How to modify the scale attribute of a backlight in sysfs?

How can a user change the scale attribute of a backlight that is exposed in sysfs? On my machine it's located at /sys/class/backlight/amdgpu_bl1/scale. I tried using udev to add write permissions to the file and write to it, but that doesn't change it from unknown. Running udevadm test /sys/class/backlight/amdgpu_bl1 returns:

amdgpu_bl1: /etc/udev/rules.d/90-backlight-scale.rules:5 RUN '/bin/chmod a+w /sys/class/backlight/amdgpu_bl1/scale'
amdgpu_bl1: /etc/udev/rules.d/91-backlight-scale.rules:5 RUN '/bin/echo non-linear > /sys/class/backlight/amdgpu_bl1/scale'
amdgpu_bl1: /usr/lib/udev/rules.d/99-systemd.rules:74 Skipping builtin 'path_id' in IMPORT key
amdgpu_bl1: Failed to update tags under /run/udev/tag/: Permission denied

After running the udev scripts, the file properties are

-rw-rw-rw-. 1 root root 4096 Mar 21 08:08 scale

Trying to write to it with echo non-linear | sudo tee /sys/class/backlight/amdgpu_bl1/scale yields

tee: /sys/class/backlight/amdgpu_bl1/scale: Input/output error

Is modifying /sys/class/backlight/amdgpu_bl1/scale at all possible?