[Intel-gfx] [RFC v4 1/6] drm/i915/dp: Add a config function for YCBCR420 outputs

[Mun, Gwan-gyeong]

On Wed, 2019-03-06 at 22:52 +0200, Ville Syrjälä wrote:
> On Wed, Mar 06, 2019 at 09:30:57PM +0200, Gwan-gyeong Mun wrote:
> > This patch checks a support of YCBCR420 outputs on an encoder
> > level.
> > If the input mode is YCBCR420-only mode then it prepares DP as an
> > YCBCR420
> > output, else it continues with RGB output mode.
> > It set output_format to INTEL_OUTPUT_FORMAT_YCBCR420 in order to
> > using
> > a pipe scaler as RGB to YCbCr 4:4:4.
> > 
> > v2:
> >   Addressed review comments from Ville.
> >   Style fixed with few naming.
> >   %s/config/crtc_state/
> >   %s/intel_crtc/crtc/
> >   If lscon is active, it makes not to call
> > intel_dp_ycbcr420_config()
> >   to avoid to clobber of lspcon_ycbcr420_config() routine.
> >   And it move the 420_only check into the
> > intel_dp_ycbcr420_config().
> > 
> > v3: Fix uninitialized return value and it is reported by Dan
> > Carpenter.
> > 
> > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> > Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 39
> > ++++++++++++++++++++++++++++++++-
> >  1 file changed, 38 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index e1a051c0fbfe..882afba6e0f1 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -2104,6 +2104,38 @@ intel_dp_compute_link_config(struct
> > intel_encoder *encoder,
> >  	return 0;
> >  }
> >  
> > +static int
> > +intel_dp_ycbcr420_config(struct drm_connector *connector,
> > +			 struct intel_crtc_state *crtc_state)
> > +{
> > +	const struct drm_display_info *info = &connector->display_info;
> > +	const struct drm_display_mode *adjusted_mode =
> > +		&crtc_state->base.adjusted_mode;
> > +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
> > +	int ret;
> > +
> > +	if (drm_mode_is_420_only(info, adjusted_mode) &&
> > +	    connector->ycbcr_420_allowed) {
> 
> I would invert this into an early return. That way we avoid the
> extra indentation for the rest of the function.
> 
I agree. In order to avoid the extra indentation, I'll invert if-clause 
on intel_dp_ycbcr420_config().
> > +		crtc_state->output_format =
> > INTEL_OUTPUT_FORMAT_YCBCR420;
> > +
> > +		/* YCBCR 420 output conversion needs a scaler */
> > +		ret = skl_update_scaler_crtc(crtc_state);
> > +		if (ret) {
> > +			DRM_DEBUG_KMS("Scaler allocation for output
> > failed\n");
> > +			goto err;
> > +		}
> > +
> > +		intel_pch_panel_fitting(crtc, crtc_state,
> > +					DRM_MODE_SCALE_FULLSCREEN);
> > +	}
> > +
> > +	return 0;
> > +
> > +err:
> > +	DRM_ERROR("Can't support YCBCR420 output\n");
> 
> Remove the error print. That is user triggerable which means
> no errors prints allowed. And we already have the debug print.
> 
Thank you for your kind explanation. I'll remove the error print from
here.
> > +	return ret;
> > +}
> > +
> >  int
> >  intel_dp_compute_config(struct intel_encoder *encoder,
> >  			struct intel_crtc_state *pipe_config,
> > @@ -2120,7 +2152,7 @@ intel_dp_compute_config(struct intel_encoder
> > *encoder,
> >  		to_intel_digital_connector_state(conn_state);
> >  	bool constant_n = drm_dp_has_quirk(&intel_dp->desc,
> >  					   DP_DPCD_QUIRK_CONSTANT_N);
> > -	int ret;
> > +	int ret = 0;
> >  
> >  	if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv) && port !=
> > PORT_A)
> >  		pipe_config->has_pch_encoder = true;
> > @@ -2128,6 +2160,11 @@ intel_dp_compute_config(struct intel_encoder
> > *encoder,
> >  	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
> >  	if (lspcon->active)
> >  		lspcon_ycbcr420_config(&intel_connector->base,
> > pipe_config);
> > +	else
> > +		ret = intel_dp_ycbcr420_config(&intel_connector->base,
> > pipe_config);
> > +
> > +	if (ret)
> > +		return ret;
> >  
> >  	pipe_config->has_drrs = false;
> >  	if (IS_G4X(dev_priv) || port == PORT_A)
> > -- 
> > 2.21.0