Finally the day came when all the clean installs in the world will not make Vista any faster on my old Samsung R60 (1.5 Ghz Dualcore), so I figured it’s time for a Linux distro. Apart from high power consumption (it’s a known bug [1]) nearly everything worked as expected, left two things: I wasn’t able to use the Fn keys to change the screen brightness.
Three reasons for that:
1. Ubuntu expects the screen brightness device to reside in /proc/acpi/video/VGA/LCD/brightness while for the particular device it will be in /proc/acpi/video/ATIM/LCD/brightness
2. The device is setup by default as read-only
3. The device will not allow the standard brightness parameters
The solution consists in the following steps:
1. copy video_brightnessdown.sh and video_brightnessup.sh to /etc/acpi
2. make those files executable:
sudo chmod a+x /etc/acpi/video_brightnessdown.sh sudo chmod a+x /etc/acpi/video_brightnessup.sh
3. add key shortcuts to those files (System->Preferences->Keyboard shortcuts)
4. setup a startup script (i.e. in /etc/init.d and link from the appropriate rc.d to it) that makes the device writeable:
#!/bin/bash
BRDEV=/proc/acpi/video/ATIM/LCD/brightness
chmod a+w $BRDEV
video_brightnessdown.sh
#!/bin/bash
BRDEV=/proc/acpi/video/ATIM/LCD/brightness
chmod a+w $BRDEV
CURRENT=$(grep "current:" $BRDEV |awk '{print $2}')
case "$CURRENT" in
100)
echo -n 80 > $BRDEV;
;;
80)
echo -n 70 > $BRDEV;
;;
70)
echo -n 60 > $BRDEV;
;;
60)
echo -n 50 > $BRDEV;
;;
50)
echo -n 40 > $BRDEV;
;;
40)
echo -n 30 > $BRDEV;
;;
30)
echo -n 10 > $BRDEV;
;;
*)
echo -n 10 > $BRDEV ;
;;
esac
video_brightnessup.sh
#!/bin/bash
BRDEV=/proc/acpi/video/ATIM/LCD/brightness
chmod a+w $BRDEV
CURRENT=$(grep "current:" $BRDEV |awk '{print $2}')
case "$CURRENT" in
100)
echo -n 100 > $BRDEV;
;;
80)
echo -n 100 > $BRDEV;
;;
70)
echo -n 80 > $BRDEV;
;;
60)
echo -n 70 > $BRDEV;
;;
50)
echo -n 60 > $BRDEV;
;;
40)
echo -n 50 > $BRDEV;
;;
30)
echo -n 40 > $BRDEV;
;;
10)
echo -n 30 > $BRDEV;
;;
*)
echo -n 100 > $BRDEV ;
;;
esac
George's Techblog 