Re: [PATCH 5/5] drm/edid: Set YQ bits in the AVI infoframe according to CEA-861-F

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

On Thu, Jan 12, 2017 at 12:13:47PM +0200, Jani Nikula wrote:
> On Wed, 11 Jan 2017, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > CEA-861-F tells us:
> > "When transmitting any RGB colorimetry, the Source should set the
> >  YQ-field to match the RGB Quantization Range being transmitted
> >  (e.g., when Limited Range RGB, set YQ=0 or when Full Range RGB,
> >  set YQ=1) and the Sink shall ignore the YQ-field."
> >
> > So let's go ahead and do that. Perhaps there are sinks that don't
> > ignore the YQ as they should for RGB?
> >
> > I wasn't able to find similar text in CEA-861-E, so it would seem
> > to be a fairly "recent" addition.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/drm_edid.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index caa2435bac31..6ba9a1a6eae4 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -4320,6 +4320,20 @@ drm_hdmi_avi_infoframe_quant_range(struct hdmi_avi_infoframe *frame,
> >  		frame->quantization_range = rgb_quant_range;
> >  	else
> >  		frame->quantization_range = HDMI_QUANTIZATION_RANGE_DEFAULT;
> > +
> > +	/*
> > +	 * CEA-861-F:
> > +	 * "When transmitting any RGB colorimetry, the Source should set the
> > +	 *  YQ-field to match the RGB Quantization Range being transmitted
> > +	 *  (e.g., when Limited Range RGB, set YQ=0 or when Full Range RGB,
> > +	 *  set YQ=1) and the Sink shall ignore the YQ-field."
> > +	 */
> 
> *rolls eyes* but that's what the spec says.
> 
> > +	if (rgb_quant_range == HDMI_QUANTIZATION_RANGE_LIMITED)
> > +		frame->ycc_quantization_range =
> > +			HDMI_YCC_QUANTIZATION_RANGE_LIMITED;
> > +	else
> > +		frame->ycc_quantization_range =
> > +			HDMI_YCC_QUANTIZATION_RANGE_FULL;
> 
> Shouldn't this take into account QS=0 and rgb_quant_range != default?

There is no YQ setting similar to the default Q=0. YQ=0 means "limited",
YQ=1 means "full", others values are reserved. So we can't really not
specify the YCC quantization range. So I can't really see any better
option than telling the truth.

-- 
Ville Syrjälä
Intel OTC
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