Re: [PATCH] Documentation: Add entry for dell-laptop sysfs interface

From: Darren Hart
Date: Thu Jan 01 2015 - 23:25:53 EST


On Wed, Dec 31, 2014 at 12:20:59PM +0100, Gabriele Mazzotta wrote:
> On Tuesday 30 December 2014 21:31:49 Brian Norris wrote:
> > Hi,
> >
> > On Wed, Dec 03, 2014 at 06:41:33PM +0100, Gabriele Mazzotta wrote:
> > > Add the documentation for the new sysfs interface of dell-laptop
> > > that allows to configure the keyboard illumination on Dell systems.
> > >
> > > Signed-off-by: Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>
> > > Signed-off-by: Pali Rohár <pali.rohar@xxxxxxxxx>
> > > ---
> > > .../ABI/testing/sysfs-platform-dell-laptop | 60 ++++++++++++++++++++++
> > > 1 file changed, 60 insertions(+)
> > > create mode 100644 Documentation/ABI/testing/sysfs-platform-dell-laptop
> > >
> > > diff --git a/Documentation/ABI/testing/sysfs-platform-dell-laptop b/Documentation/ABI/testing/sysfs-platform-dell-laptop
> > > new file mode 100644
> > > index 0000000..7969443
> > > --- /dev/null
> > > +++ b/Documentation/ABI/testing/sysfs-platform-dell-laptop
> > > @@ -0,0 +1,60 @@
> > > +What: /sys/class/leds/dell::kbd_backlight/als_setting
> > > +Date: December 2014
> > > +KernelVersion: 3.19
> > > +Contact: Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>,
> > > + Pali Rohár <pali.rohar@xxxxxxxxx>
> > > +Description:
> > > + This file allows to control the automatic keyboard
> > > + illumination mode on some systems that have an ambient
> > > + light sensor. Write 1 to this file to enable the auto
> > > + mode, 0 to disable it.
> > [...]
> >
> > This entry appears wrong, or at least incomplete. My system boots with a
> > default value of 18, and the 'set' implementation accepts any value from
> > 0 to 255.
> >
> > According to the comments in dell-laptop.c, the value actually means
> > something different than on/off:
> >
> > cbArg3, byte0 Desired setting of ALS value that turns the light on or off.
> >
> > Admittedly, I'm not clear on what the intended interface is, as I've
> > never had the ALS / keyboard backlight controls all working properly on
> > my laptop in the first place, but I thought this would be the right
> > place to ask about getting the documentation and driver in sync.
>
> Hi,
>
> You are perfectly right, the documentation is wrong and I'm sorry for
> that. als_setting should allow you to define when the keyboard
> backlight has to be turned on or off depending on the value reported
> by the ambient light sensor.
>
> Please note that not everything that is in libsmbios [1] is implemented
> in the kernel driver. Take a look at it, recently there have been few
> changes related to the ALS settings. Probably they are not needed given
> that you are able to set the threshold with the current kernel driver,
> but you might find something interesting.
>
> I'll submit a patch to correct the documentation, thanks for reporting.

Thanks Gabriele, let's make sure to get this into this rc cycle, sooner the
better.

Thanks,

--
Darren Hart
Intel Open Source Technology Center
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