steam deck / vangogh internal screen backlight not turning off when dpms off is issued since kernel v6.1

changed the description

I'd suspect this is caused specifically by 9c75891feef0 ("drm/amd/display: rework recent update PHY state commit"). Can you please confirm by comparing a build from 9c75891feef0 and another from 9c75891feef0~1?

Thanks for the quick response, here are the test results:

Kernel Version	Internal screen backlight turns off when dpms off is issued
10faf07871b2 (9c75891feef0~1)	yes
9c75891feef0	no

Thanks; it confirms it's caused by that commit as I suspected.

added DC label

added Vangogh bisected labels

mentioned in issue #2645 (closed)

Hi @katharinechui,do you have any steps to reproduce this issue?

If a Xorg session is handy, Xorg can be instructed to suspend screens immediately by xset dpms force off, that's what I used when I was comparing kernels.

Start with a Xorg session (KDE in my case), set screen to a relatively higher brightness so that if the backlight stays on it is noticeable
In the session, run xset dpms force off; sleep 1; cat /sys/class/drm/card*-eDP-1/dpms
Observe the panel to see if backlight stays on
Wake the screen again with any input after a few seconds, verify the output in step 2 to make sure that dpms was actually set to Off if the backlight stays on

Toggling dpms immediately in Wayland sessions requires DE dependent methods.

Alternatively with most DE, in Wayland and Xorg, with an external screen connected, disabling the internal screen would set dpms to off.

There's also vbetool dpms off, but vbetool is not commonly packaged in distros. This tool should be directly setting dpms without going through a display server but I have not used it in my testing.

@katharinechui can you see if the following patch fixes the issue for you? https://patchwork.freedesktop.org/patch/553750/

Thanks for the update, sadly the behavior remains the same after applying the commit on top of 6.4.12 (05d8970cca014b96c06c3730ae084f08087f13dd)

Does it require other commits?

If your display supports aux backlight control, you will also need the following patch: https://patchwork.freedesktop.org/patch/555977/.

I have no idea whether the steamdeck supports that, while applying both patches on top of 6.5.2(3766ec12cf894667026786fef355bb998c263f03) didn't help, the issue persists sadly.