ACPI video: support _BCL packages that don't export brightness levels when machine is on AC/Battery

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Many buggy BIOSes don't export the brightness levels when machine
is on AC/Battery in the _BCL method.

Reformat the _BCL package for these laptops:
now the elements in device->brightness->levels[] are like:
levels[0]: brightness level when on AC power.
levels[1]: brightness level when on Battery power.
levels[2]: supported brightness level 1.
levels[3]: supported brightness level 2.
...
levels[n]: supported brightness level n-1.
levels[n + 1]: supported brightness level n.
So if there are n supported brightness levels on this laptop,
we will have n+2 entries in device->brightnes->levels[].

level[0] and level[1] are invalid on the laptops that don't
export the brightness levels on AC/Battery.
Fortunately, we never use these two values at all, even for the
valid ones.

http://bugzilla.kernel.org/show_bug.cgi?id=12249

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Matthew Garrett <mjg59@srcf.ucam.org>
Acked-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

...

This commit is contained in:

Zhang Rui 2009-03-18 16:27:12 +08:00 • committed by Len Brown

parent 24450c7add

commit d32f69470c

1 changed files with 30 additions and 7 deletions

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37

drivers/acpi/video.c

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