From: Zhang Rui <rui.zhang@intel.com>
Date: Wed, 30 Dec 2009 07:59:23 +0000 (+0800)
Subject: ACPI video: Prune dupe video devices, unless "video.allow_duplicates"
X-Git-Tag: v2.6.33-rc5~9^2~8^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c504f8cb68eb0d6cde53ba043daff8cb34586493;p=pandora-kernel.git

ACPI video: Prune dupe video devices, unless "video.allow_duplicates"

Some buggy BIOS exports multiple ACPI video bus devices for the same
VGA controller, and multiple backlight control methods as well.
This messes up the ACPI video backlight control.

http://bugzilla.kernel.org/show_bug.cgi?id=13577

With this patch applied, only the FIRST ACPI video bus device
under a PCI device node is bind to ACPI video driver by default.

If the first ACPI video bus device doesn't work well, we can use
video.allow_duplicates=1 to go back to the old behavior.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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