Re: [PATCH 14/54] dt-bindings: hwmon: Add IIO HWMON binding

[Maxime Ripard <maxime@cerno.tech>]

Hi Jonathan,

On Thu, Jul 22, 2021 at 10:20:27AM +0100, Jonathan Cameron wrote:
> On Wed, 21 Jul 2021 16:03:44 +0200
> Maxime Ripard <maxime@cerno.tech> wrote:
> 
> > Even though we had the iio-hwmon driver for some time and a number of
> > boards using it already, we never had a binding for it. Let's add it
> > based on what the driver expects and the boards are providing.
> > 
> > Cc: Guenter Roeck <linux@roeck-us.net>
> > Cc: Jean Delvare <jdelvare@suse.com>
> > Cc: Jonathan Cameron <jic23@kernel.org>
> > Cc: linux-hwmon@vger.kernel.org
> > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > ---
> >  .../devicetree/bindings/hwmon/iio-hwmon.yaml  | 37 +++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/hwmon/iio-hwmon.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/hwmon/iio-hwmon.yaml b/Documentation/devicetree/bindings/hwmon/iio-hwmon.yaml
> > new file mode 100644
> > index 000000000000..49dd40f663a6
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/iio-hwmon.yaml
> > @@ -0,0 +1,37 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: "http://devicetree.org/schemas/hwmon/iio-hwmon.yaml#"
> > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> > +
> > +title: ADC-attached Hardware Sensor Device Tree Bindings
> > +
> > +maintainers:
> > +  - Jonathan Cameron <jic23@kernel.org>
> 
> I'd like to share the blame for this one.  Binding was originally added
> by Guenter.
> 
> https://lore.kernel.org/linux-iio/1359668588-13678-4-git-send-email-linux@roeck-us.net/
> https://lore.kernel.org/linux-iio/1359668588-13678-11-git-send-email-linux@roeck-us.net/
> :)
> 
> As bindings go this one has always been controversial because
> it's mapping between linux subsystems rather than really describing
> hardware.  We've had various discussions over the years on how to do
> this differently, but perhaps just documenting the current state is the
> way to go.  That doesn't stop us moving to something better in the
> future.

There's DT using it already, so I guess it's a bit too late to have that
discussion indeed :)

> > +
> > +description: >
> > +  Bindings for hardware monitoring devices connected to ADC controllers
> > +  supporting the Industrial I/O bindings.
> > +
> > +properties:
> > +  compatible:
> > +    const: iio-hwmon
> > +
> > +  io-channels:
> > +    minItems: 1
> > +    maxItems: 1024
> 
> Why 1024?

Ought to be enough for anyone :)

We have to set a maximum and I couldn't find any actual maximum
documented, if you prefer another value let me know

Maxime