After trying several patches, possibly all wrong I have come to the conclusion that it is not possible to get brightness control working on this laptop or I am on the wrong track. Another possibility is that I have no expertise to solve this problem.
So far the patches I tried were all done in the DSDT, but shouldn't they be done to SSDT-2? Because there I find PEGP.DGFX, BCM, BQL and BCL and LCD. IF so, can anyone of you analyse this SSDT-2 an possibly patch it?
ACPI.zip