linux-kernel - Re: [PATCH v3 2/2] dt-bindings: iio: adc: add Texas Instruments ADS7924

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Message-ID: <20230115164326.7f03f6d9@jic23-huawei>
Date:   Sun, 15 Jan 2023 16:43:26 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Hugo Villeneuve <hugo@...ovil.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        hvilleneuve@...onoff.com, lars@...afoo.de, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] dt-bindings: iio: adc: add Texas Instruments
 ADS7924

On Sun, 15 Jan 2023 11:22:05 -0500
Hugo Villeneuve <hugo@...ovil.com> wrote:

> On Sun, 15 Jan 2023 15:57:21 +0100
> Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:
> 
> > On 13/01/2023 20:49, Hugo Villeneuve wrote:  
> > > From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > > 
> > > Add device tree bindings document for the Texas Instruments ADS7924
> > > ADC.
> > > 
> > > Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > > ---
> > >  .../bindings/iio/adc/ti,ads7924.yaml          | 112 ++++++++++++++++++
> > >  1 file changed, 112 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,ads7924.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads7924.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads7924.yaml
> > > new file mode 100644
> > > index 000000000000..24bbf95383b4
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads7924.yaml
> > > @@ -0,0 +1,112 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/iio/adc/ti,ads7924.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: TI ADS7924 4 channels 12 bits I2C analog to digital converter
> > > +
> > > +maintainers:
> > > +  - Hugo Villeneuve <hvilleneuve@...onoff.com>
> > > +
> > > +description: |
> > > +  Texas Instruments ADS7924 4 channels 12 bits I2C analog to digital converter
> > > +
> > > +  Specifications:
> > > +    https://www.ti.com/lit/gpn/ads7924
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: ti,ads7924
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  vref-supply:
> > > +    description:
> > > +      The regulator supply for the ADC reference voltage (AVDD)
> > > +
> > > +  reset-gpios:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  "#address-cells":
> > > +    const: 1
> > > +
> > > +  "#size-cells":
> > > +    const: 0
> > > +
> > > +  "#io-channel-cells":
> > > +    const: 1
> > > +
> > > +patternProperties:
> > > +  "^channel@[0-3]+$":
> > > +    $ref: adc.yaml
> > > +
> > > +    description: |
> > > +      Represents the external channels which are connected to the ADC.
> > > +
> > > +    properties:
> > > +      reg:
> > > +        description: |
> > > +          The channel number. It can have up to 4 channels numbered from 0 to 3.
> > > +        items:
> > > +          - minimum: 0
> > > +            maximum: 3
> > > +
> > > +      label:
> > > +        description: |
> > > +          Unique name to identify the channel.  
> > 
> > Drop description, it's coming from adc.yaml. Just "label: true"  
> 
> Done.
> 
> > > +
> > > +    required:
> > > +      - reg
> > > +
> > > +    additionalProperties: false  
> > 
> > You are not allowing anything else from adc.yaml. Is it on purpose?  
> 
> I am really not an expert with this Yaml stuff, and reading the documentation makes me probably more confused than before reading it :)
> 
> But one thing that is for sure is that these other properties in adc.yaml are not used in my driver:
> 
>   bipolar
>   diff-channels
>   settling-time-us
>   oversampling-ratio
> 
> So is it Ok then to use "additionalProperties: false"? I think so, but what is your recommandation?

Makes sense to me.  Whilst there are lots of things a channel can support, most
of them are hardware related and not universal.

Jonathan

> 
> Thank you,
> Hugo.
> 
> 
> > > +
> > > +additionalProperties: false
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - vref-supply
> > > +  - "#address-cells"
> > > +  - "#size-cells"
> > > +  
> > 
> > Best regards,
> > Krzysztof
> > 
> >   
> 
>