Screen brightness is not maintained after reboot

[natan2021 (Natanael Medrado)]

Hey guys! I know there is a thread on this forum in the f32 section about this, but I don’t understand and I don’t even know the best way to proceed to modify this adjustment in Grub or in the System. After System reboot, the brightness level always returns to maximum.

[manan (Manan Gupta)]

I have the same problem on Fedora 35 Silverblue. Online resources either mention changing /sys/class/backlight/intel_backlight/brightness or by changing GRUB setting, both of which are immutable locations on Silverblue.

https://discussion.fedoraproject.org/t/maximum-screen-brightness-every-boot-up/77878

I ran systemctl status systemd-backlight@backlight:intel_backlight.service to get the output:

systemd-backlight@backlight:intel_backlight.service - Load/Save Screen Backlight Brightness of backlight:intel_backlight
     Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
     Active: failed (Result: exit-code) since Tue 2022-04-12 21:05:15 IST; 14h ago
       Docs: man:systemd-backlight@.service(8)
    Process: 675 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:intel_backlight (code=exited, status=238/STATE_DIRECTORY)
   Main PID: 675 (code=exited, status=238/STATE_DIRECTORY)
        CPU: 2ms

Apr 12 21:05:15 fedora systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:intel_backlight...
Apr 12 21:05:15 fedora systemd[675]: systemd-backlight@backlight:intel_backlight.service: Failed to set up special execution directory in /var/lib: Read-only file system
Apr 12 21:05:15 fedora systemd[675]: systemd-backlight@backlight:intel_backlight.service: Failed at step STATE_DIRECTORY spawning /usr/lib/systemd/systemd-backlight: Read-only file system
Apr 12 21:05:15 fedora systemd[1]: systemd-backlight@backlight:intel_backlight.service: Main process exited, code=exited, status=238/STATE_DIRECTORY
Apr 12 21:05:15 fedora systemd[1]: systemd-backlight@backlight:intel_backlight.service: Failed with result 'exit-code'.
Apr 12 21:05:15 fedora systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:intel_backlight.

Can anyone tell me how to fix this correctly on Silverblue?

[manan (Manan Gupta)]

Found a solution that works for me.

Brightness service doesn't start in Fedora Silverblue 35

I’m seeing this same issue, but I hadn’t had a chance to dig into it. Thanks for pointing out that service failure, @dr0hith! It does look like Silverblue has something set to read-only that the systemd-backlight service needs to write to. I don’t know if the fix would be as simple as setting that to rw long enough to set it and then back to ro, or if it’s something bigger where really systemd-backlight needs to be writing that information somewhere else. Can anyone chime in as to whether a …

The systemd service just has to be restarted once and then it seems to work fine. Copying the command here for easy access:

sudo systemctl restart systemd-backlight@backlight:intel_backlight.service