[Karmic] SRU: Enable backlight control on certain laptops

Stefan Bader stefan.bader at canonical.com
Mon Aug 31 13:55:59 UTC 2009


SRU justification:

Impact: Same problem as for current Jaunty: acpi checks for video devices by 
looking for certain methods but some broken BIOSes only define a subset of 
this. Some even do this only for a few of the multiple definitions (one is 
there for each potential hardware variation), so those machines had backlight 
control before Linux verified the PCI ID to be present.

Fix: The following patch was sent upstream and ACKed, but not yet pulled into 
the kernel. Likely this takes until 2.6.32.

Testcase: Tested by the reporters against a patched Jaunty kernel. Without the 
changes there is no backlight control. With it there is.


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