fixbacklight.sh

#!/bin/bash
#
# Asus UX32VD acpi backlight fix
#
# Copyright(C) 2012 Eugen Dahm <eugen.dahm@gmail.com>.
#
# fix is based on a proposed bugfix posted on <https://bugs.freedesktop.org/show_bug.cgi?id=45452>
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

# Asus UX31A/32VD acpi backlight fix
# (Disclaimer!!!! not recommended to use if laptop is not the Asus UX32VD
# probably works with other models too, but the didl and cadl offset needs to be extracted
# from the dsdt)
# Update: Apparently works 1:1 on the Asus UX31A bios 2.06 without changes, IGDM base-address differs on previous bios version(v 2.04)
# will most certainly change with the next bios update, so beware
# Tested with bios 2.06

# IGDM_BASE has to be determined for each notebook model (except UX31A and UX32VD bios 2.06, address is already known on these models)
# IGDM is the operation region (\_SB_.PCI0.GFX0.IGDM) containing the CADL/DIDL fields
# \aslb is a named field containing the base-address of the IGDM region
# this address is influenced by the bios version, and maybe somehow by the installed ram (I don't know yet)
# how to get the address:
# - git clone git://github.com/Bumblebee-Project/acpi_call.git
# - make
# - load module with insmod or copy to /lib/modules/.... and modprobe
# - echo '\aslb' > /proc/acpi/call
# - cat /proc/acpi/call
# - this is the IGDM base address - fill in below

IGDM_BASE=0xBE8B7018
DIDL_OFFSET=0x120
CADL_OFFSET=0x160

#bios version check, change according to installed bios version
BIOS_VERSION="UX32VD.206"
#irrelevant for now
#TOTAL_MEMORY="9937592"
DMIDECODE_BIOS_VERSION="bios-version"

if [[ $EUID -ne 0 ]]; then
    echo "This script must be run as root" 1>&2
    exit -1
fi

# check for dmidecode
which dmidecode > /dev/null 2>&1
if [  $? -ne 0 ]; then
    echo "Error, dmidecode not found, please install it first" 2> /dev/stderr
    exit -1    
fi

function usage {
    echo "usage: ./fixbacklight.sh <start | shutdown>"
}

function bios_version_check {
    bios_version_found=$(dmidecode -s $DMIDECODE_BIOS_VERSION)
    test $bios_version_found != $BIOS_VERSION
    return $?
}

function memcheck {
    mem_found=$(grep -i memtotal /proc/meminfo  | cut -d ' ' -f 9)
    test $mem_found != $TOTAL_MEMORY
    return $?
}

if [  $# -ne 1 ]; then 
    usage
    exit -1
fi

# Bios Version guard, base-address is influenced by bios version
bios_version_check
if [ $? -ne 1 ]; then
    echo "Warning!!!, possible bug detected. Bios version does not match, please verify" > /dev/stderr
    exit -1
fi

# this didn't work as intended, and apparently the base address is the same on the ux31a and the ux32vd with bios 2.06
# until I determine, how the base-address is influenced by the installed ram (if at all), this check is disabled
#memcheck guard
#memcheck
#if [ $? -ne 1 ]; then
#    echo "Warning!!!, possible bug detected. Memory size doesn't match, found $mem_found kB, but expected $TOTAL_MEMORY kB" > /dev/stderr
#    exit -1
#fi

# check if IGDM_BASE is initialized
if [ -z $IGDM_BASE ]; then
    echo "IGDM_BASE not initialized. Please determine the IGDM base address, before you continue" > /dev/stderr
    exit -1
fi

# this basically copies the values of the initialized fields DIDL-DDL8 in the IGDM opregion and initializes CADL-CAL8 with it
# CADL-CAL8 are fields, telling the bios that a screen or something is connected (this is a bit speculation - check 
# <https://bugs.freedesktop.org/show_bug.cgi?id=45452> for more
# if interested, disasselbe the dsdt to understand, why no notifyevent gets thrown, when CADL isn't initialized 
# (hint: _Q0E/_Q0F are the backlight methods on the UX32VD)
action="$1"
if [ "$action" = "start" ] ; then
    dd if=/dev/mem skip=$(( $IGDM_BASE + $DIDL_OFFSET )) of=/dev/mem seek=$(( $IGDM_BASE + $CADL_OFFSET )) count=32 bs=1 > /dev/null 2>&1
    status=$?
    if [ $status -eq 0 ]; then
	echo "CADL region successfully initialized"
	exit 0
    fi
elif [ "$action" = "shutdown" ]; then
    perl -e 'print "\x00"x32' | dd of=/dev/mem bs=1 seek=$(( $IGDM_BASE + $CADL_OFFSET )) count=32 > /dev/null 2>&1
    status=$?
    if [ $status -eq 0 ]; then
	echo "CADL region successfully prepared for shutdown"
	exit 0
    fi
else
    echo "action $action unknown" > /dev/stderr
    usage
    exit -1
fi

if [ $status -ne 0 ]; then
    echo "Error!!, couldn't initialize CADL"
    exit -1
fi