Comment 5 for bug 631412

This bug is likely to be not fixed anytime soon.

https://bugzilla.kernel.org/show_bug.cgi?id=14216

Comment #43 From Zhang Rui 2010-09-27 01:18:54

we have several bug reports that ACPI video driver controls the backlight
correctly, but the backlight fails to change after evaluating the AML code.
We have no idea what is going wrong here, and how to fix it.
A alternative way is to disable ACPI video driver and control the backlight in
other ways, like, platform specific control methods, the legacy PCI register,
etc.