I'm trying to find out how to power off the backlight in a device I'm using with a built-in screen.
I believe that DPMS works with the screen, but X is not installed, so I can't use
xset. I thought the non-X11 alternative was
setterm and I've tried (as root) the following:
setterm -powersave powerdown > /dev/tty1
to set the DPMS state when the screen is blanked. However, I get the following error:
setterm: cannot (un)set powersave mode: Invalid argument
I get a similar error on other Ubuntu installs on different hardware and for any variation on the
-powersave options listed in
Why am I getting this error? Is there another (non-X11) way to send DPMS commands to the hardware?
The device is an O2 Joggler (based on the OpenPeak OpenFrame 7) which has an i386 architecture (Intel Atom). I'm running a slightly modified community-supplied version of 12.04.02 server.
This modified version comes with a driver which provides
sysfs screen control, including a writeable psuedo-file to supposedly switch off the backlight, but you can still see it glowing in a darkened room. I'm hoping there will be a way to power it down completely.