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ACPI video: introduce module parameter video.use_bios_initial_backlight

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Introduce module parameter video.use_bios_initial_backlight.

Some BIOSes claim they use the minimum backlight at boot,
and this may bring dimming screen after boot.
https://bugzilla.kernel.org/show_bug.cgi?id=21212

use video.use_bios_initl_backlight=0 to use
the maximum backlight level after boot.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Zhang Rui 2010-12-06 15:04:27 +08:00 committed by Len Brown
parent cf7d7e5a19
commit 99fd1895ef
1 changed files with 12 additions and 3 deletions
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15
drivers/acpi/video.c
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@ -81,6 +81,13 @@ module_param(brightness_switch_enabled, bool, 0644);
static int allow_duplicates;
module_param(allow_duplicates, bool, 0644);
/*
* Some BIOSes claim they use minimum backlight at boot,
* and this may bring dimming screen after boot
*/
static int use_bios_initial_backlight = 1;
module_param(use_bios_initial_backlight, bool, 0644);
static int register_count = 0;
static int acpi_video_bus_add(struct acpi_device *device);
static int acpi_video_bus_remove(struct acpi_device *device, int type);
@ -766,9 +773,11 @@ acpi_video_init_brightness(struct acpi_video_device *device)
* when invoked for the first time, i.e. level_old is invalid.
* set the backlight to max_level in this case
*/
for (i = 2; i < br->count; i++)
if (level_old == br->levels[i])
level = level_old;
if (use_bios_initial_backlight) {
for (i = 2; i < br->count; i++)
if (level_old == br->levels[i])
level = level_old;
}
goto set_level;
}