Re: [PATCH v2 4/8] dt-bindings: iio: adc: add input-channel-rotation property

[Conor Dooley <conor@kernel.org>]

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On Thu, Jun 25, 2026 at 04:55:06PM -0500, David Lechner (TI) wrote:
> Add a generic input-channel-rotation property to adc.yaml. This is a
> feature seen frequently in ADCs that are designed to measure resistive
> loads, such as RTDs and strain gauges. Enabling this can reduce offset
> errors by swapping the positive and negative input channels on every
> other conversion. This can have side-effects in timing and filter
> response, so it is not always desirable to enable this feature in some
> applications. Therefore, it is best to make this a property that can be
> enabled or disabled in the device tree.
> 
> Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
> ---
> v2 changes:
> * New patch.
> ---
>  Documentation/devicetree/bindings/iio/adc/adc.yaml | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> index 9ec1f447b565..3d52c00922c9 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> @@ -81,6 +81,13 @@ properties:
>        ADCs usually allow choosing between internal reference sources or a pair
>        of external pins.
>  
> +  input-channel-rotation:
> +    type: boolean
> +    description:
> +      If set, the positive and negative input channels are allowed to be swapped
> +      on every other conversion to reduce offset errors. This is also referred
> +      to as "chop" in some datasheets.

"allowed to be swapped" means that this property says the feature can be
used, but userspace may have to be the thing that ultimately turns it
on?

> +
>    excitation-channels:
>      $ref: /schemas/types.yaml#/definitions/uint32-array
>      description:
> 
> -- 
> 2.43.0
> 

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