On Thu, 2010-04-01 at 09:34 +0800, Zhang Rui wrote:
> On Thu, 2010-04-01 at 09:19 +0800, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@xxxxxxx>
> >
> > On Acer Ferrari One, when _BQC is invoked for the first time, the
> > minimum brightness is returned, so the ACPI video drivers sets the
> > minimum brightness on boot. This is not desirable, so use the
> > following rule:
> > If _BQC initially returns an invalid value or the minimum
> > brightness, use either the brightness level supposed to be
> > used on AC power, or the brightness level supposed to be
> > used on battery, depending on whether or not the system is
> > on AC power. If these values are not exported by the BIOS,
> > use the maximum brightness level.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> > ---
> > drivers/acpi/video.c | 26 +++++++++++++++++++++++---
> > 1 file changed, 23 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
> > @@ -44,6 +44,7 @@
> > #include <acpi/acpi_bus.h>
> > #include <acpi/acpi_drivers.h>
> > #include <linux/suspend.h>
> > +#include <linux/power_supply.h>
> >
> > #define PREFIX "ACPI: "
> >
> > @@ -920,11 +928,20 @@ acpi_video_init_brightness(struct acpi_v
> > * Set the backlight to the initial state.
> > * On some buggy laptops, _BQC returns an uninitialized value
> > * when invoked for the first time, i.e. level_old is invalid.
> > - * set the backlight to max_level in this case
> > + * On some other systems _BQC returns the minimum brightness
> > + * when invoked for the first time, which also usually is
> > + * undesirable. In that cases use the "AC power" value if on AC
> > + * power or the "battery" value otherwise. If these vaules are
> > + * not exported, use max_level.
> > */
> > - for (i = 2; i < br->count; i++)
> > - if (level_old == br->levels[i])
> > + for (i = 3; i < br->count; i++)
> > + if (level_old == br->levels[i]) {
> > level = level_old;
> > + goto set_level;
> > + }
> > + if (!br->flags._BCL_no_ac_battery_levels)
> > + level = power_supply_is_system_supplied() ?
> > +
> > br->levels[0] : br->levels[1];
>
> this doesn't work currently.
> br->levels[0] and br->levels[1] doesn't equal the "AC power" value and
> "Battery" value, because the "AC power" and "Battery" value is not
> exported by many BIOS at all.
I mean, for these laptops, br->levels[0] and br->levels[1] equals the
first and second elements in _BCL package.
But we can not use them as the "AC power" and "Battery" value.
> But we can make it work if we fake the AC and Battery value for these
> laptops, which is not done yet. For example, set the AC power value the
> maximum brightness level, if it's not exported by BIOS.
>
> thanks,
> rui
>
>
>
> > goto set_level;
> > }
> >
> > --
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>
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