[Intel-gfx] [PATCH] drm/i915/color: fix broken display in icl+

[Saarinen, Jani]

HI, 

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Ville Syrjälä
> Sent: tiistai 1. lokakuuta 2019 17.21
> To: Nikula, Jani <jani.nikula at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>
> Subject: Re: [Intel-gfx] [PATCH] drm/i915/color: fix broken display in icl+
> 
> On Tue, Oct 01, 2019 at 11:03:08AM +0300, Jani Nikula wrote:
> > On Tue, 01 Oct 2019, Swati Sharma <swati2.sharma at intel.com> wrote:
> > > Premature gamma lut prepration and loading which was getting
> > > reflected in first modeset causing different colors on screen during
> > > boot.
> > >
> > > Issue: In BIOS, gamma is disabled by default. However,
> > > legacy_read_luts() was getting called even before the
> > > legacy_load_luts() which was setting crtc_state->base.gamma_lut and
> > > gamma_lut was programmed with junk values which led to visual
> > > artifacts (different colored screens instead of usual black during boot).
> > >
> > > Fix: Calling read_luts() only when gamma is enabled which will
> > > happen after first modeset.
> > >
> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111809
> >
> > I'm confused. Is there a current problem upstream after the revert
> > 1b8588741fdc ("Revert "drm/i915/color: Extract icl_read_luts()"")?
> >
> > Or does this fix a problem that only occurs in conjunction with the
> > reverted commit? Then say so.
> >
> > Note inline.
> >
> > > Signed-off-by: Swati Sharma <swati2.sharma at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > > b/drivers/gpu/drm/i915/display/intel_display.c
> > > index f1328c08f4ad..f89aa4bb9f42 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > @@ -10528,7 +10528,9 @@ static bool haswell_get_pipe_config(struct
> intel_crtc *crtc,
> > >  		i9xx_get_pipe_color_config(pipe_config);
> > >  	}
> > >
> > > -	intel_color_get_config(pipe_config);
> > > +	if ((INTEL_GEN(dev_priv) >= 11 && (pipe_config->gamma_mode &
> POST_CSC_GAMMA_ENABLE)) ||
> > > +	   (INTEL_GEN(dev_priv) >= 9 && (pipe_config->gamma_enable)))
> > > +			intel_color_get_config(pipe_config);
> >
> > Put all of the conditions inside intel_color_get_config().
> 
> In fact inside the .read_luts() since these checks are platform specific.
> 
> Also this check is wrong for CHV since it has a separate enable knob for the CGM LUT
> (gamma_enable only deals with the legacy LUT).
Could this be also reason that on BSW I was able to see some color issue with BSW on latest drm-tip still with Tapani? 

> 
> --
> Ville Syrjälä
> Intel
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