Re: [v2,2/9] drm/i915/scaler: Adjust pipe scaler scale factors for 4:2:0 ouput

["Michał Grzelak" <michal.grzelak@intel.com>]

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Nit: title: s/ouput/output/

On Wed, 29 Oct 2025, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> 4:2:0 output effectively involves an extra downscale factor of
> 2x2 due to the chroma downsampling. Adjust the stored scaler
> scale factors accodingly.

Even nitter nit: s/accodingly/accordingly

If this was already pushed then please disregard the comment.

Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>

BR,
Michał

>
> Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> drivers/gpu/drm/i915/display/skl_scaler.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/skl_scaler.c b/drivers/gpu/drm/i915/display/skl_scaler.c
> index 640c65818f8a..e8a8facdc300 100644
> --- a/drivers/gpu/drm/i915/display/skl_scaler.c
> +++ b/drivers/gpu/drm/i915/display/skl_scaler.c
> @@ -499,6 +499,15 @@ static int intel_atomic_setup_scaler(struct intel_crtc_state *crtc_state,
>
> 			return -EINVAL;
> 		}
> +
> +		/*
> +		 * For the purposes of prefill 4:2:0 chroma
> +		 * subsampling is considered a 2x2 downscale.
> +		 */
> +		if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
> +			hscale <<= 1;
> +			vscale <<= 1;
> +		}
> 	}
>
> 	scaler_state->scalers[*scaler_id].hscale = hscale;
>