Re: [PATCH] iio: acpi: Add ACPI0008 Ambient Light Sensor
From: Gabriele Mazzotta
Date: Thu Apr 30 2015 - 07:27:52 EST
On Thursday 30 April 2015 11:44:36 Marek Vasut wrote:
> On Wednesday, April 29, 2015 at 05:36:32 PM, Gabriele Mazzotta wrote:
> > > > I'm sorry, I've just noticed that I haven't changed the value of
> > > > realbits in acpi_als_channels. This makes me wonder what would be the
> > > > proper value, given that this is a generic driver and all the
> > > > information I have are those in the ACPI specification (which states
> > > > what I reported here above).
> > > >
> > > > Should I just set realbits to 32?
> > >
> > > I believe the ALS reports only 16bit signel value, no ?
> > > My observation with a strong coherent light source is that
> > > the saturated sensor reported 0xffff .
> > Probably it's the same for me. I couldn't get to the point where
> > ALI reports 0xffff, just really close, I will have to try with some
> > stronger lights. However, looking at my ACPI table, I can see that
> > the value returned by _ALI is just the composition of two 8 bits
> > variables put side by side, so yes, I can say that even on my system
> > it's a 16bit value.
> What kind of hardware are you testing this on ?
Dell XPS13 9333.
> > The problem here is that I'm not sure we can assume this as true in
> > general since the ACPI specification doesn't say anything.
> Maybe someone more knowledgable can speak up.
I'm looking at some documentation from Microsoft  on how to use these
sensors in Windows and values as high as 100,000 lux are mentioned.
> Best regards,
> Marek Vasut
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