Thomas,
The attached script does that.
The kernel backlight devices are not so new. They are used to blank
backlights in framebuffer mode when DPMS doesn't work. Currently there
is only support for some exotic PDA backlights.
But I thought of the same to port the mactel-linux backlight tool to
such an in-kernel backlight driver. This has the obvious advantage that
you get a device file for which you can set propper permissions with
udev instead of the suid binary that we have now! Anybody up to writing
the driver?
Odi
Thomas Meyer wrote:
> Hi.
>
> Is there a daemon, that polls the current ambient light sensor values
> (someone should create an ambient light device class...) and sets the
> keyboard light value (led class devices) and the led panel backlight
> (totaly new, current linus-git-tree; backlight class devices)
> automatically?
>
> With kind regards Thomas
#!/bin/sh
# Keyboard backlight control for my MacBook Pro
# (C) 2006 by Ortwin Glück
#
# external config: all values 0-255
# kbd light off above this much ambient light
LIGHT_LEVEL=160
# brightest kbd light below this little ambient light
DARK_LEVEL=30
# kbd no brigther than this
MAX_BRIGHT=255
# kdb no lower than this
MIN_BRIGHT=80
# devices
BRIGHT="/sys/bus/platform/devices/applesmc/leds:smc:kbd_backlight/brightness"
LIGHT="/sys/bus/platform/devices/applesmc/light"
# speed when adjusting kdb light
SHORT_SLEEP=0.1
# reaction time
NORMAL_SLEEP=1
# reads the max ambient light from the two sensors
ambient_light() {
local s=$(cat ${LIGHT})
if [[ $s =~ "([[:digit:]]+),([[:digit:]]+)" ]]; then
local a=${BASH_REMATCH[1]}
local b=${BASH_REMATCH[2]}
if [ $a -gt $b ]; then
light=$a
else
light=$b
fi
else
echo "unexpected value: $s"
light=$LIGHT_LEVEL
fi
}
# calculates the target brightness level (with cutoff)
calc_bright() {
if [ $light -lt $LIGHT_LEVEL ]; then
local lpct=$((100 * ($light - $DARK_LEVEL) / ($LIGHT_LEVEL -
$DARK_LEVEL)))
[ $lpct -gt 0 ] || lpct=0
bright=$((($MIN_BRIGHT + ($MAX_BRIGHT - $MIN_BRIGHT) * (100 -
$lpct)) / 100))
else
bright=0
fi
}
# adjusts brightness towards target
# returns 0 when target reached
adj_bright() {
local cb=$(cat ${BRIGHT})
local dist=$(($cb - $bright))
if [ $dist -gt 0 ]; then
[ $dist -gt 5 ] || return 0
let cb-=5
else
[ $dist -lt -5 ] || return 0
let cb+=5
fi
#echo "l: $light, kbd: $cb -> $bright"
echo "$cb" > $BRIGHT
return 1
}
renice 19 -p $$ >/dev/null 2>&1
# adjustment loop
while [ 1 ]; do
ambient_light
calc_bright
adj_bright
if [ $? ]; then
sleep 0.1
else
sleep 1
fi
done
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