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

Ville Syrjala
2026-03-30T23:54:29Z

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>
---
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");

--
2.52.0