From: Aaron Lu Date: Wed, 6 Nov 2013 01:07:10 +0000 (+0800) Subject: ACPI / video: Quirk initial backlight level 0 X-Git-Tag: v3.13-rc1~96^2~8^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2c62333a408f;p=pandora-kernel.git ACPI / video: Quirk initial backlight level 0 Some firmware doesn't initialize initial backlight level to a proper value and _BQC will return 0 on first time evaluation. We used to be able to detect such incorrect value with our code logic, as value 0 normally isn't a valid value in _BCL. But with the introduction of Win8, firmware begins to fill _BCL with values from 0 to 100, now 0 becomes a valid value but that value will make user's screen black. This patch test initial _BQC for value 0, if such a value is returned, do not use it. References: https://bugzilla.kernel.org/show_bug.cgi?id=64031 References: https://bugzilla.kernel.org/show_bug.cgi?id=61231 References: https://bugzilla.kernel.org/show_bug.cgi?id=63111 Reported-by: Qingshuai Tian Tested-by: Aaron Lu # on "Idealpad u330p" Reported-and-tested-by: # on "Acer Aspire V5-573G" Reported-and-tested-by: Kirill Tkhai # on "HP 250 G1" Signed-off-by: Aaron Lu Cc: All applicable Signed-off-by: Rafael J. Wysocki --- Reading git-diff-tree failed