Re: [PATCH v2] platform/x86: Add driver for Apple gmux device

[Seth Forshee <seth.forshee@canonical.com>]

On Mon, Mar 12, 2012 at 02:21:26PM +0000, Matthew Garrett wrote:
> apple_bl probably needs some matching work to disable itself if there's 
> a gmux present? Otherwise, this looks good.

How do you suggest doing this? The tricky point is that the gmux object
can be present in ACPI when the gmux hardware isn't really present
(which is what the version check really does, verifies the hardware is
actually there). So apple_bl can't just look for the ACPI object; it
needs to either communicate with apple-gmux or duplicate some of its
logic.

We also have the problem of gmux_backlight versus acpi_video. On most
machines with a gmux the acpi_video backlight interface is present but
just doesn't work. This problem isn't just limited to Apples. I'm of the
opinion that we need a more generalized solution for arbitrating between
the backlight interfaces present on a given machine, but I haven't had a
chance to really think about what that would look like.

Seth