linux-kernel - Re: [PATCH v4 5/6] dt-bindings: iio: adc: Add AD4000

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Date: Wed, 19 Jun 2024 14:04:14 -0300
From: Marcelo Schmitt <marcelo.schmitt1@...il.com>
To: David Lechner <dlechner@...libre.com>
Cc: Marcelo Schmitt <marcelo.schmitt@...log.com>, broonie@...nel.org,
	lars@...afoo.de, Michael.Hennerich@...log.com, jic23@...nel.org,
	robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
	conor+dt@...nel.org, nuno.sa@...log.com, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 5/6] dt-bindings: iio: adc: Add AD4000

On 06/19, David Lechner wrote:
> On 6/18/24 6:12 PM, Marcelo Schmitt wrote:
> > Add device tree documentation for AD4000 series of ADC devices.
> > 
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad4000-4004-4008.pdf
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad4001-4005.pdf
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad4002-4006-4010.pdf
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad4003-4007-4011.pdf
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad4020-4021-4022.pdf
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/adaq4001.pdf
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/adaq4003.pdf
> 
> Datasheets URLs are listed in the patch, so probably don't need them
> in the commit message too.

okay, removed them for v5.

> 
...
> 
> There are data sheets listed for adaq400x but no compatibles.

Ah, that's correct. I missed
      - const: adi,adaq4001
      - const: adi,adaq4003

thanks
> 
...
> > +
> > +  adi,gain-milli:
> > +    description: |
> > +      The hardware gain applied to the ADC input (in milli units).
> > +      The gain provided by the ADC input scaler is defined by the hardware
> > +      connections between chip pins OUT+, R1K-, R1K1-, R1K+, R1K1+, and OUT-.
> > +      If not present, default to 1000 (no actual gain applied).
> > +    $ref: /schemas/types.yaml#/definitions/uint16
> 
> Any particular reason why this needs to be uint16 instead of the more
> common uint32?

The values fit into 16 bits and Nuno asked to make it a 16-bit property.

> 
> > +    enum: [454, 909, 1000, 1900]
> > +    default: 1000
> > +
...
> > +  # The configuration register can only be accessed in '3-wire' mode
> > +  - if:
> > +      not:
> > +        properties:
> > +          adi,spi-mode:
> > +            contains:
> > +              enum:
> > +                - single
> 
> adi,spi-mode is not an array and we are only checking for one value,
> so this could be simplified to:
> 
>   properties:
>     adi,spi-mode:
>       const: single
> 
ok, changed to do the check that way.

...
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +        /* Example for a AD devices */
> 
> Comments are a bit redundant since it says "examples:" above and
> the type of the chip in the compatible string.
> 
I like the comments. I think it makes clear we have AD and ADAQ devices but ok,
removing them for v5.

> > +        adc@0 {
> > +            compatible = "adi,ad4020";
> > +            reg = <0>;
> > +            spi-max-frequency = <71000000>;
> > +            vdd-supply = <&supply_1_8V>;
> > +            vio-supply = <&supply_1_8V>;
> > +            ref-supply = <&supply_5V>;
> > +            cnv-gpios = <&gpio0 88 GPIO_ACTIVE_HIGH>;
> > +        };
> > +    };
> > +  - |
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +        /* Example for a ADAQ devices */
> > +        adc@0 {
> > +            compatible = "adi,adaq4003";
> > +            reg = <0>;
> > +            spi-max-frequency = <80000000>;
> > +            vdd-supply = <&supply_1_8V>;
> > +            vio-supply = <&supply_1_8V>;
> > +            ref-supply = <&supply_5V>;
> > +            adi,high-z-input;
> > +            adi,gain-milli = /bits/ 16 <454>;
> > +            adi,spi-mode = "single";
> > +        };
> > +    };