Re: [PATCH v2 1/6] dt-bindings: hwmon: add binding for adi,adt7470

[Guenter Roeck]

On 7/19/26 23:47, Krzysztof Kozlowski wrote:
> On Fri, Jul 17, 2026 at 05:59:14PM -0300, Luiz Angelo Daros de Luca wrote:
> > The Analog Devices ADT7470 is a temperature monitor and PWM fan
> > controller. It supports up to 10 external temperature sensors and
> > up to 4 PWM fan outputs.
>
> A nit, subject: drop second/last, redundant "binding for". The
> "dt-bindings" prefix is already stating that these are bindings.
> See also:
> https://elixir.bootlin.com/linux/v7.1-rc7/source/Documentation/devicetree/bindings/submitting-patches.rst#L23
>
> > Add the YAML device tree binding documentation for it. This includes
>
> s/YAML//
> There is no YAML in Devicetree.
>
> > support for the thermal framework by defining the "#thermal-sensor-cells"
> > property, and support for the PWM subsystem by defining the "#pwm-cells"
> > property.
> >
> > Signed-off-by: Luiz Angelo Daros de Luca <luizluca@xxxxxxxxx>
> > ---
> >   .../devicetree/bindings/hwmon/adi,adt7470.yaml     | 62 ++++++++++++++++++++++
> >   1 file changed, 62 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/adi,adt7470.yaml b/Documentation/devicetree/bindings/hwmon/adi,adt7470.yaml
> > new file mode 100644
> > index 000000000000..14bb6359c91f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/adi,adt7470.yaml
> > @@ -0,0 +1,62 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/hwmon/adi,adt7470.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices ADT7470 hwmon sensor
> > +
> > +maintainers:
> > +  - Luiz Angelo Daros de Luca <luizluca@xxxxxxxxx>
> > +
> > +description: |
>
> Do not need '|' unless you need to preserve formatting.
>
> > +  The ADT7470 is a temperature monitor and multiple PWM outputs.
> > +  It supports monitoring up to 10 external temperature sensors and controlling
> > +  up to four fans.
>
> "controling fans" is confusing and suggests this is a fan controller, so
> you would need to reference proper schema for that. It is just PWM
> output, no? PWM output could also go to LEDs or motors (well, fan is a
> motor).
From the datasheet: "The ADT74701 controller is a multichannel
temperature sensor and PWM fan controller and fan speed monitor".

It is a fan controller which happens to use pwm signals to control
fan speeds. It is not a PWM controller, and its pwm outputs are not
intended to be used for anything but controlling fan speeds.

Technically it is _possible_ to use the pwm outputs to control
something else. But that does not mean that chip is a pwm controller.
It is still a fan controller. I don't mind modeling outputs as
non-fan-control pwm channels if that is what they are used for,
but that must be clearly distinguished in both the driver code
and the bindings.

Guenter