From: Marek Vasut <marex@denx.de>
To: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>, linux-iio@vger.kernel.org
Subject: Re: Correctness of acpi-als channel mask
Date: Mon, 21 Dec 2015 15:45:00 +0100 [thread overview]
Message-ID: <201512211545.00537.marex@denx.de> (raw)
In-Reply-To: <CABFtUbTggGGs7s0QtA=FeZx_ejwFHTBuxyhD8H_gmo9=R-HjwA@mail.gmail.com>
On Monday, December 21, 2015 at 11:08:55 AM, Gabriele Mazzotta wrote:
> 2015-12-21 0:33 GMT+01:00 Marek Vasut <marex@denx.de>:
> > On Saturday, December 19, 2015 at 05:09:33 PM, Jonathan Cameron wrote:
> >> On 17/12/15 20:32, Gabriele Mazzotta wrote:
> >> > Hi,
> >> >
> >> > I have a question regarding the acpi-als driver.
> >> >
> >> > Currently acpi-als uses IIO_CHAN_INFO_RAW to report the data coming
> >> > from the sensor. However, as per the ACPI specification [1] (section
> >> > 9.2.2), these values represent the ambient light illuminance expressed
> >> > in lux. Wouldn't IIO_CHAN_INFO_PROCESSED be more appropriate in this
> >> > case as the data are in theory pre-processed by the firmware of the
> >> > platform?
> >>
> >> Looks like it to me as well. Cc'd Marek and Martin.
> >
> > Gotta say, I haven't looked at ACPI for a while now. My impression is
> > that these data are RAW and the system software can adjust them based on
> > the values in _ALR table. The result of that would be _PROCESSED I
> > think. But I might be entirely wrong.
>
> I'm not sure of this. _ALR returns an ambient light illuminance to
> display luminance mapping that suggests how to adjust the screen
> backlight. There are then _ALC and _ALT which report the ambient light
> color chromaticity and the ambient light color temperature respectively.
ALC and ALT are optional I believe (at least I recall my crappy old hardware
on which I first implemented this didn't have them at all). Thanks for
clarifying what the ALR means, I never really understood how that was supposed
to work in the first place .
> So I don't think there are adjustments we can perform.
If you think _PROCESSED is more appropriate, I will not oppose it. At this
point, you are the bigger expert on ALS :)
> >> > [1] http://www.acpi.info/DOWNLOADS/ACPIspec50.pdf
> >> >
> >> > Regards,
> >> > Gabriele
> >> > --
> >> > To unsubscribe from this list: send the line "unsubscribe linux-iio"
> >> > in the body of a message to majordomo@vger.kernel.org
> >> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
> > Best regards,
> > Marek Vasut
Best regards,
Marek Vasut
prev parent reply other threads:[~2015-12-21 14:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-17 20:32 Correctness of acpi-als channel mask Gabriele Mazzotta
2015-12-19 16:09 ` Jonathan Cameron
2015-12-20 23:33 ` Marek Vasut
[not found] ` <CABFtUbTggGGs7s0QtA=FeZx_ejwFHTBuxyhD8H_gmo9=R-HjwA@mail.gmail.com>
2015-12-21 14:45 ` Marek Vasut [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201512211545.00537.marex@denx.de \
--to=marex@denx.de \
--cc=gabriele.mzt@gmail.com \
--cc=jic23@kernel.org \
--cc=linux-iio@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.