Comment 129 for bug 1098216

well, I guess the problem also exists in 3.3 kernel, right?

it seems that this patch introduces the "regression".
commit fba4e087361605d1eed63343bb08811f097c83ee
Author: Igor Murzov <email address hidden>
Date: Sat Oct 13 04:41:25 2012 +0400

    ACPI video: Ignore errors after _DOD evaluation.

    There are systems where video module known to work fine regardless
    of broken _DOD and ignoring returned value here doesn't cause
    any issues later. This should fix brightness controls on some laptops.

    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47861

    Signed-off-by: Igor Murzov <email address hidden>
    Reviewed-by: Sergey V <email address hidden>
    Signed-off-by: Zhang Rui <email address hidden>

But IMO, the ACPI backlight control on your laptop is always broken,
but this commit
commit ea9f8856bd6d4ed45885b06a338f7362cd6c60e5
Author: Igor Murzov <email address hidden>
Date: Fri Mar 30 21:32:08 2012 +0400

    ACPI video: Harden video bus adding.

    It is always better to check return values, so add some new checks and
    correct existing ones.

    v2: Be consistent and don't mix errors from -E* and AE_* namespaces.

    Signed-off-by: Igor Murzov <email address hidden>
    Signed-off-by: Len Brown <email address hidden>
happens to make your laptop stop using ACPI backlight control. :)

can you please attach the dmidecode output of your laptop?
so that I can backlist your laptop from ACPI Backlight control.