Backlight problems

[Xandros Pilosa]

Dne 03.02.2010 (sre) ob 10:41 +0000 je Ken zapisal(a):
> Well, I guess something changed on my system and now I have a bit of a 
> problem.  The backlight on my laptop seems to turn off randomly and 
> refuse to turn back on.  Luckily I can work with it with the attached 
> monitor.  

Hello,
it would be helpful, if you can provide more details about your system -
which version, which laptop, graphic card at least.

[snip]

> Now, the command, 
> 
> xset dpms force on
> 
> does absolutely nothing. 

You may consider to use vbetool to test ("dpms off" and "dpms on" -
refer to man pages about it).

> 
> So this looks like some kind of a software problem.  Something on my 
> system is deciding that it is time to turn off the backlight.  How do I 
> determine what it is?  Is there a way I can force the system to ignore 
> these requests?  
> 
Providing that you are using gnome: gnome-screensaver or
gnome-power-manager most probably.
You can try first to disable screen saver (if you have selected
blank-only option) and power management regarding screen in System -->
Settings.
If that doesn't help, you can disable dpms or ambient sensors (just a
guess) altogether with gconf-editor in:
/apps/gnome-power-manager/backlight
and
/apps/gnome-power-manager/ambient.
But this is just an ugly workaround. It would be more useful to know
why / when (update of graphic card driver maybe) this started to
happened, so you may consider to search through bug reports in
bugs.launchpad.net, if there are similar reports.
Anyway, I hope it helps a bit.
Regards