Hi Diederik,

On 1/7/26 2:18 PM, Diederik de Haas wrote:

Hi,

On Tue Nov 18, 2025 at 12:51 AM CET, Cristian Ciocaltea wrote:

quoted

Some display controllers can be hardware-configured to present non-black
colors for pixels which are not covered by any plane (or are exposed
through transparent regions of higher planes).
...
The subsequent patches add background color support to VKMS and the VOP2
display controller used in the RK3568, RK3576, and RK3588 Rockchip SoC
families.

Cristian provided a helper script which would show a test pattern and
then iterate through setting Red, Green, Blue background color and then
set it back to the original value.

I first tested this on a Rock 5B (RK3588).
Without this patch set, the background color was Black with every
iteration. But with this patch set, I did see a Red, Green and Blue
background color, after which it was set back to Black.

diederik@rock5b:~$ grep -E "^Changing prop|^Read BACKGROUND_COLOR" bgcol-test-bash-user.log
Read BACKGROUND_COLOR prop (ARGB64): 0xffff000000000000
Changing prop value to: 0xffff00000000ffff
Read BACKGROUND_COLOR prop (ARGB64): 0xffff00000000ffff
Changing prop value to 0xffffffff00000000
Read BACKGROUND_COLOR prop (ARGB64): 0xffffffff00000000
Changing prop value to 0xffff0000ffff0000
Read BACKGROUND_COLOR prop (ARGB64): 0xffff0000ffff0000
Changing prop value to 0xffff00000000ffff
Read BACKGROUND_COLOR prop (ARGB64): 0xffff00000000ffff
Changing prop value to: 0xffff000000000000
Read BACKGROUND_COLOR prop (ARGB64): 0xffff000000000000

I then did the same test on a Quartz64-B (RK3566) and that too showed a
Red, Green and Blue background color and then was set back to Black.

diederik@quartz64b:~$ grep -E "^Changing prop|^Read BACKGROUND_COLOR" bgcol-test-bash-user-q64b.log
Read BACKGROUND_COLOR prop (ARGB64): 0xffff000000000000
Changing prop value to: 0xffff00000000ffff
Read BACKGROUND_COLOR prop (ARGB64): 0xffff00000000ffff
Changing prop value to 0xffffffff00000000
Read BACKGROUND_COLOR prop (ARGB64): 0xffffffff00000000
Changing prop value to 0xffff0000ffff0000
Read BACKGROUND_COLOR prop (ARGB64): 0xffff0000ffff0000
Changing prop value to 0xffff00000000ffff
Read BACKGROUND_COLOR prop (ARGB64): 0xffff00000000ffff
Changing prop value to: 0xffff000000000000
Read BACKGROUND_COLOR prop (ARGB64): 0xffff000000000000

So this patch set does what it is supposed to do, so feel free to add:

Tested-by: Diederik de Haas <redacted>

Thanks for taking the time to test this!

Please note there's a newer revision of the series:

https://lore.kernel.org/all/20251219-rk3588-bgcolor-v4-0-2ff1127ea757@collabora.com/ (local)

Regards,
Cristian