Arch Linux

kauron

Member

Registered: 2015-12-01

Posts: 11

Laptop screen's backlight turns off randomly

Hi there,

I'm having a weird problem with my laptop's screen. Its backlight randomly turns off.

The following fixes work immediately:

• Reboot.

• Change to tty.

• Turn the screen of and back on with `xrandr`.

My setup is the following (all updates have been applied):

• Thinkpad T14s (AMD 3rd gen)

• WM: i3 (under X11), using

• Kernel: linux-lts.

Does anyone have any idea what may be causing this issue, how to investigate further and how to fix it?

Thanks in advance :D

ranurag

Member

Registered: 2023-07-21

Posts: 59

Re: Laptop screen's backlight turns off randomly

> journalctl -b 

Also search for brightness(file)  in /sys/class/backlight
and set it from with the desired value.
https://wiki.archlinux.org/title/backlight

Last edited by ranurag (2023-09-09 08:02:02)

kauron

Member

Registered: 2015-12-01

Posts: 11

Re: Laptop screen's backlight turns off randomly

This event happened a few minutes ago, and no (related) messages appeared in journalctl at that time:

sep 09 10:28:33 polaris systemd[1]: fprintd.service: Deactivated successfully.
sep 09 10:39:29 polaris wpa_supplicant[999]: wlan0: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-57 noise=-109 txrate=104000
sep 09 10:51:36 polaris systemd-resolved[737]: Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.20.1.
sep 09 11:35:10 polaris dbus-daemon[751]: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service' requested by ':1.5256' (uid=1000 pid=1352018 comm="hostnamectl hostname")
sep 09 11:35:10 polaris systemd[1]: Starting Hostname Service...
sep 09 11:35:10 polaris dbus-daemon[751]: [system] Successfully activated service 'org.freedesktop.hostname1'
sep 09 11:35:10 polaris systemd[1]: Started Hostname Service.

The occurrence was around 11:35, but I think that the "Starting Hostname Service" is related to checking the journal with journalctl.

I've also realized that this problem only occurs when I'm watching video or playing videogames, in other words, when the GPU is being used. In my case, its integrated graphics (AMD Ryzen 7 PRO 6850U with Radeon Graphics). It occurs on battery and while plugged-in.

I've prepared a script to zip the contents of /sys/class/backlight, I'll try it next time it happens. Changing the backlight with xbacklight does not work, so I suppose changing the files directly won't either.

Last edited by kauron (2023-09-09 10:05:28)

ranurag

Member

Registered: 2023-07-21

Posts: 59

Re: Laptop screen's backlight turns off randomly

> journalctl -b > temp.xyz && curl -F"file=@temp.xyz" 0x0.st 

> acpi -V

Docbroke

Member

From: India

Registered: 2015-06-13

Posts: 1,438

Re: Laptop screen's backlight turns off randomly

Have you tried

xset -dpms

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kauron

Member

Registered: 2015-12-01

Posts: 11

Re: Laptop screen's backlight turns off randomly

Hi again, thanks for the suggestions, I've gathered more data.

First, here are the logs since last boot: http://0x0.st/Hf4A.log
I've tried setting a brightness level by writing to /sys/class/backlight/*/brightness, but it does not work.
xset -dpms doesn't work either (the screen is on, I can see the color of the pixels, it's just the backlight that's off).

The output of acpi doesn't show anything interesting either:

Battery 0: Not charging, 74%
Battery 0: design capacity 3504 mAh, last full capacity 3139 mAh = 89%
Adapter 0: on-line
Thermal 0: ok, 20.0 degrees C
Thermal 0: trip point 0 switches to mode critical at temperature 110.0 degrees C
Cooling 0: Processor 0 of 0
Cooling 1: Processor 0 of 0
Cooling 2: Processor 0 of 0
Cooling 3: ath11k_thermal 0 of 100
Cooling 4: Processor 0 of 0
Cooling 5: Processor 0 of 0
Cooling 6: Processor 0 of 0
Cooling 7: Fan 1 of 1
Cooling 8: Processor 0 of 0
Cooling 9: Processor 0 of 0
Cooling 10: Processor 0 of 0
Cooling 11: Processor 0 of 0
Cooling 12: Processor 0 of 0
Cooling 13: Processor 0 of 0
Cooling 14: Processor 0 of 0
Cooling 15: Processor 0 of 0
Cooling 16: Processor 0 of 0
Cooling 17: Processor 0 of 0

The only thing that works is disabling the screen via xrandr and re-enabling it. Rebooting also works, and switching to tty does not work (I was mistaken in my OP).

Docbroke

Member

From: India

Registered: 2015-06-13

Posts: 1,438

Re: Laptop screen's backlight turns off randomly

I've also realized that this problem only occurs when I'm watching video or playing videogames, in other words, when the GPU is being used. In my case, its integrated graphics (AMD Ryzen 7 PRO 6850U with Radeon Graphics). It occurs on battery and while plugged-in.

Put this in kernel command line and see if it solves the issue

amd_pstate=passive

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kauron

Member

Registered: 2015-12-01

Posts: 11

Re: Laptop screen's backlight turns off randomly

I already have this option set on boot.

Docbroke

Member

From: India

Registered: 2015-06-13

Posts: 1,438

Re: Laptop screen's backlight turns off randomly

If you are on using 'linux' kernel (not lts), you can also try amd_pstate=active, or try removing that option.

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nicko888

Member

Registered: 2023-09-27

Posts: 1

Re: Laptop screen's backlight turns off randomly

@kauron, have you managed to solve this? I have the same laptop and a similar setup and I'm also experiencing this issue.
It appeared quite some time ago (perhaps, even before I switched to amd pstate driver), so setting amd_pstate=active/passive does not help.

I found that suspending and resuming a laptop also helps, but it's still annoying...

kauron

Member

Registered: 2015-12-01

Posts: 11

Re: Laptop screen's backlight turns off randomly

I have tried both amd_pstate=passive and removing the option, but still haven't managed to fix it... I'll post on this thread if I eventually resolve it.

derptank

Member

Registered: 2017-09-14

Posts: 1

Re: Laptop screen's backlight turns off randomly

I appear to have the same issue, also a T14s with the same CPU and integrated GPU. Kernel 6.1. I have not tried the amd_pstate option.
Switching to tty worked once but not the second time (without rebooting in between), I put cycled through sleep mode to get the backlight back.

I will switch to kernel 6.5 an see it that helps.

hoschi

Member

From: Ulm (Germany)

Registered: 2008-11-03

Posts: 474

Re: Laptop screen's backlight turns off randomly

ThinkPad X13 Gen3 (AMD) here, same issue
Any new insights?

// edit
My workaround is Fn + 4 (Suspend) and Fn again (Resume).

Last edited by hoschi (2023-11-01 18:43:35)

hoschi

Member

From: Ulm (Germany)

Registered: 2008-11-03

Posts: 474

Re: Laptop screen's backlight turns off randomly

Another one, here a T16.
https://forums.lenovo.com/t5/Other-Linu … -p/5260463