[Intel-gfx] [PATCH v2 12/12] drm/i915/dp: Disable DFP RGB->YCbCr conversion for now

[Shankar, Uma]

> -----Original Message-----
> From: Ville Syrjala <ville.syrjala at linux.intel.com>
> Sent: Tuesday, March 22, 2022 5:30 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>; Shankar, Uma
> <uma.shankar at intel.com>
> Subject: [PATCH v2 12/12] drm/i915/dp: Disable DFP RGB->YCbCr conversion for
> now
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> We lack sufficient state tracking to figure out whether we want the DFP to perform
> the RGB->YCbCr conversion for us or not. So currently we are blindly just enabling
> that all the time when supported by the DFP. That is nonsense. So until we imporve
> our state tracking for this just disable the feature.
> 
> Cc: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> Cc: Uma Shankar <uma.shankar at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index d3d458b3267d..a57581198a47 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1180,6 +1180,7 @@ static bool intel_dp_supports_dsc(struct intel_dp
> *intel_dp,  static bool intel_dp_is_ycbcr420(struct intel_dp *intel_dp,
>  				 const struct intel_crtc_state *crtc_state)  {
> +	/* FIXME see intel_dp_update_420() regarding rgb_to_ycbcr */
>  	return crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420
> ||
>  		(crtc_state->output_format ==
> INTEL_OUTPUT_FORMAT_YCBCR444 &&
>  		 intel_dp->dfp.ycbcr_444_to_420);
> @@ -2574,6 +2575,7 @@ void intel_dp_configure_protocol_converter(struct
> intel_dp *intel_dp,
>  			    "Failed to %s protocol converter YCbCr 4:2:0 conversion
> mode\n",
>  			    str_enable_disable(intel_dp->dfp.ycbcr_444_to_420));
> 
> +	/* FIXME see intel_dp_update_420() regarding rgb_to_ycbcr */
>  	tmp = intel_dp->dfp.rgb_to_ycbcr ?
>  		DP_CONVERSION_BT709_RGB_YCBCR_ENABLE : 0;
> 
> @@ -4430,6 +4432,14 @@ intel_dp_update_420(struct intel_dp *intel_dp)
>  	rgb_to_ycbcr = drm_dp_downstream_rgb_to_ycbcr_conversion(intel_dp-
> >dpcd,
>  								 intel_dp-
> >downstream_ports,
> 
> DP_DS_HDMI_BT709_RGB_YCBCR_CONV);
> +	/*
> +	 * FIXME need to actually track whether we're really
> +	 * going to be doing the RGB->YCbCr connversion or not.
> +	 * We can't tell by simply looking at intel_dp->dfp.rgb_to_ycbcr.
> +	 * Readout is going to annoying due to having to read that
> +	 * state from external hardware that may vanish at any time :(
> +	 */
> +	rgb_to_ycbcr = false;

I think this will break 8k yuv pcon case as of now.
@Nautiyal, Ankit K Can we get that fixed. We will need 8k YUV from source due to
bandwidth constraints.

Rest of the series all looks nice and good.

Regards,
Uma Shankar

>  	if (DISPLAY_VER(i915) >= 11) {
>  		/* Let PCON convert from RGB->YCbCr if possible */
> --
> 2.34.1