Comment 24 for bug 1686268

> 1. the grep . /var/lib/systemd/backlight/* shows the value of the brightness that was right before the last reboot. That doesn't change real-time when I change the brightness with the slider. The value appear to get stored right before the reboot.

Yes, the service will restore brightness value at boot, and store brightness value at shutdown stage. It does not save the brightness at realtime.

> 2. the cat /sys/class/backlight/intel_backlight/brightness shows whatever is the current value of the brigtness and is stored/updated real-time, as soon as I change it with the slider or the hardware key

Yes. that's correct.

Systemd saves the brightness before shutdown, then restore it after boot.
It doesn't save brightness in real-time.

So, wrt comment #20, did you change brightness in anyway?