Bug#510277: linux-image-2.6.26-1-amd64: Dims screen when power is removed so much that the screen is not usable
On Wed, 2008-12-31 at 18:31 +0100, Bastian Blank wrote:
> tags 510277 moreinfo
> thanks
>
> On Wed, Dec 31, 2008 at 01:04:01AM +0000, Sam Morris wrote:
> > When I run my Samsung Q45 laptop on battery power, the screen is dimmed to
> > save power. This is fine, except that it is dimmed too much--the screen becomes
> > so dark that it is basically unusable if there are any external sources of
> > light (the sun, or room lighting when it's night time).
>
> The dimming is not done by the kernel itself. Either ACPI or a userspace
> tool is responsible, gnome-power-manager for example.
I just checked and the dimming occurs before I've booted the OS. I found
a BIOS option that disables this stupid behaviour. Sorry for the noise!
> > The dimming happens in a weird way--it seems to redefine the value of 100%
> > brightness, as if I run 'xbacklight --get' while the screen is dark, it still
> > returns '100'.
>
> I don't know what xbacklight is, but the kernel controls are exported in
> the sysfs as /sys/class/backlight. Please check the contents of this.
FYI, xbacklight sets the backlight via the X11 RANDR protocol extension.
/sys/class/backlight is empty on this machine.
>
> Bastian
>
--
Sam Morris <sam@robots.org.uk>
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