On Friday 02 April 2010, Zhang Rui wrote:
> On Fri, 2010-04-02 at 03:45 +0800, Rafael J. Wysocki wrote:
> > On Thursday 01 April 2010, Zhang Rui wrote:
> > > 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.
> >
> > But if the BIOS doesn't export these values,
> > br->flags._BCL_no_ac_battery_levels will be true, won't it?
> >
> no.
> for example, I have seen a _BCL package like this: {100, 0, 10, 20, ...,
> 90, 100}.
> Only one value, not sure the "AC power" or "Battery" value, is returned,
> the br->flags._BCL_no_ac_battery_levels is also set in this case.
Yes, it is, and that's fine.
The code added by the patch won't be executed in that case.
> > ---
> > From: Rafael J. Wysocki <rjw@xxxxxxx>
> > Subject: ACPI / Video: Fix initial brightness problem on Acer Ferrari One (v. 2)
> >
> > 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:
> > Set brightness to either the 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
> > brightness level initially returned by _BQC. If that value
> > is invalid, use the maximum brightness level.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> > ---
> > drivers/acpi/video.c | 16 +++++++++++++++-
> > 1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > 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: "
> >
> > @@ -915,6 +916,18 @@ acpi_video_init_brightness(struct acpi_v
> >
> > br->flags._BQC_use_index = (level == max_level ? 0 : 1);
> >
> I think the patch will work if we add some code here:
>
> if (!br->flags._BCL_no_ac_battery_levels) {
> /* the "AC power" and "Battery" brightness value is not reliable */
> br->levels[0] = ...; /* the maximum value? */
> br->levels[1] = ...; /* br->levels[maximum -1 ]? */
> }
Well, the code that checks the "AC power" and "battery" levels does this:
for (i = 2; i < count; i++) {
if (br->levels[i] == br->levels[0])
level_ac_battery++;
if (br->levels[i] == br->levels[1])
level_ac_battery++;
}
if (level_ac_battery < 2) {
level_ac_battery = 2 - level_ac_battery;
br->flags._BCL_no_ac_battery_levels = 1;
so in your example case the code below won't use the "AC power" and "battery"
values, which I believe is correct. [We'll try to use the initial brightness
and fall back to max_level in that case, as described in the changelog.]
> > + /*
> > + * Set brightness to the "AC power" value if on AC power or to the
> > + * "battery" value otherwise. If these vaules are not exported, try
> > + * to use the value returned by the initial _BQC and fall back to
> > + * max_level.
> > + */
> > + if (!br->flags._BCL_no_ac_battery_levels) {
> > + level = power_supply_is_system_supplied() ?
> > + br->levels[0] : br->levels[1];
> > + goto set_level;
> > + }
> > +
> > if (!br->flags._BQC_use_index) {
> > /*
> > * Set the backlight to the initial state.
> > @@ -930,7 +943,8 @@ acpi_video_init_brightness(struct acpi_v
> >
> > if (br->flags._BCL_reversed)
> > level_old = (br->count - 1) - level_old;
> > - level = br->levels[level_old];
> > + level = level_old >= 0 && level_old < br->count ?
> > + br->levels[level_old] : max_level;
> >
> > set_level:
> > result = acpi_video_device_lcd_set_level(device, level);
Thanks,
Rafael
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