linux-kernel - Re: [PATCH v5 1/3] dt-bindings:iio:adc: add generic settling-time-us and oversampling-ratio channel properties

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Date:   Mon, 29 Mar 2021 11:25:32 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        David Jander <david@...tonic.nl>,
        Robin van der Gracht <robin@...tonic.nl>,
        linux-iio@...r.kernel.org, Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [PATCH v5 1/3] dt-bindings:iio:adc: add generic
 settling-time-us and oversampling-ratio channel properties

On Mon, 29 Mar 2021 09:31:29 +0200
Oleksij Rempel <o.rempel@...gutronix.de> wrote:

> Settling time and over sampling is a typical challenge for different IIO ADC
> devices. So, introduce channel specific settling-time-us and oversampling-ratio
> properties to cover this use case.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>  Documentation/devicetree/bindings/iio/adc/adc.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> index 912a7635edc4..d5bc86d2a2af 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> @@ -39,4 +39,12 @@ properties:
>        The first value specifies the positive input pin, the second
>        specifies the negative input pin.
>  
> +  settling-time-us:
> +    description:
> +      Time between enabling the channel and firs stable readings.

first

> +
> +  oversampling-ratio:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: Number of data samples which are averaged for each read.

I think I've asked about this in previous reviews, but I want a clear statement
of why you think this property is a feature of the 'board' (and hence should be
in device tree) rather than setting sensible defaults and leaving any control
to userspace?

Jonathan

> +
>  additionalProperties: true