[PATCH 0/2] Make HDMI state helpers handle odd max bpc requests

[Nicolas Frattaroli <nicolas.frattaroli@collabora.com>]

With the "max bpc" KMS connector property, userspace can arbitrarily
restrict the upper end of the bits-per-component range. This is fine and
good, except the HDMI state helpers never considered that max_bpc could
be influenced by a userspace setting, so assumed it'll always be an even
value from the HDMI standards.

This, unfortunately, is not the world we live in anymore. Patch 1
corrects sink_supports_format_bpc to return false on BPCs outside of
what HDMI allows. Patch 2 then corrects handling of odd-numbered max
bpcs by rounding the loop start value down to an even number instead. It
also adds a KUnit test to make sure nobody breaks this again in the
future.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
Nicolas Frattaroli (2):
      drm/display: hdmi: Only allow BPC values of 8, 10, 12 and 16
      drm/display: hdmi: Round odd max_bpc down to even numbers

 drivers/gpu/drm/display/drm_hdmi_state_helper.c    | 12 +++-
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 71 ++++++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)
---
base-commit: be3e81d74654555fff2779d78848267bd50dcf51
change-id: 20260608-hdmi-max-bpc-fix-703019763834

Best regards,
--  
Nicolas Frattaroli <nicolas.frattaroli@collabora.com>