I would expect them to mean
BATT_BRIGHTNESS_COMMAND whenever you're on battery
LM_AC_BRIGHTNESS_COMMAND on ac and laptop mode
NOLM_AC_BRIGHTNESS_COMMAND on ac and no laptop mode
the value is the number that controls the brightness
BRIGHTNESS_OUTPUT is /sys/class/backlight/intel_backlight/brightness
So, the brightness will still change but you can control to what it changes.
On my laptop I cannot change brightness in software at all. The hardware
remembers 2 values for brightness, one for ac and one for battery... You
might want to check if there is some setting in BIOS, probably not.
And if you really want to go overboard, you could write a silly little script
that would copy the current value of brightness somewhere every minute or so
and then would set the new brightness to that whenever there is ac/battery
change. Of course any brightness changes within the last minute would be
lost. There wouldn't happen to be such a file already, like
previous_brightness in the folder? :)
Or then you could try to see if you can catch the change when it happens by
putting a very early and a very late script to power.d to see if they see
different values, then you wouldn't need such a silly polling script and
wouldn't have such a bad 1 minute retention. Donät expect this to work
though but could be worth trying.
