Re: [PATCH 9/9] drm/i915/dp: Make the RGB fallback for "4:2:0 only" modes the last resort

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 3/31/2026 5:23 AM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Currently we take the Hail Mary RGB fallback for "4:2:0 only" modes
> already during the first pass when respect_downstream_limits==true.
> It seems better to try everything else first (like ignoring TMDS
> clock limits) while still preferring 4:2:0, and only if everything
> else has failed fall back to RGB.
>
> Cc: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>


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


> ---
>   drivers/gpu/drm/i915/display/intel_dp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index ed89fbcdd549..e23162fc3f8b 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3405,7 +3405,7 @@ intel_dp_compute_formats(struct intel_encoder *encoder,
>   						     respect_downstream_limits,
>   						     INTEL_OUTPUT_FORMAT_YCBCR420);
>   
> -		if (ret) {
> +		if (ret && !respect_downstream_limits) {
>   			drm_dbg_kms(display->drm,
>   				    "YCbCr 4:2:0 mode but YCbCr 4:2:0 output not possible. Falling back to RGB.\n");
>