Arch Linux

e-dard

Member

Registered: 2008-10-25

Posts: 3

LCD Panel not supported (acpi brightness)

Hi all,

This is my first post, Hello!  I have used several distros but this is my first time using Arch.

I have a dell d420 (dual core / intel graphics).  I have installed Arch with lxde / compiz.

Things have been going pretty well so far, I really like the distro.  However, I am having problems with laptop-tools and adjusting the brightness of my lcd on AC acpi events.

Basically, I have /etc/laptop-mode/conf.d/lcd-brightness.conf configured as follows:

#
# Should laptop mode tools control LCD brightness?
#
CONTROL_BRIGHTNESS=1


#
# Commands to execute to set the brightness on your LCD
#
BATT_BRIGHTNESS_COMMAND="echo 20"
LM_AC_BRIGHTNESS_COMMAND="echo 70"
NOLM_AC_BRIGHTNESS_COMMAND="echo 100"
BRIGHTNESS_OUTPUT="/proc/acpi/video/VID/LCD/brightness"

Further, laptop-mode is running and set up as a daemon.

The problem is when I plug/unplug the power cable the brightness of the panel does not change in the way I would expect it to.  Sometimes it does not change at all, sometimes it gets brighter on battery than it does on AC!!!  The brightness keys on my laptop work fine (however, they are I believe prgrammed into the bios and rely on no software to adjust the panel.)

Things I have installed / setup:

acpid
acpi
laptop-tools

I have noticed that there seems to be a problem recognising my panel, when I do a

cat /proc/acpi/video/VID/LCD/brightness

I get the response:

<not supported>

Also:

cat /proc/acpi/video/VID/LCD/info 
device_id:    0x0400
type:         UNKNOWN
known by bios: no

I think this is the problem, as laptop-tools and acpi seem to be configured correclty apart from this issue.  Any thoughts?

Many, thanks.

Last edited by e-dard (2008-10-25 16:11:37)