linux-kernel - Re: [PATCH v4] dt-bindings: iio: afe: voltage-divider: Add io-channel-cells

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Date: Tue, 6 Feb 2024 15:22:29 +0000
From: Conor Dooley <conor@...nel.org>
To: Naresh Solanki <naresh.solanki@...ements.com>
Cc: Peter Rosin <peda@...ntia.se>, Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, mazziesaccount@...il.com,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] dt-bindings: iio: afe: voltage-divider: Add
 io-channel-cells

On Tue, Feb 06, 2024 at 04:25:01PM +0530, Naresh Solanki wrote:
> Enable the voltage divider to both receive and provide measurement
> services by adding #io-channel-cells.
> 
> This is especially valuable in scenarios where an ADC has an analog
> frontend, like a voltage divider, and obtaining its raw value isn't
> interesting. It is desired to get the real voltage before the voltage
> divider.
> 
> Signed-off-by: Naresh Solanki <naresh.solanki@...ements.com>

Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>

Thanks for adding the example. I have one comment about the wording, cos
the last sentence doesn't really make sense without something referring
back to the scenario you describe.

> ---
>  .../devicetree/bindings/iio/afe/voltage-divider.yaml  | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml b/Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
> index dddf97b50549..fd3c511e1beb 100644
> --- a/Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
> +++ b/Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
> @@ -39,6 +39,17 @@ properties:
>      description: |
>        Channel node of a voltage io-channel.
>  
> +  '#io-channel-cells':
> +    description:
> +      In addition to consuming the measurement services of a voltage
> +      output channel, the voltage divider can act as a provider of
> +      measurement services to other devices. This is particularly
> +      useful in scenarios wherein an ADC has an analog frontend,
> +      such as a voltage divider, and then consuming its raw value
> +      isn't interesting.

> It is desired to get the real voltage
> +      before the voltage divider.

"In this case, the voltage before the divider is desired".

Perhaps Jonathan can make that change, provided you are okay with it.

Cheers,
Conor.

> +    const: 1
> +
>    output-ohms:
>      description:
>        Resistance Rout over which the output voltage is measured. See full-ohms.
> 
> base-commit: 99bd3cb0d12e85d5114425353552121ec8f93adc
> -- 
> 2.42.0
> 

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