Some workarounds to adjust the backlight brightness using the function left/right keys on my Acer laptop.
Currently using elementaryOS, based on Ubuntu LTS(12.04).
You can fix the issue by editing /etc/default/grub and adding:
acpi_osi=Linux acpi_backlight=vendor
to
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash
resulting in:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor
Then, save and close the /etc/default/grub file and update the grub:
sudo update-grub
What you can do is to use a manual override that , by modifying /etc/rc.local as follows:
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits(chmod).
#
# By default this script does nothing.
echo 978 > /sys/class/backlight/intel_backlight/brightness
chmod 777 /sys/class/backlight/intel_backlight/brightness
exit 0The downside is that you can't change the brightness easily except by manually modifying the file /sys/class/backlight/intel_backlight/brightness
What do?
Use the brightchg.sh script to map the function keys and change programmatically the brightness of the screen, using custom keys on your keyboard.
#!/bin/bash
# Acer Travelmate P253-M brightness control workaround
# Note: add the following to /etc/rc.local
# chmod 777 /sys/class/backlight/intel_backlight/brightness
# For convenience, assign whatever keys you want to run this script
# Fine tune the bump parameter as required
#
#488 Lowest with backlight on
#976
#1464
#1952
#2440
#2928
#3416
#3904
#4392
#4880 Brightest
#
# Usage:
# ./brightchg.sh up # bump up brightness
# ./brightchg.sh down # bump down brightness
#
curr=`cat /sys/class/backlight/intel_backlight/brightness`
bump=244
if [ "$1" == "up" ]; then
curr=`echo "$curr + $bump" | bc`
else
curr=`echo "$curr - $bump" | bc`
fi
echo $curr | tee /sys/class/backlight/intel_backlight/brightness