[PATCH 8/9] drm/i915/hdmi: Make the RGB fallback for "4:2:0 only" modes the last resort

Ville Syrjala
2026-03-30T23:54:24Z

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_hdmi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index 95bd38c620d1..6bc1689cbf93 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -2314,7 +2314,7 @@ static int intel_hdmi_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