On Wed, Sep 26, 2018 at 03:56:39PM +0300, Mika Kuoppala wrote:
> Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> writes:
>
> > On Tue, Sep 25, 2018 at 04:38:03PM +0300, Mika Kuoppala wrote:
> >> Using fbc with VT-d flickers also on kbl and cfl.
> >>
> >> Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> >> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> >> Cc: <stable@xxxxxxxxxxxxxxx> # v4.9+
> >> Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> >> ---
> >> drivers/gpu/drm/i915/intel_fbc.c | 5 +++--
> >> 1 file changed, 3 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> >> index 74d425c700ef..a149f08c1b79 100644
> >> --- a/drivers/gpu/drm/i915/intel_fbc.c
> >> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> >> @@ -1275,9 +1275,10 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
> >>
> >> static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv)
> >> {
> >> - /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> >> + /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt,kbl,cfl */
> >
> > The hsds seem to be saying that this was fixed in kbl/cnl. I guess the
> > flicker could be due to a different vt-d vs. fbc issue.
> >
>
> I was trusting the wa database on this one.
I believe it would be worth to trust the wa_database,
but this database can be tricky too...
Like on this case it is listed for KBL, but A0 only
and not listed for CFL.
>
> > Is the chicken bit in CHICKEN_PIPESL in the correct position?
>
> Yes it is zero.
>
> >
> > Hmm. Bspec doesn't list chicken bit for glk. That would seem to suggest
> > that we need this w/a for glk as well.
>
> Agreed. The questio is that should we follow bspec and logic or
> leave it until we get a report if it is a problem?
>
> cfl is close enough|similar in this respect that we mimic
> kbl with it?
yes, we can safely consider it is similar to latest steppings of KBL.
>
> Thanks,
> -Mika
>
> >
> >> if (intel_vtd_active() &&
> >> - (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv))) {
> >> + (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv) ||
> >> + IS_KABYLAKE(dev_priv) || IS_COFFEELAKE(dev_priv))) {
> >> DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> >> return true;
> >> }
> >> --
> >> 2.17.1
> >
> > --
> > Ville Syrjälä
> > Intel
