On 1/26/26 8:23 PM, Nícolas F. R. A. Prado wrote:
> On Fri, 2025-12-19 at 23:46 +0200, Cristian Ciocaltea wrote:
>> Some display controllers can be hardware programmed to show non-black
>> colors for pixels that are either not covered by any plane or are
>> exposed through transparent regions of higher planes. This feature
>> can
>> help reduce memory bandwidth usage, e.g. in compositors managing a UI
>> with a solid background color while using smaller planes to render
>> the
>> remaining content.
>>
>> To support this capability, introduce the BACKGROUND_COLOR standard
>> DRM
>> mode property, which can be attached to a CRTC through the
>> drm_crtc_attach_background_color_property() helper function.
>>
>> Additionally, define a 64-bit ARGB format value to be built with the
>> help of a couple of dedicated DRM_ARGB64_PREP*() helpers. Individual
>> color components can be extracted with desired precision using the
>> corresponding DRM_ARGB64_GET*() macros.
>>
>> Co-developed-by: Matt Roper <[email protected]>
>> Signed-off-by: Matt Roper <[email protected]>
>> Signed-off-by: Cristian Ciocaltea <[email protected]>
>> ---
>> drivers/gpu/drm/drm_atomic_state_helper.c | 1 +
>> drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
>> drivers/gpu/drm/drm_blend.c | 39 ++++++++++++++++--
>> drivers/gpu/drm/drm_mode_config.c | 6 +++
>> include/drm/drm_blend.h | 4 +-
>> include/drm/drm_crtc.h | 12 ++++++
>> include/drm/drm_mode_config.h | 5 +++
>> include/uapi/drm/drm_mode.h | 67
>> +++++++++++++++++++++++++++++++
>> 8 files changed, 133 insertions(+), 5 deletions(-)
>
> You should also add a dump for this property in
> drm_atomic_crtc_print_state().
This and all your other comments have been addressed in v5 [1].
$ grep background_color -B13 /sys/kernel/debug/dri/display-subsystem/state
crtc[82]: video_port0
enable=1
active=1
self_refresh_active=0
planes_changed=1
mode_changed=0
active_changed=0
connectors_changed=0
color_mgmt_changed=0
plane_mask=1
connector_mask=1
encoder_mask=1
mode: "3840x2160": 60 594000 3840 4016 4104 4400 2160 2168 2178 2250
0x48 0x9
background_color=ffff000000000000
Thanks,
Cristian
[1]
https://lore.kernel.org/all/[email protected]/
