display power management and white out

[Peter Arremann]

On Tuesday 05 April 2005 18:17, E GCP wrote:
> Hi!
>
> It seems that the latest updates of xorg (FC3) created a problem with the
> display power management in Gnome. When enabled the power management is
> supposed to power down the monitor (in my case LCD of laptop) , so it will
> turn black (no power). However, now instead of that, it goes white. When
> the time to standby, or suspend, or off is reached the LCD screen goes
> white instead a black. Any ideas? Does anybody has this problem? This only
> happened after I installed the latest xorg updates
> (xorg-x11-6.8.2-1.FC3.13).
What do you mean with white? A nice clean white or is it a matte white glow of 
the backlight without the LCD displaying a picture? Does "xset dpms force 
off" yield the same result?

If you're running a NVidia based card the later behavior seems to be normal 
for the stock nv driver. the commercial nvidia driver does turn off the 
backlight. There is a number of bug reports in the xorg bug tracker, one of 
them including a patch for 6.8 that has never been incorporated into the main 
xorg stuff. Many of them have been there for over a year 
(http://bugs.xfree86.org/show_bug.cgi?id=1196 as just one example, search 
bugzilla for nvidia+backlight for the rest of them) and no one seems to 
bother with it... 
If that's your issue and you're running the commercial drivers, depending on 
your environment, it will automatically work correctly - if not, just key off 
the acpi event of the lid and run a script that forces the backlight off. 
The second is a hack cause it requires the Xauth of the logged in user - I 
hardcoded it for my setup but it's easy to make generic (just check who is 
logged in and go from there). 

$ cat /etc/acpi/events/lid.con
event=button/lid.*
action=/usr/local/bin/lidaction 
$ cat /usr/local/bin/lidaction
#!/bin/bash
export XAUTHORITY=/home/loony/.Xauthority
export DISPLAY=:0

grep open /proc/acpi/button/lid/LID/state  >> /dev/null
if [ $? -eq 0 ] ; then
        xset dpms force on >> /dev/null
else
        xset dpms force off >> /dev/null
fi

Peter.