Re: [PATCH v8 v8 04/11] dt-bindings: iio: adc: hx711: add HX710B support

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 11 May 2026 23:13:29 +0530
Piyush Patle <piyushpatle228@gmail.com> wrote:

> Add the avia,hx710b compatible and document the HX710B-specific
> DVDD and VREF supplies.
Hi Piyush,

Sashiko moaned about this on v7 (it's not caught up with v8 yet)
and is correct in a sense as the hx711 seems to have a dvdd supply.
Your are documenting extra stuff that is hx710b specific but
the actual supply is there on both chips.

https://sashiko.dev/#/patchset/20260510194947.31997-1-piyushpatle228%40gmail.com

> 
> Add constraints that forbid HX711-only properties on HX710B nodes and
> require vref-supply for HX710B, then add a separate HX710B example.
> 
> Keep the existing HX711-only binding extensions in earlier patches so
> this change is limited to the new variant.

This bit isn't needed in the patch description and as per the dvdd-supply
isn't quite true.  I might just edit this whilst applying if nothing
comes up in rest of the series (I will be waiting for sashikio though
given how successful it is proving an find stuff I missed!)

> 
> Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> ---
>  .../bindings/iio/adc/avia-hx711.yaml          | 42 ++++++++++++++++++-
>  1 file changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
> index 9134bbe41379..b2b5c7bdf05e 100644
> --- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
> @@ -4,7 +4,7 @@
>  $id: http://devicetree.org/schemas/iio/adc/avia-hx711.yaml#
>  $schema: http://devicetree.org/meta-schemas/core.yaml#
>  
> -title: AVIA HX711 ADC chip for weight cells
> +title: AVIA HX711 and HX710B ADCs
>  
>  maintainers:
>    - Andreas Klinger <ak@it-klinger.de>
> @@ -14,9 +14,14 @@ description: |
>    differential input channels. Channel A supports gain 64 and 128;
>    channel B supports gain 32.
>  
> +  The HX710B is a 24-bit ADC with fixed gain of 128. One input measures
> +  the differential voltage between the two input pins; a second measures
> +  the DVDD-AVDD supply voltage difference for battery level detection.
> +
>  properties:
>    compatible:
>      enum:
> +      - avia,hx710b
>        - avia,hx711
>  
>    sck-gpios:
> @@ -44,6 +49,17 @@ properties:
>        RATE pin state is determined by the board wiring.
>      maxItems: 1
>  
> +  dvdd-supply:
Ah dvdd is here and whilst your text is talking about hx710b constraints
you don't stop it being supplied for the hx711 so you can ignore earlier comment.

> +    description:
> +      Digital supply voltage (DVDD). For the HX710B, DVDD must be
> +      greater than or equal to AVDD. When DVDD is a battery rail and
> +      AVDD is a regulated supply, one channel monitors the DVDD-AVDD
> +      difference for battery level detection.
> +
> +  vref-supply:
> +    description:
> +      Reference voltage input (VREF).
> +
>    clock-frequency:
>      description:
>        Controls the SCK bit-bang timing. The value is used to derive the
> @@ -53,6 +69,21 @@ properties:
>      maximum: 2500000
>      default: 400000
>  
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          const: avia,hx710b
> +    then:
> +      properties:
> +        vsup-supply: false
> +        rate-gpios: false
> +      required:
> +        - vref-supply
> +    else:
> +      properties:
> +        vref-supply: false
> +
>  required:
>    - compatible
>    - sck-gpios
> @@ -72,3 +103,12 @@ examples:
>          avdd-supply = <&avdd>;
>          clock-frequency = <100000>;
>      };
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    weight {
> +        compatible = "avia,hx710b";
> +        sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
> +        dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
> +        avdd-supply = <&avdd>;
> +        vref-supply = <&vref>;
> +    };