screen brightness under lucid

[pkaplan1]

On Sunday, May 09, 2010 13:05 Reinhold Rumberger wrote:
> On Saturday 08 May 2010, pkaplan1 wrote:
> > On Friday, May 07, 2010 09:25 Reinhold Rumberger wrote:
> > > On Friday 07 May 2010, pkaplan1 wrote:
> > > > I'm running lucid on a Thinkpad T41.  Never had a display
> > > > problem until the new install.
> > > > 
> > > > As soon as I start KDE (not other WMs), the screen is dimmed
> > > > to about 50% of brightness.  I can brighten manually, but
> > > > it's a PITA.
> > > > 
> > > > Has anyone observed this or found a solution?
> > > 
> > > My Laptop does the same thing when on battery - that's how I set
> > > it up. Check your power management settings, they might be
> > > causing this.
> > 
> > I checked this.  PM is configured to set the screen to full
> > brightness when on AC power (as previously).  Changing these
> > settings didn't affect the behavior.
> > 
> > My original description is wrong, however.  The behavior affects
> > all window managers...whenever I start an X session, the screen
> > is dimmed to about 50%. Even switching between running WMs on
> > different virtual terminals causes the screen to dim to 50%.
> > Does this sound like a driver problem?  I'm running an ATI M7500
> > video card, but I didn't notice the behavior with the LiveCD??
> > Paul
> 
> My Dell's BIOS has an option for screen brightness that has a similar
> effect. It seems to confuse whatever is responsible for setting the
> screen's brightness. It seems that some sort of default brightness is
> stored at boot time and restored whenever the screen is switched back
> on. I haven't found a fix for this yet, and it hasn't bothered me
> enough to search particularly hard...
> 
>   --Reinhold

What kind of video card do you have, more precisely, which driver are you 
using.  I'm leaning towards a bug in the ati driver that plays badly with the 
lucid kernel.
Paul