On Wed, May 17, 2017 at 8:48 AM, Lars Noodén <lars.nooden@???> wrote:

> On 05/04/2017 03:42 PM, Lars Noodén wrote:
> > I'm having trouble adjusting the backlight on my LCD screen in RC 1 with
> > XFCE4. No matter what I've tried so far, it stays where it is. With
> > Ubuntu 16.04, things are pre-configured and it is just a matter of
> > pressing the right function buttons. However, with Devuan Jessie RC 1
> > the right commands are hard to figure out.
> >
> > Here is what I've tried so far to change the backlight intensity. None
> > have any effect:
> >
> > $ xrandr --output default --brightness 0
> > xrandr: Gamma size is 0.
>

I did this just yesterday on a laptop running Funtoo with Fluxbox, where
the built-in function keys for dimming did not work. But I specified a
decimal, like this:

xrandr --output default --brightness .7

That worked for me. Maybe the problem is that you specified zero for the
brightness.