Re: [PATCH v5 1/3] dt-bindings: hwmon: Add Microchip emc2305 support

[Guenter Roeck]

On 3/18/25 08:33, Daniel Baluta wrote:
> On Tue, Mar 18, 2025 at 5:22 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > On 3/18/25 01:54, florin.leotescu@xxxxxxxxxxx wrote:
> > > From: Florin Leotescu <florin.leotescu@xxxxxxx>
> > >
> > > Introduce yaml schema for Microchip emc2305 pwm fan controller.
> > >
> > > Signed-off-by: Florin Leotescu <florin.leotescu@xxxxxxx>
> > > Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> > > ---
> > >    .../bindings/hwmon/microchip,emc2305.yaml     | 113 ++++++++++++++++++
> > >    1 file changed, 113 insertions(+)
> > >    create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > > new file mode 100644
> > > index 000000000000..e61ef97e63af
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > > @@ -0,0 +1,113 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +
> > > +$id: http://devicetree.org/schemas/hwmon/microchip,emc2305.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Microchip EMC2305 SMBus compliant PWM fan controller
> > > +
> > > +maintainers:
> > > +  - Michael Shych <michaelsh@xxxxxxxxxx>
> > > +
> > > +description:
> > > +  Microchip EMC2301/2/3/5 pwm controller which supports
> > > +  up to five programmable fan control circuits.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    oneOf:
> > > +      - enum:
> > > +          - microchip,emc2305
> > > +      - items:
> > > +          - enum:
> > > +              - microchip,emc2303
> > > +              - microchip,emc2302
> > > +              - microchip,emc2301
> > > +          - const: microchip,emc2305
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  '#address-cells':
> > > +    const: 1
> > > +
> > > +  '#size-cells':
> > > +    const: 0
> > > +
> > > +  '#pwm-cells':
> > > +    const: 3
> > > +    description: |
> > > +      Number of cells in a PWM specifier.
> > > +      - cell 0: The PWM frequency
> > > +      - cell 1: The PWM polarity: 0 or PWM_POLARITY_INVERTED
> > > +      - cell 2: The PWM output config:
> > > +           - 0 (Open-Drain)
> > > +           - 1 (Push-Pull)
> > > +
> > > +
> > > +patternProperties:
> > > +  '^fan@[0-4]$':
> > > +    $ref: fan-common.yaml#
> > > +    unevaluatedProperties: false
> > > +    properties:
> > > +      reg:
> > > +        description:
> > > +          The fan number used to determine the associated PWM channel.
> > > +
> > > +    required:
> > > +      - reg
> > > +      - pwms
> >
> > Is it necessary to make 'pwms' mandatory ? The current code works
> > just fine with defaults.
>
> The code adding OF support is added just in the next patch, so the
> current code isn't event
> probed when trying to use dts.
>
> Or am I missing something?

The patch introducing devicetree support to the driver doesn't evaluate
the pwm property. That makes it quite obvious that, from driver perspective,
it isn't needed. I don't immediately see why it would add value to _force_
users to provide pwm frequency, polarity, and the output configuration
if the defaults work just fine.

Guenter