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Commit 99fd1895 authored by Zhang Rui's avatar Zhang Rui Committed by Len Brown
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ACPI video: introduce module parameter video.use_bios_initial_backlight 

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: default avatarZhang Rui <rui.zhang@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent cf7d7e5a

drivers/acpi/video.c

+12 −3
Original line number Diff line number Diff line
@@ -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

		 */

		if (use_bios_initial_backlight) {

			for (i = 2; i < br->count; i++)

				if (level_old == br->levels[i])

					level = level_old;

		}

		goto set_level;

	}