Re: Problems with display power management
On Wed, Jul 27, 2005 at 09:12:41PM +0200, Thomas Halva Labella wrote:
> Hi again!
>
> I already posted something on this list, but I did not receive many
> answers. I hope to be luckier now:-)
I have the same problem. Different laptop, display and kernel.
In my case, Dell 8600, nvidia 4400go and the nvidia driver, WUXGA
display, woody, KDE 2.2.2, kernel 2.4.24.
> The short version of the problem is the following: when the screen of my
> laptop should switch off, instead of black it becomes white!
Unfortunately, no solution yet, but the few things I've tried lead me
to believe that what's happening is that the actual LCD is turning off
but the backlight remains on.
I have tried the KDE control center -> power control -> Energy.
When the "Power Off" setting is enabled, I see exactly this symptom
after the specified time.
I also see the same when I manually type:
xset dpms force off
It looks like the Power off timeout and the xset command both turn off
the actual display but don't affect the backlight.
Having read that the screensaver settings affect this, I have turned
off the screen saver, even though my screen saver was set to black
screen. No difference.
> A bit longer version: it is not 100 percent white, and the transition is
> not immediate. It starts getting brighter and brighter at the borders,
> and then it expands till the centre of the screen (it takes nearly one
> second to complete). It looks like it is burning, but the screen comes
> back as it was before as soon as I move the mouse or press a key.
Yes, same exact symptom.
>...
The question is (I think), how to turn off the backlight via software?
This might be an issue of bad firmware (Dell firmware is notoriously
linux-unfriendly, not to say buggy) and/or bad ACPI support in same,
in which case there might not be an easy solution. Anyone have a
non-firmware-patch fix for this?
Incidentally, Sarge on a Thinkpad 600E works perfectly in this respect.
The backlight goes off shortly after the display goes blank.
A.
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