[Intel-gfx] [PATCH 10/13] drm/i915: Disable DSB usage specifically for LUTs

[Nautiyal, Ankit K]

LGTM.

Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>

On 11/23/2022 8:56 PM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> The DSB has problem loading the LUTs at the moment. Some
> of that is due to the palette anti collision logic, some
> due to what seem real hw issues. Disable it the whole
> thing locally in the color management code for now.
>
> Note that we currently have this weird situation where on
> adl+ we load parts of the LUT with DSB and parts with mmio.
> That is due to the fact that only some parts of the LUT code
> are using the DSB register write functions (ivb_load_lut_ext*()),
> while the rest is using pure mmio (bdw_load_lut_10()). So now
> we'll go back to pure mmio temporarily, until the DSB issues
> get fixed (at which point we should be going for pure DSB).
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_color.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
> index 2715f1b617e1..9978d21f1634 100644
> --- a/drivers/gpu/drm/i915/display/intel_color.c
> +++ b/drivers/gpu/drm/i915/display/intel_color.c
> @@ -1394,6 +1394,9 @@ void intel_color_prepare_commit(struct intel_crtc_state *crtc_state)
>   {
>   	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>   
> +	/* FIXME DSB has issues loading LUTs, disable it for now */
> +	return;
> +
>   	crtc_state->dsb = intel_dsb_prepare(crtc);
>   }
>