udev rules not working on Arch about brightnessctl HOT 20 CLOSED

Is it still broken in brightnessctl in community?

community/brightnessctl 0.4-2 is working for me, my issue was not having my user in the video` group

For anyone else who finds this thread: sudo usermod -aG video $USER then logout and back in to add yourself to the video group

from brightnessctl.

since systemd 243 you don't need any special permissions on the system to change the backlight brightness. a user can do it for their seat by dbus calling logind.

this is already supported in brightnessctl, but we are waiting for a 0.5 release (hint hint @Hummer12007)

from brightnessctl.

I've used the change action instead of the add and everything works:

    ACTION=="change", SUBSYSTEM=="backlight", KERNEL=="radeon_b10", RUN+="/usr/bin/chgrp video /sys/class/backlight/%k/brightness"
    ACTION=="change", SUBSYSTEM=="backlight", KERNEL=="radeon_b10", RUN+="/usr/bin/chmod g+w /sys/class/backlight/%k/brightness"

from brightnessctl.

I know this is a bit old, and this has seemingly been fixed on systems with a newer version of systemd, but this is a working solution in the meantime: Instead of chgrp, you can use chgrp -h to avoid dereferencing the symlink.

from brightnessctl.

What does ls -l /sys/class/backlight/intel_backlight/ output?

from brightnessctl.

ls -l /sys/class/backlight/intel_backlight/ returns

total 0
-r--r--r-- 1 root root 4096 Sep  4 10:24 actual_brightness
-rw-r--r-- 1 root root 4096 Sep  4 10:24 bl_power
-rw-r--r-- 1 root root 4096 Sep  4 10:54 brightness
lrwxrwxrwx 1 root root    0 Sep  4 10:24 device -> ../../card0-eDP-1
-r--r--r-- 1 root root 4096 Sep  4 10:24 max_brightness
drwxr-xr-x 2 root root    0 Sep  4 10:58 power
lrwxrwxrwx 1 root root    0 Sep  4 10:24 subsystem -> ../../../../../../../class/backlight
-r--r--r-- 1 root root 4096 Sep  4 10:24 type
-rw-r--r-- 1 root root 4096 Sep  4 10:24 uevent

from brightnessctl.

Let me double-check with you: are you executing the /bin/chgrp video /sys/class/backlight/%k/brightness in the shell, as opposed to adding udev rules?

from brightnessctl.

I noticed the udev rule wasn't allowing the script to run without root privileges properly, so I ran the commands it was supposed to in the shell just to get some information for an issue report. (I'm new to troubleshooting udev rules.)

from brightnessctl.

I see, how weird. For the record, udev replaces %k with the device name (intel_backlight in this case).

from brightnessctl.

Can you try it on the latest commit btw? (i.e. reinstall brightnessctl and reboot)

from brightnessctl.

Done. No dice. (All I see is a version bump in the commits, so I don't think that will help much.)

from brightnessctl.

And another question. Is your user account in the video group?

from brightnessctl.

It wasn't, but I just added it and there was no effect.

from brightnessctl.

It happens to me too, but adding a sudo rule does not work. Arch up-to-date kernel 4.18.6

from brightnessctl.

The proper way is to set the udev rules with uaccess:

ACTION=="add", SUBSYSTEM=="backlight", TAG+="uaccess"
ACTION=="add", SUBSYSTEM=="leds", TAG+="uaccess"

(edit: which (acls) is not supported on sysfs sigh)

from brightnessctl.

I have faced this issue. Till date I cannot directly modify /sys/class/backlight/%k/brightness and there seems to be a good reason behind it: /sys/class/backlight/%k is a symlink created and owned by root. So when you do chgrp on it, the link group does not change, but, the group of the link's target changes.

So in my case doing echo 100 > /sys/class/backlight/radeon_bl0/brightness gives permission error, where as echo 100 > /sys/devices/pci0000:00/0000:00:01.0/drm/card0/card0-eDP-1/radeon_bl0/brightness works like a charm!

from brightnessctl.

Is it still broken in brightnessctl in community?

from brightnessctl.

systemd-logind 243 (just around the corner now) will provide a dbus api for setting the brightness for the users seat.

from brightnessctl.

Is it still broken in brightnessctl in community?

@Hummer12007 yes.

from brightnessctl.

@jay-aye-see-kay right, I missed this step from the README. As the Arch package no longer set the binary as suid, but ships the udev rules, the user has to be in the video group as you mention.

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