On Tue, 2009-02-03 at 21:56 +0800, Thomas Renninger wrote:
> On Monday 02 February 2009 04:33:41 yakui_zhao wrote:
> > Subject: ACPI: Skip the first two elements in the _BCL package
> > From: Zhao Yakui <yakui.zhao@xxxxxxxxx>
> > According to the Spec the first two elements in the _BCL package won't
> > be regarded as the available brightness level. The first is the brightness
> > when full power is connected to the box(It means that the AC adapter is
> > plugged). The second is the brightness level when the box is on battery.
> > If the first two elements are still used while finding the next
> > brightness level, it will fall back to the lowest level when keeping on
> > pressing hotkey. (On some boxes the brightness will be changed twice when
> > hotkey is pressed once. One is in the ACPI video driver. The other is
> > changed by sys I/F. In the ACPI video driver the first two elements will be
> > used while changing the brightness. But the first two elements is skipped
> > while using sys I/F. In such case there exists the inconsistency).
> > So he first two elements had better be skipped while showing the
> > available brightness or finding the next brightness level.
> I remember that Rui pointed me to a brightness level list, which included
> a value in AC/battery values which was not in the rest of the list.
> I expect simply ignoring battery/AC values is not right.
Understand what you said. On some boxes the AC/battery level is not
included by the rest brightness level.
>From the spec the rest are treated as the list of levels OSPM can cycle
through when user toggles(via keystroke) the brightness level of the
display.
If so, the first two elements should be excluded in the available
brightness levels for hotkey.
And the first two elements are only used for that the power is
switched between AC and battery.
Right?
> I posted a patch a while ago which did:
> - Go through the brightness values and extract from all (including
> AC and battery) unique values
> - Sort them
> - Create a with the data a new list.
> Not sure whether this would have worked, but something is still
> missing. Currently we do not use battery/AC values, but what if we want
> do that, e.g. exporting them to userspace?
In current driver the BIOS flag of the _DOD input argument is zero,
which means that the BIOS will automatically control the brightness of
level when the power is switched between AC and DC.
If we expect to change the brightness when switching power between
AC and DC, it is necessary to export them to user space.
Can we still use the brightness sys I/F to change the brightness
for AC/DC? The current sys I/F only exports the available brightness
level that can be changed via hotkey. Maybe we should use another I/F to
change the brightness for AC/DC.
> Then trying to set them will fail.
> We either need to consider AC/battery levels or we need to
> take the closest level if it's not included in the list. I
> expect the first is correct, otherwise it would be stupid from
> the vendors to provide an AC/battery level which cannot be set.
>
> I expect we still miss a little piece of Windows compatibility here ...
>
> Thomas
>
>
> > http://bugzilla.kernel.org/show_bug.cgi?id=12450
> >
> > Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
> > cc: Zhang Rui <rui.zhang@xxxxxxxxx>
> > ---
> > drivers/acpi/video.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > Index: linux-2.6/drivers/acpi/video.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/acpi/video.c 2009-01-23 14:47:25.000000000 +0800
> > +++ linux-2.6/drivers/acpi/video.c 2009-02-02 11:11:55.000000000 +0800
> > @@ -1020,7 +1020,7 @@
> > }
> >
> > seq_printf(seq, "levels: ");
> > - for (i = 0; i < dev->brightness->count; i++)
> > + for (i = 2; i < dev->brightness->count; i++)
> > seq_printf(seq, " %d", dev->brightness->levels[i]);
> > seq_printf(seq, "\ncurrent: %d\n", dev->brightness->curr);
> >
> > @@ -1059,7 +1059,7 @@
> > return -EFAULT;
> >
> > /* validate through the list of available levels */
> > - for (i = 0; i < dev->brightness->count; i++)
> > + for (i = 2; i < dev->brightness->count; i++)
> > if (level == dev->brightness->levels[i]) {
> > if (ACPI_SUCCESS
> > (acpi_video_device_lcd_set_level(dev, level)))
> > @@ -1712,7 +1712,7 @@
> > max = max_below = 0;
> > min = min_above = 255;
> > /* Find closest level to level_current */
> > - for (i = 0; i < device->brightness->count; i++) {
> > + for (i = 2; i < device->brightness->count; i++) {
> > l = device->brightness->levels[i];
> > if (abs(l - level_current) < abs(delta)) {
> > delta = l - level_current;
> > @@ -1722,7 +1722,7 @@
> > }
> > /* Ajust level_current to closest available level */
> > level_current += delta;
> > - for (i = 0; i < device->brightness->count; i++) {
> > + for (i = 2; i < device->brightness->count; i++) {
> > l = device->brightness->levels[i];
> > if (l < min)
> > min = l;
> >
> >
> > --
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