linux-kernel - Re: [RFC PATCH v1 0/2] hwmon: (iio_hwmon) optionally force iio channel type

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Message-Id: <CBER9H2H2I30.25AABLQDA7CD3@shaak>
Date:   Sun, 16 May 2021 10:55:40 -0400
From:   "Liam Beguin" <liambeguin@...il.com>
To:     "Guenter Roeck" <linux@...ck-us.net>, <jdelvare@...e.com>,
        <jic23@...nel.org>, <lars@...afoo.de>, <pmeerw@...erw.net>
Cc:     <linux-hwmon@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <robh+dt@...nel.org>
Subject: Re: [RFC PATCH v1 0/2] hwmon: (iio_hwmon) optionally force iio
 channel type

Hi Guenter,

On Sun May 16, 2021 at 4:56 AM EDT, Guenter Roeck wrote:
> On 5/15/21 9:43 PM, Liam Beguin wrote:
> > Add a devicetree binding to optionally force a different IIO channel
> > type.
> > 
> > This is useful in cases where ADC channels are connected to a circuit
> > that represent another unit such as a temperature or a current.
> > 
> > `channel-types` was chosen instead of `io-channel-types` as this is not
> > part of the iio consumer bindings.
> > 
> > In the current form, this patch does what it's intended to do:
> > change the unit displayed by `sensors`, but feels like the wrong way to
> > address the problem.
> > 
> > Would it be possible to force the type of different IIO channels for
> > this kind of use case with a devicetree binding from the IIO subsystem?
> > 
>
> That doesn't make sense to me. If an ADC is used to report temperatures,
> it would be a thermistor, and the ntc_thermistor driver should be used.
> Not sure what to do with currents, but overriding "voltage" with
> "current"
> seems wrong.

Thanks for pointing out the ntc_thermistor.
It makes sense that the ADC channel would become a thermistor.
I'll have a look and see if it fits my use case.

Liam

>
> Guenter
>
> > It would be convenient to do it within the IIO subsystem to have the
> > right unit there too.
> > 
> > Thanks for your time,
> > Liam
> > 
> > Liam Beguin (2):
> >    hwmon: (iio_hwmon) optionally force iio channel type
> >    dt-bindings: hwmon: add iio-hwmon bindings
> > 
> >   .../devicetree/bindings/hwmon/iio-hwmon.yaml  | 41 +++++++++++++++++++
> >   drivers/hwmon/iio_hwmon.c                     |  2 +
> >   2 files changed, 43 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/hwmon/iio-hwmon.yaml
> > 
> > 
> > base-commit: 9f4ad9e425a1d3b6a34617b8ea226d56a119a717
> >