Re: [PATCH 10/14] drm/i915/display/vdsc: Add ultrajoiner support with DSC

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

On Fri, Sep 06, 2024 at 07:30:16PM +0300, Ville Syrjälä wrote:
> On Fri, Sep 06, 2024 at 06:28:03PM +0530, Ankit Nautiyal wrote:
> > From: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > 
> > Add changes to DSC which are required for Ultrajoiner.
> > 
> > v2:
> > -Use correct helper for setting bits for bigjoiner secondary. (Ankit)
> > -Use enum for joiner pipe count instead magic numbers. (Suraj)
> > -Use primary/secondary instead of master/slave. (Suraj)
> > 
> > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_vdsc.c | 26 +++++++++++++++++++++--
> >  1 file changed, 24 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
> > index 8158e3702ed5..66e810c8de68 100644
> > --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
> > @@ -379,9 +379,11 @@ static int intel_dsc_get_vdsc_per_pipe(const struct intel_crtc_state *crtc_state
> >  int intel_dsc_get_num_vdsc_instances(const struct intel_crtc_state *crtc_state)
> >  {
> >  	int num_vdsc_instances = intel_dsc_get_vdsc_per_pipe(crtc_state);
> > +	int joined_pipes = intel_joiner_num_pipes(crtc_state);
> >  
> > -	if (crtc_state->joiner_pipes)
> > -		num_vdsc_instances *= 2;
> > +	if (joined_pipes == INTEL_BIG_JOINER_PIPES ||
> > +	    joined_pipes == INTEL_ULTRA_JOINER_PIPES)
> > +		num_vdsc_instances *= joined_pipes;
> >  
> >  	return num_vdsc_instances;
> >  }
> > @@ -751,6 +753,14 @@ void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state)
> >  	}
> >  }
> >  
> > +static bool intel_crtc_ultrajoiner_enable_needed(const struct intel_crtc_state *crtc_state)
> > +{
> > +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > +
> > +	return intel_joiner_num_pipes(crtc_state) == INTEL_ULTRA_JOINER_PIPES &&
> > +	       crtc->pipe != PIPE_D;
> > +}
> > +
> >  void intel_dsc_enable(const struct intel_crtc_state *crtc_state)
> >  {
> >  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > @@ -770,7 +780,19 @@ void intel_dsc_enable(const struct intel_crtc_state *crtc_state)
> >  		dss_ctl1_val |= JOINER_ENABLE;
> >  	}
> >  	if (crtc_state->joiner_pipes) {
> > +		/*
> > +		 * This bit doesn't seem to follow primary/secondary logic or
> > +		 * any other logic, so lets just add helper function to
> > +		 * at least hide this hassle..
> > +		 */
> > +		if (intel_crtc_ultrajoiner_enable_needed(crtc_state))
> 
> What is this crazyness? This would throw a big wrench into
> the works, eg. the ultrajoiner readout would not work as intended.

Hmm. I do see a note to this effect in bspec. But that doesn't make
any real sense. I would expect that we either enable this for
everything, or only for pipes A+C (the bigjoiner primaries).
The latter would seem sensible, but it would also mean that
we need to rethink the readout as well.

> 
> > +			dss_ctl1_val |= ULTRA_JOINER_ENABLE;
> > +
> > +		if (intel_crtc_is_ultrajoiner_primary(crtc_state))
> > +			dss_ctl1_val |= PRIMARY_ULTRA_JOINER_ENABLE;
> > +
> >  		dss_ctl1_val |= BIG_JOINER_ENABLE;
> > +
> >  		if (intel_crtc_is_bigjoiner_primary(crtc_state))
> >  			dss_ctl1_val |= PRIMARY_BIG_JOINER_ENABLE;
> >  	}
> > -- 
> > 2.45.2
> 
> -- 
> Ville Syrjälä
> Intel

-- 
Ville Syrjälä
Intel