Comment 4 for bug 1133168

We probably need this patch to fix the issue.
I have submitted this patch for SRU ago, but it will bring a pre-existing bug to light, so the kernel team reject it.
I'll re-verify this patch now and re-send the SRU request.

commit d627b62ff8d4d36761adbcd90ff143d79c94ab22
Author: Lekensteyn <email address hidden>
Date: Tue Jun 26 00:36:24 2012 +0200

    i915: initialize CADL in opregion

    This is rather a hack to fix brightness hotkeys on a Clevo laptop. CADL is not
    used anywhere in the driver code at the moment, but it could be used in BIOS as
    is the case with the Clevo laptop.

    The Clevo B7130 requires the CADL field to contain at least the ID of
    the LCD device. If this field is empty, the ACPI methods that are called
    on pressing brightness / display switching hotkeys will not trigger a
    notification. As a result, it appears as no hotkey has been pressed.

    Reference: https://bugs.freedesktop.org/show_bug.cgi?id=45452
    Tested-by: Peter Wu <email address hidden>
    Signed-off-by: Peter Wu <email address hidden>
    Acked-by: Jesse Barnes <email address hidden>
    Signed-off-by: Daniel Vetter <email address hidden>