On Mon, 6 Dec 2010, Zhang Rui wrote: > > Introduce module parameter video.use_bios_initial_backlight. there must be a more concise way to say that... > 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. this looks like a BIOS workaround. should there be a way to invoke this workaround automatically? thanks, -Len > > 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
