Duplicate ACPI video bus devices for the same VGA controller

[AceLan Kao]

There is no /sys/class/backlight/acpi_video0 if there are suplicate ACPI video bus devices declared in the BIOS

From linus' tree, the issue can be fixed by this commit and verified by me.

commit 86ed4bc83abf530cf2019044b74f89a39dfd6425
Author: Bob Moore <email address hidden>
Date: Thu May 3 11:08:19 2012 +0800

    ACPICA: Add support for multiple notify handlers

    This change adds support to allow multiple notify handlers on
    Device, ThermalZone, and Processor objects. Also re-worked
    and restructured the entire notify support code for handler
    installation, handler removal, notify event queuing, and notify
    dispatch to handler.

    Extends and updates original commit 3f0be67("ACPI / ACPICA: Multiple
    system notify handlers per device") by Rafael Wysocki.

    Signed-off-by: Bob Moore <email address hidden>
    Signed-off-by: Lin Ming <email address hidden>
    Signed-off-by: Len Brown <email address hidden>

[Anthony Wong (anthonywong)]

http://ubuntu.5.x6.nabble.com/Quantal-SRU-Fixed-the-duplicated-ACPI-video-devices-issue-td5017193.html

Close bug as Acelan mentioned v3.6-rc1 can fix the bug in the email thread.