diff options
| author | Aaron Lu <aaron.lu@intel.com> | 2013-11-06 09:07:10 +0800 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-11-07 02:14:48 +0100 |
| commit | 2c62333a408f5badd2d2ffd7177f95deeccc5ca4 (patch) | |
| tree | ca900a9a138898d7d499341eac6bb35d07572c40 /drivers/acpi/video.c | |
| parent | 9efa5e50598c5568b0678bb411b239a0b6e9a328 (diff) | |
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 <qingshuai.tian@intel.com>
Tested-by: Aaron Lu <aaron.lu@intel.com> # on "Idealpad u330p"
Reported-and-tested-by: <erno@iki.fi> # on "Acer Aspire V5-573G"
Reported-and-tested-by: Kirill Tkhai <tkhai@yandex.ru> # on "HP 250 G1"
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/video.c')
| -rw-r--r-- | drivers/acpi/video.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c index bf521b36c2f9..a049fa9360d0 100644 --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -858,7 +858,7 @@ acpi_video_init_brightness(struct acpi_video_device *device) for (i = 2; i < br->count; i++) if (level == br->levels[i]) break; - if (i == br->count) + if (i == br->count || !level) level = max_level; } |