Bug#651741: gnome-power-manager: display backlight brightness has no effect on Sony Vaio VPCYA1V9E

[littlebat <dashing.meng@gmail.com>]

Hi,

I think I found a easy and least effect to the existed things' way for adjusting intel_backlight using udev rules.

I noticed "change" action of "backlight" subsystem when I press Fn + PgUp/PgDn on my lenovo G360 + 3.2 Kernel notebook. So I wrote a rules of "/etc/udev/rules.d/99-writeintelbacklight.rules" as below:

    ACTION="" SUBSYSTEM=="backlight", RUN+="/usr/sbin/writeintelbacklight.sh"

A shell: "/usr/sbin/writeintelbacklight.sh"

    #!/bin/bash

    

    intelmaxbrightness=`cat /sys/class/backlight/intel_backlight/max_brightness`

    acpimaxbrightness=`cat /sys/class/backlight/acpi_video0/max_brightness`

    scale=`expr $intelmaxbrightness / $acpimaxbrightness`

    acpibrightness=`cat /sys/class/backlight/acpi_video0/brightness`

    newintelbrightness=`expr $acpibrightness \* $scale`

    curintelbrightness=`cat /sys/class/backlight/intel_backlight/actual_brightness`

    if [ "$newintelbrightness" -ne "$curintelbrightness" ]

    then

      echo $newintelbrightness > /sys/class/backlight/intel_backlight/brightness

    fi

    exit 0

Of course, you need do a "sudo chmod +x /usr/sbin/writeintelbacklight.sh