Re: [PATCH v1 9/9] dt-bindings: iio: afe: add binding for temperature-sense-amplifier

Jonathan Cameron
2021-06-01T16:06:17Z

On Mon, 31 May 2021 10:03:23 -0400
"Liam Beguin" <liambeguin@gmail.com> wrote:

> Hi Peter,
>
> On Mon May 31, 2021 at 3:32 AM EDT, Peter Rosin wrote:
> > Hi!
> >
> > On 2021-05-30 02:59, Liam Beguin wrote:
> > > From: Liam Beguin <lvb@xiphos.com>
> > >
> > > An ADC is often used to measure other quantities indirectly. This
> > > binding describe one cases, the measurement of a temperature through a
> > > voltage sense amplifier such as the LTC2997.
> > >
> > > Signed-off-by: Liam Beguin <lvb@xiphos.com>
> >
> > What's the significant difference between this and the RTD binding? Does
> > not both simply scale/offset a voltage to a temperature?

I'm lost: what RTD binding?

> >
>
> The way I looked at it was one binding per sensor type (resistance
> driven, current driven, and voltage driven).
>
> Thinking about it more, these three bindings could be factorized into
> one if the user is required to enter parameters "by hand".

Don't. They are effectively different types of devices and we just end
up with a more complex binding if we try to cover them all.

There is an argument to go the other way and actually have bindings for
individual temperature sensors like the LTC2997. Then the parameters
become a driver problem rather than one for the binding.

Jonathan

>
> These could become something like:
> - sense-gain-mult
> - sense-gain-div
> - sense-offset
>
> I like the idea of having the "datasheet parameters" in the devicetree,
> but this would be a lot more versatile.
>
> What do you think?
>
> Cheers,
> Liam
>
> > Cheers,
> > Peter
>