Re: [PATCH v3 08/13] dt-bindings: iio: adc: adi,ad4134: Document SPI connection mode

[Rob Herring <robh@kernel.org>]

On Tue, Sep 29, 2026 at 07:44:22PM -0300, Marcelo Schmitt wrote:
> Document how AD4134 chips are connected to the host SPI controller
> according to different wiring configurations.
> 
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
> ---
> Change log v2 -> v3:
> - Adjusted spi-rx-bus-width constraints.
> 
> Unfortunately, I missed SPI connection mode properties when introducing AD4134
> dt-doc and the device driver defaulted to a no-CS configuration. Due to that,
> conventional 4-wire mode can't be made default without leading to a regression.
> Still, updating the SPI mode default to 4-wire is a sensible thing to do later
> on if acceptable.
> 
>  .../bindings/iio/adc/adi,ad4134.yaml          | 51 ++++++++++++++++---
>  1 file changed, 44 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
> index ea6d7e026419..0b2a2cbfadae 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
> @@ -131,6 +131,26 @@ properties:
>      enum: [ free-running, gated ]
>      default: gated
>  
> +  adi,spi-mode:
> +    $ref: /schemas/types.yaml#/definitions/string
> +    enum: [ no-cs, 4-wire, one-channel-chain, two-channel-chain ]
> +    default: no-cs
> +    description: |
> +      This property indicates the SPI wiring configuration.
> +      * no-cs: The datasheet calls this "minimum I/O mode". In this mode, the CS
> +        line is not used (tied to GND).
> +      * 4-wire: Specifies a conventional SPI wiring configuration.
> +      * one-channel-chain: In this mode, the DOUT0 line of one chip is connected
> +        to DOUT2 of the next chip upstream in the chain. Only the data interface
> +        of the upmost device in the stream is in direct connection with the
> +        digital host.
> +      * two-channel-chain: In this mode, the DOUT0 and DOUT1 lines of one chip
> +        are respectively connected to DOUT2 and DOUT3 of the next chip upstream
> +        in the chain. Only the data interface of the upmost device in the stream
> +        is in direct connection with the digital host.
> +
> +  '#daisy-chained-devices': true
> +
>  required:
>    - compatible
>    - reg
> @@ -141,13 +161,30 @@ required:
>    - clocks
>    - clock-names
>  
> -oneOf:
> -  - required:
> -      - ldoin-supply
> -  - required:
> -      - avdd1v8-supply
> -      - dvdd1v8-supply
> -      - clkvdd-supply
> +allOf:
> +  - oneOf:
> +      - required:
> +          - ldoin-supply
> +      - required:
> +          - avdd1v8-supply
> +          - dvdd1v8-supply
> +          - clkvdd-supply
> +
> +  - oneOf:
> +      - required: [adi,spi-mode, '#daisy-chained-devices']
> +        properties:
> +          adi,spi-mode:
> +            const: one-channel-chain
> +          spi-rx-bus-width:
> +            const: 1
> +      - required: [adi,spi-mode, '#daisy-chained-devices']
> +        properties:
> +          adi,spi-mode:
> +            const: two-channel-chain
> +          spi-rx-bus-width:
> +            const: 1, 1

This is not valid. I think it evaluates to a string. You want:

items:
  - const: 1
  - const: 1

Rob