On Sunday, August 09, 2015 11:26:04 PM Pali Rohár wrote:
> On Sunday 09 August 2015 23:20:26 Fabio D'Urso wrote:
> > On Tuesday, July 28, 2015 02:05:03 PM Pali Rohár wrote:
> > > On Tuesday 28 July 2015 13:56:32 Bjørn Mork wrote:
> > > > Pali Rohár <pali.rohar@xxxxxxxxx> writes:
> > > > > On Tuesday 28 July 2015 13:17:58 Bjørn Mork wrote:
> > > > >> Pali Rohár <pali.rohar@xxxxxxxxx> writes:
> > > > >> > I would like to write kernel patch for thinkpad_acpi.c to
> > > > >> > support keyboard backlight (like other modules in
> > > > >> > drivers/platform/x86/ tree),
> > > > >> > but last missing information is how to detect current level
> > > > >> > of brightness and check if backlight is supported...
> > > > >>
> > > > >> Based on the code you posted, I would assume that MLCG returns
> > > > >> the current brightness level. Did you test that?
> > > > >
> > > > > Of course and it returns:
> > > > >
> > > > > 0x50200 - off
> > > > > 0x50201 - level 1
> > > > > 0x50202 - level 2
> > > > >
> > > > > But I do not understand why it returns 0x5020{0,1,2} and not
> > > > > only 0,1,2.
> > > >
> > > > Looks like it might have several bitfields with different
> > > > meanings. You'll probably have to guess what they are.
> > >
> > > Yes... Last number looks like current level. But what others? Maybe
> > > it represent if backlight feature is supported? Do not know.
> > >
> > > But it would be good, if more people with Thinkpad machines with
> > > and also without keyboard backligth send output from "MLCG" ACPI
> > > call.
> >
> > I can confirm that everything is as you described also on my W541
> > (with backlight), except for the line
> >
> > OperationRegion (MNVS, SystemMemory, 0xCCD7D018, 0x1000)
> >
> > which is actually
> >
> > OperationRegion (MNVS, SystemMemory, 0x7CE7D018, 0x1000)
> >
> > The rest of the DSDT code is like yours, MLCG always returns
> > 0x5020{0,1,2} and MLCS {0,1,2} works as expected and returns 0x0.
> >
> > I have also toggled the Fn lock and Ctrl/Fn swapping, but the
> > mysterious 0x5020n did not change. I have the latest BIOS version
> > (2.21).
> >
> > Fabio D'Urso
>
> Thanks for confirmation. Now I need dumps also from machines without
> backlight keyboard, but with MLCG method.
Hi, I have news from the I-have-the-backlight side:
If you set the 0x20000 bit in /proc/acpi/ibm/hotkey, you'll get a 0x1012
hotkey notification when the backlight brightness changes.
xev shows such events as XF86KbdLightOnOff key.
This notification happens when you press Fn+SPACE, but also when you call
MLCS. Even with this bit set, the hardware still takes care of cycling the
brightness levels on its own.
By the way, in my previous message I forgot to point out that MLCG actually
takes a numeric argument, but then ignores it. This can be seen from the DSDT
dump you posted, so I'm sure you already noticed. But maybe this information
can be useful to those who want to report data from their ThinkPads.
Fabio D'Urso
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