I have two displays. I can successfully set brightness for the first display using e.g.
xbacklight -set 30, but I cannot dim my second display connected to HDMI. I tried
xbacklight -display HDMI1 -set 30, and
xbacklight -display 1 -set 30, but I've got
RANDR Query Version returned error -1 in both cases.
What do I have to write as the -display parameter?
xrandr --listmonitors Monitors: 1 0: +*HDMI1 1920/527x1080/296+0+0 HDMI1
The following command works perfectly:
xrandr --output HDMI1 --brightness 0.3