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

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Date: Sat, 10 Feb 2024 16:46:41 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Conor Dooley <conor@...nel.org>
Cc: Naresh Solanki <naresh.solanki@...ements.com>, Peter Rosin
 <peda@...ntia.se>, 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, 6 Feb 2024 15:22:29 +0000
Conor Dooley <conor@...nel.org> wrote:

> 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.
I've made the change and applied this patch. Given it will only initially
be pushed out for 0-day to take a look at it, feel free to shout if you'd
prefer different wording from Conor's suggestion.

Thanks,

Jonathan

> 
> 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
> >