Re: [PATCH 21/23] drm/i915/gen9: Set fbc watermarks disabled

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 26, 2016 at 06:53:18PM +0300, Ville Syrjälä wrote:
> On Thu, May 26, 2016 at 06:29:44PM +0300, Mika Kuoppala wrote:
> > According to bspec this prevents screen corruption when fbc is
> > used.
> > 
> > References: HSD#2135555, HSD#2137270
> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 262180c0ba70..62734a16e873 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -67,6 +67,9 @@ static void gen9_init_clock_gating(struct drm_device *dev)
> >  
> >  	I915_WRITE(GEN8_CHICKEN_DCPR_1,
> >  		   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
> > +
> > +	I915_WRITE(DISP_ARB_CTL,
> > +		   I915_READ(DISP_ARB_CTL) | DISP_FBC_WM_DIS);
> 
> Hmm I thought that FBC WM doesn't exist anymore on SKL+. I'm pretty sure
> we don't have any code for it at least.

Hmm. I guess the bit still does something though.

Do we want to start using the bspec w/a IDs in comments?

Hmm. w/a db seems to have a name for this FBC stuff as well. This one
looks like
WaFbcTurnOffFbcWatermark

> 
> >  }
> >  
> >  static void bxt_init_clock_gating(struct drm_device *dev)
> > @@ -2798,7 +2801,7 @@ static void ilk_write_wm_values(struct drm_i915_private *dev_priv,
> >  
> >  	if (dirty & WM_DIRTY_FBC) {
> >  		val = I915_READ(DISP_ARB_CTL);
> > -		if (results->enable_fbc_wm)
> > +		if (!IS_GEN9(dev) && results->enable_fbc_wm)
> 
> That code won't even run SKL+.
> 
> >  			val &= ~DISP_FBC_WM_DIS;
> >  		else
> >  			val |= DISP_FBC_WM_DIS;
> > -- 
> > 2.5.0
> > 
> > _______________________________________________
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> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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