Arch Linux

arenevier

Member

Registered: 2011-12-09

Posts: 5

brightness issue (when unplugging/plugging battery cable)

Hi,
on my laptop, when unplugging the battery cable, the screen becomes darker.
When plugging it back, the screen becomes brighter, but not as bright as from start.
To restore my previous brightness, I need to use xbacklight (or xrandr --brightness).
Even, xbacklight -get is enough to restore the correct brightness.

I don't have any of cpufrequtils, pm-utils, powernowd, laptop-mode-tools or any package to manage the power.

My video driver is intel (i915).

Do you have any idea of: what's causing the screen to change brightness when plugging/unplugging the battery ?
Why, after plugging the battery back, it doesn't restore its previous brightness until I try to get the brightness from the os ?

laloch

Member

Registered: 2010-02-04

Posts: 186

Re: brightness issue (when unplugging/plugging battery cable)

Hi, if you don't use any of the acpid, pm-utils, laptop-mode-tools, etc. "magic", it seems to be a BIOS feature. You may try to disable it via setup, or try to find a kernel module specific to your NB manufacturer/model (eg. dell-laptop) to override the ACPI BIOS.

Last edited by laloch (2011-12-09 14:12:08)

arenevier

Member

Registered: 2011-12-09

Posts: 5

Re: brightness issue (when unplugging/plugging battery cable)

Thanks for your reply. I could not disable anything in the bios. So, I installed acpid to run xbacklight when plugging the adapter on.

punkeroso

Member

From: Rome, Italy

Registered: 2007-01-19

Posts: 105

Re: brightness issue (when unplugging/plugging battery cable)

I would use this one https://bbs.archlinux.org/viewtopic.php?pid=1028685
Regards