On Tue, 2010-12-14 at 13:10 +0800, Len Brown wrote: > 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. yes. > should there be a way to invoke this workaround automatically? > no. because it's hard for software to detect if the screen is dark. maybe we need another dmi list for this issue. thanks, rui > 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
