Re: [PATCH 14/15] drm/i915: skl nv12 workarounds

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

On Wed, Sep 09, 2015 at 02:51:58AM +0300, Konduru, Chandra wrote:
> > > > > +static void skl_wa_clkgate(struct drm_i915_private *dev_priv,
> > > > > +	int pipe, int enable)
> > > > > +{
> > > > > +	if (pipe == PIPE_A || pipe == PIPE_B) {
> > > > > +		if (enable)
> > > > > +			I915_WRITE(CLKGATE_DIS_PSL(pipe),
> > > > > +				DUPS1_GATING_DIS | DUPS2_GATING_DIS);
> > > > > +		else
> > > > > +			I915_WRITE(CLKGATE_DIS_PSL(pipe),
> > > > > +				I915_READ(CLKGATE_DIS_PSL(pipe) &
> > > > > +				~(DUPS1_GATING_DIS|DUPS2_GATING_DIS)));
> > > > > +	}
> > > > > +}
> > > > > +
> > > > >  static void haswell_crtc_enable(struct drm_crtc *crtc)
> > > > >  {
> > > > >  	struct drm_device *dev = crtc->dev;
> > > > > @@ -5094,6 +5119,9 @@ static void haswell_crtc_enable(struct drm_crtc
> > > > *crtc)
> > > > >  		intel_wait_for_vblank(dev, hsw_workaround_pipe);
> > > > >  		intel_wait_for_vblank(dev, hsw_workaround_pipe);
> > > > >  	}
> > > > > +
> > > > > +	/* workaround for NV12 */
> > > > > +	skl_wa_clkgate(dev_priv, pipe, 1);
> > > >
> > > > I wonder what's the cost of having this
> > > > a) always enabled
> > > > b) enabled when the pipe is enabled
> > > > c) enabled only when NV12 is used
> > > > ?
> > >
> > > Initially optimized to enable only when nv12 is used,
> > > but there are some corner cases when planes switch to and
> > > from nv12 to non-nv12 and SV recommendation is to enable
> > > always; and SV evaluated cost, and it isn't a big concern.
> > 
> > So, based on that we could just stuff it into init_clock_gating and
> > forget about it.
> 
> Couldn't include into init_clock_gating because this requires
> a pipe based check.

init_clock_gating()
{
	...
	enable for pipe A
	enable for pipe B
	...
}

or

for_each_pipe(pipe)
	if (pipe != C)
		enable w/a


> 
> By the way, so far 4 patches got RB tags.
> In the respun series (http://lists.freedesktop.org/archives/intel-gfx/2015-September/075235.html
> addressed your feedback), those 4 tags goes to 1, 3, 5 and 8 of 15.
> Can you check updated patches and issue R-B tags for remaining ones?

I think your trigger finger is a bit overly sensitive :) We still had
open issues in this series so posting another one makes things somewhat
messy.

-- 
Ville Syrjälä
Intel OTC
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