drm/i915/dp: Enable AUX based backlight for HDR

[Ville Syrjälä]

On Fri, Mar 15, 2024 at 12:33:52PM +0100, Sebastian Wick wrote:
> On Fri, Mar 15, 2024 at 10:35:30AM +0530, Suraj Kandpal wrote:
<snip>
> > @@ -318,11 +346,24 @@ intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pi
> >  		panel->backlight.min = 0;
> >  	}
> >  
> > +	if (DISPLAY_VER(i915) < 11) {
> 
> This should check for INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP instead!
> There is no reason to bind this to any hardware version if the hardware
> itself can tell you if it supports SDP signalling or needs to set it via
> AUX.

That should be OK for icl+.

To extend this to pre-icl hardware I think we pretty much need both checks:
- has_gamut_metadata_dip() -> can we actually transmit the SDP?
- INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP -> can the tcon extract the data from the SDP?
and if either is false then we fall back to AUX.

We should also change intel_dp_add_properties() to check
the tcon caps instead of relying on has_gamut_metadata_dip(),
	for eDP.

-- 
Ville Syrjälä
Intel