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@xxxxxxxxx> --- drivers/acpi/video.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) Index: linux-2.6/drivers/acpi/video.c =================================================================== --- linux-2.6.orig/drivers/acpi/video.c +++ linux-2.6/drivers/acpi/video.c @@ -80,6 +80,13 @@ module_param(brightness_switch_enabled, 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); @@ -705,9 +712,11 @@ acpi_video_init_brightness(struct acpi_v * 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
