Re: [PATCH] ACPI: disable the ACPI backlight control on laptops with buggy _BCL methods

Matthew Garrett
2009-01-09T01:18:15Z

On Fri, Jan 09, 2009 at 09:13:38AM +0800, Zhang Rui wrote:

>
> _BQC returns 3 when the actual backlight level is 0x50.
> We only know that the value returned by _BQC is invalid but we never
> know the value is an index until we see the _AML code.

If the value returned is less than the smallest value in the _BLC block,
then it's an index. This heuristic will never break a standards
compliant system, but (to the best of my knowledge) will work with any
of these systems that we're currently aware of.

--
Matthew Garrett | mjg59@srcf.ucam.org