Arch Linux

average sitter

Member

Registered: 2024-07-30

Posts: 3

Backlight doesn't turn on after system wakes up from suspend

I have a fresh arch install with Wayland kde on a Redmi Book Pro15.

After clicking sleep or closing the lid and waking up the device, the screen becomes very dim. I can only see the contents when shining a flashlight into it. It seems the backlight did not turn back on after suspension. Only a hard shutdown fixes it (even reboot by ssh doesn't work).

I have a dedicated graphics Nvidia RTX 2050 using proprietary drivers. However, kde is using integrated intel graphics.

This is the full journal: https://pastebin.com/5CBGPUQR
There are a few kernel warnings that says something about nv_queue Tainted. But I don't think that is related. Other than this, I didn't notice any other related errors.

I have tried changing the kernel to lts, but it does not work.

seth

Member

Registered: 2012-09-03

Posts: 59,882

Re: Backlight doesn't turn on after system wakes up from suspend

Do you generally have backlight control?
https://wiki.archlinux.org/title/Backlight

Can you control the backlight instead of rebooting?

Aug 05 11:39:05 woop systemd[1]: Reached target Sleep.
Aug 05 11:39:14 woop systemd[1]: Stopped target Sleep.
Aug 05 11:55:59 woop systemd[1]: Reached target Sleep.
Aug 05 13:47:03 woop systemd[1]: Stopped target Sleep.
Aug 05 14:03:45 woop systemd[1]: Reached target Sleep.
Aug 05 18:25:01 woop systemd[1]: Stopped target Sleep.

there're 3 sleep cycles in that journal, is the problem deterministic or intermittent?

You've been fooling around w/ the systemd backlight services, but

Aug 05 18:25:02 woop systemd[1]: Started dbus-:1.2-org.kde.powerdevil.backlighthelper@7.service.

there're relevant powerdevil services - can you reproduce this outside a KDE session? (multi-user.target, openbox)?

---

How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc

average sitter

Member

Registered: 2024-07-30

Posts: 3

Re: Backlight doesn't turn on after system wakes up from suspend

Yes. I can control the backlight by echoing into /sys/class/backlight/intel_backlight/brightness
It works until I suspend and wake up. When I set this value after waking up, there is no effect, the screen stays dark no matter what value it is.

The problem occurs every time, not intermittent.

I also tried

systemctl isolate multi-user.target

and ran

systemctl suspend

which yielded the same result. So this should not be a kde problem.

seth

Member

Registered: 2012-09-03

Posts: 59,882

Re: Backlight doesn't turn on after system wakes up from suspend

Tried to *lower* the backlight?
https://wiki.archlinux.org/title/Backli … i915_only)

Tried dpcd?
https://wiki.archlinux.org/title/Backli … i915_only)

---

How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc

average sitter

Member

Registered: 2024-07-30

Posts: 3

Re: Backlight doesn't turn on after system wakes up from suspend

Nope. Read the whole page. Those aren't the problem.