The ACPI scripts merely fake the keys when called, with a hard coded value. This, obviously, was not working.
So, I decided on a rather convoluted method. First, I ended up finding my actual brightness control device (there are several listed on my machine), by running the following as root (it will NOT work via sudo):
%for n in /proc/acpi/video/**/LCD/brightness; do \ echo "Trying $n..."; for fade in `seq 1 100`; do sleep \ 0.01s; echo -n "$fade" > $n; done; done
This will print the devices it finds, and attempt to set the LCD levels from 1 (nearly off) to 100 (full brightness). As different LCDs have different specifications, you can't just randomly assume a single number will work. I was being lazy, and although it didn't accept them all, it was still a neat effect.
I found that my LCD device was actually: /proc/acpi/video/VID1/LCD/brightness
Then, I made the world's ugliest parser to see what the available levels were, and to shift up, or down, according to the script. Since there are separate 'up' and 'down' scripts, I decided to be lazy. Have I mentioned yet how incredibly ugly this whole thing is? I wish there was a more bourne-ish portable way to deal with quasi-arrays.
Here's my new /etc/acpi/video_brightnessdown.sh:
#!/bin/sh
#Yeah, I got kind of lazy. Arrays in Bourne SUCK.
DEVICE=/proc/acpi/video/VID1/LCD/brightness
#. /usr/share/acpi-support/key-constants
#acpi_fakekey $KEY_BRIGHTNESSDOWN
CURRENTLEVEL=`grep 'current:' $DEVICE | awk '{print $2}'`
if [ "x"$CURRENTLEVEL = "x0" ]; then
CURRENTLEVEL=100
fi
SORTEDLEVELS=`grep 'levels:' $DEVICE | sed -e \
s,levels:,,g -e 's,\s,\n,g' | sort -n | uniq | \
grep -v '^$' | sed s,\n,\ ,g | xargs echo`
for levels in `echo $SORTEDLEVELS | sed 's,\n,\ ,g'`
do
if [ $CURRENTLEVEL = $levels ]; then
echo -n $LASTLEVEL > $DEVICE
break
fi
LASTLEVEL=$levels
done
... and /etc/acpi/video_brightnessup.sh:#!/bin/sh
#. /usr/share/acpi-support/key-constants
#acpi_fakekey $KEY_BRIGHTNESSUP
DEVICE=/proc/acpi/video/VID1/LCD/brightness
CURRENTLEVEL=`grep 'current:' $DEVICE | awk '{print $2}'`
if [ "x"$CURRENTLEVEL = "x0" ]; then
CURRENTLEVEL=100
fi
SORTEDLEVELS=`grep 'levels:' $DEVICE | sed -e s,levels:,,g \
-e 's,\s,\n,g' | sort -n -r | uniq | grep -v '^$' \
| sed s,\n,\ ,g | xargs echo`
for levels in `echo $SORTEDLEVELS | sed 's,\n,\ ,g'`
do
if [ $CURRENTLEVEL = $levels ]; then
echo -n $LASTLEVEL > $DEVICE
break
fi
LASTLEVEL=$levels
doneRemember to chmod your files, and chown them!
chmod 755 /etc/acpi/video_brightnessup.sh chmod 755 /etc/acpi/video_brightnessdown.sh chown root.root /etc/acpi/video_brightnessup.sh chown root.root /etc/acpi/video_brightnessdown.shI hope these scripts work for you, and save you some of the headache I was experiencing!
