Systemd backlight service failed

Looking at systemctl --failed I noticed

[morten@endeavour ~]$ systemctl --failed
  UNIT                                            LOAD   ACTIVE SUB    DESCRIPTION                                                   
● systemd-backlight@backlight:acpi_video0.service loaded failed failed Load/Save Screen Backlight Brightness of backlight:acpi_video0
● systemd-backlight@backlight:amdgpu_bl0.service  loaded failed failed Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0 

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.
2 loaded units listed.
[morten@endeavour ~]$ 

Checking the status and PID of each results in

[morten@endeavour ~]$ systemctl status systemd-backlight@backlight:acpi_video0.service
● systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: failed (Result: exit-code) since Sat 2021-02-06 01:00:59 CET; 4min 53s ago
       Docs: man:systemd-backlight@.service(8)
    Process: 866 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=1/FAILURE)
   Main PID: 866 (code=exited, status=1/FAILURE)

Feb 06 01:00:59 endeavour systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Feb 06 01:00:59 endeavour systemd-backlight[866]: Failed to get backlight or LED device 'backlight:acpi_video0': No such device
Feb 06 01:00:59 endeavour systemd[1]: systemd-backlight@backlight:acpi_video0.service: Main process exited, code=exited, status=1/FAILURE
Feb 06 01:00:59 endeavour systemd[1]: systemd-backlight@backlight:acpi_video0.service: Failed with result 'exit-code'.
Feb 06 01:00:59 endeavour systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.
[morten@endeavour ~]$ journalctl -b _PID=866
-- Journal begins at Fri 2021-01-29 23:10:50 CET, ends at Sat 2021-02-06 01:04:20 CET. --
Feb 06 01:00:59 endeavour systemd-backlight[866]: Failed to get backlight or LED device 'backlight:acpi_video0': No such device
[morten@endeavour ~]$ systemctl status systemd-backlight@backlight:amdgpu_bl0.service
● systemd-backlight@backlight:amdgpu_bl0.service - Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: failed (Result: exit-code) since Sat 2021-02-06 01:00:59 CET; 5min ago
       Docs: man:systemd-backlight@.service(8)
    Process: 867 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:amdgpu_bl0 (code=exited, status=1/FAILURE)
   Main PID: 867 (code=exited, status=1/FAILURE)

Feb 06 01:00:59 endeavour systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0...
Feb 06 01:00:59 endeavour systemd-backlight[867]: amdgpu_bl0: Failed to write system 'brightness' attribute: No such device or address
Feb 06 01:00:59 endeavour systemd[1]: systemd-backlight@backlight:amdgpu_bl0.service: Main process exited, code=exited, status=1/FAILURE
Feb 06 01:00:59 endeavour systemd[1]: systemd-backlight@backlight:amdgpu_bl0.service: Failed with result 'exit-code'.
Feb 06 01:00:59 endeavour systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0.
[morten@endeavour ~]$ journalctl -b _PID=867
-- Journal begins at Fri 2021-01-29 23:10:50 CET, ends at Sat 2021-02-06 01:04:20 CET. --
Feb 06 01:00:59 endeavour systemd-backlight[867]: amdgpu_bl0: Failed to write system 'brightness' attribute: No such device or address

I’ve looked a little online, but fixed like https://unix.stackexchange.com/questions/393185/backlightacpi-video0-no-such-device just disable my backlight control in return for removing the error message.

You likely need to set the correct backlight type for your laptop. Have a search on the Arch wiki for your make and model and see what you can find.

(I’d have done that rather than posting this reply, but I have no idea what your laptop is.)

@morten_nissov
If you add the following kernel parameter In the default grub command line in

/etc/default/grub

acpi_backlight=video

Then update grub with

sudo grub-mkconfig -o /boot/grub/grub.cfg

2 Likes

doing this removes control over the backlight, now it’s stuck at 100% even though the gnome display thinks I’m lowering it.

I have a thinkpad E495, I don’t think theres any specific pages for this on the arch wiki, at least not here https://wiki.archlinux.org/index.php/Laptop/Lenovo#E_series.

Note: I have discovered I can write sudo systemctl start systemd-backlight@backlight:amdgpu_bl0 and this avoid one failure, although I do not believe there is a service for amdgpu_bl0 so it does not persist under rebooting.

You could try a different parameter such as
Example:
acpi_backlight=vendor

The one i provided works on my HP with amdgpu

Is there a way to determine which parameter to use? Some CL functions?

I had both of these on my HP also but the parameter i first gave works for me.

This also prohibited me from changing the brightness, though also with a visual glitch in the indicator in that increase/decreasing was limited to the lowest 10% of the status bar, still with no change in real brightness.

I think it is this bug.

https://wiki.archlinux.org/index.php/backlight#Backlight_is_always_at_full_brightness_after_a_reboot_with_amdgpu_driver

1 Like

On my HP i was able to turn off the systemd-backlight@backlight : amdgpu_bl0 and then i used the kernel parameter in the grub command line,

acpi_backlight=video

This works perfectly on my HP

turning off systemd-backlight@backlight : amdgpu_bl0 by writing some systemctl disable systemd-backlight@backlight:amdgpu_bl0?

Yes …that’s what i did. Just disabled it. Then i tried the parameter with vendor which didn’t work and then i tried video and it works. I can adjust the backlight with the f keys up and down. It default pretty low about 14-20% and i can raise or lower it,

Disabling amdgpu_bl0 and setting acpi_backlight=video in /etc/default/grub still results in a very bright screen which doesn’t respond to the f keys.

I can try with the fix-brightness solution?

Did you try this one

acpi_backlight=vendor

Just tried, still doesn’t work, it’s the same as before where the error message in systemctl disappears but I lose control of the screen brightness.

I noticed however,

[morten@endeavour ~]$ systemctl status systemd-backlight@backlight:amdgpu_bl0
● systemd-backlight@backlight:amdgpu_bl0.service - Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: active (exited) since Sat 2021-02-06 09:37:29 CET; 1min 40s ago
       Docs: man:systemd-backlight@.service(8)
    Process: 952 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:amdgpu_bl0 (code=exited, status=0/SUCCESS)
   Main PID: 952 (code=exited, status=0/SUCCESS)

Feb 06 09:37:29 endeavour systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0...
Feb 06 09:37:29 endeavour systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0.

this is the case after I had tried boh sudo systemctl disable systemd-backlight@backlight:amdgpu_bl0 and sudo systemctl disable systemd-backlight@backlight:amdgpu_bl0.service.

Yes i got that on mine also a few times. But now it’s say’s dead not active. I think it’s service.

This time when I rebooted there were no errors, I’m not really sure what I’ve done to cause this.

[morten@endeavour ~]$ systemctl --failed 
  UNIT LOAD ACTIVE SUB DESCRIPTION
0 loaded units listed.

Especially considering I think everything is in its “vanilla” state with respect to changes we’ve been discussing.

[morten@endeavour ~]$ cat /etc/default/grub
# GRUB boot loader configuration

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="EndeavourOS"
GRUB_CMDLINE_LINUX_DEFAULT="quiet loglevel=3 nowatchdog"
GRUB_CMDLINE_LINUX=""
[morten@endeavour ~]$ systemctl status systemd-backlight@backlight:acpi_video0.service
● systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: active (exited) since Sat 2021-02-06 09:47:52 CET; 1min 25s ago
       Docs: man:systemd-backlight@.service(8)
    Process: 285 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=0/SUCCESS)
   Main PID: 285 (code=exited, status=0/SUCCESS)

Feb 06 09:47:52 endeavour systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Feb 06 09:47:52 endeavour systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:acpi_video0.
[morten@endeavour ~]$ systemctl status systemd-backlight@backlight:amdgpu_bl0.service
● systemd-backlight@backlight:amdgpu_bl0.service - Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: active (exited) since Sat 2021-02-06 09:47:55 CET; 1min 28s ago
       Docs: man:systemd-backlight@.service(8)
    Process: 943 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:amdgpu_bl0 (code=exited, status=0/SUCCESS)
   Main PID: 943 (code=exited, status=0/SUCCESS)

Feb 06 09:47:55 endeavour systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0...
Feb 06 09:47:55 endeavour systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0.

Mine is the same no errors.

Edit: So i have acpi_backlight=video

[ricklinux@eos-kde ~]$ systemctl status systemd-backlight@backlight:amdgpu_bl0.service
● systemd-backlight@backlight:amdgpu_bl0.service - Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: active (exited) since Sat 2021-02-06 03:40:20 EST; 14min ago
       Docs: man:systemd-backlight@.service(8)
    Process: 836 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:amdgpu_bl0 (code=exited, status=0/SUCCESS)
   Main PID: 836 (code=exited, status=0/SUCCESS)

Feb 06 03:40:20 eos-kde systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0...
Feb 06 03:40:20 eos-kde systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:amdgpu_bl0.
[ricklinux@eos-kde ~]$ 
[ricklinux@eos-kde ~]$ systemctl status systemd-backlight@backlight:acpi_video0.service
● systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: active (exited) since Sat 2021-02-06 03:40:16 EST; 17min ago
       Docs: man:systemd-backlight@.service(8)
    Process: 294 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=0/SUCCESS)
   Main PID: 294 (code=exited, status=0/SUCCESS)

Feb 06 03:40:16 eos-kde systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Feb 06 03:40:16 eos-kde systemd[1]: Finished Load/Save Screen Backlight Brightness of backlight:acpi_video0.
[ricklinux@eos-kde ~]$