stable@xxxxxxxxxxxxxxx
fbc isn't enabled by default, so imo no.
-Daniel
>
> ?
>
> > ---
> > drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
> > 1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> > index 8147eb9e8475..b673c7c54a46 100644
> > --- a/drivers/gpu/drm/i915/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/intel_fbc.c
> > @@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
> > if (i915.enable_fbc >= 0)
> > return !!i915.enable_fbc;
> >
> > + if (!HAS_FBC(dev_priv))
> > + return 0;
> > +
> > if (IS_BROADWELL(dev_priv))
> > return 1;
> >
> > return 0;
> > }
> >
> > +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> > +{
> > +#ifdef CONFIG_INTEL_IOMMU
> > + /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> > + if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
> > + DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> > + return true;
> > + }
> > +#endif
> > +
> > + return false;
> > +}
> > +
> > /**
> > * intel_fbc_init - Initialize FBC
> > * @dev_priv: the i915 device
> > @@ -1252,6 +1268,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
> > fbc->active = false;
> > fbc->work.scheduled = false;
> >
> > + if (need_fbc_wa(dev_priv))
> > + mkwrite_device_info(dev_priv)->has_fbc = false;
> > +
> > i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
> > DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
>
> --
> Jani Nikula, Intel Open Source Technology Center
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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