linux-kernel - Re: [PATCH 3/4] dt-bindings: iio: dac: add mcp4822

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Date:   Wed, 05 Apr 2023 16:17:54 +0200
From:   Nicolas Frattaroli <frattaroli.nicolas@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] dt-bindings: iio: dac: add mcp4822

On Mittwoch, 5. April 2023 16:10:10 CEST Krzysztof Kozlowski wrote:
> On 05/04/2023 16:01, Nicolas Frattaroli wrote:
> > The MCP4801, MCP4802, MCP4811, MCP4812, MCP4821, and MCP4822 are
> > SPI digital-to-analog converters by Microchip, which have an
> > internal voltage reference, in contrast to the MCP49xx series
> > of DACs which use an external voltage reference.
> > 
> > Thus, these need a separate binding, as to not overcomplicate
> > the mcp4922 binding.
> 
> The difference is just one property which is very easy to handle - one
> allOf:if:then: with
>     vref-supply: false
> 
> Are there any other differences?
> 
> Best regards,
> Krzysztof
> 
> 

In place of the external vref input, the MCP48XX series chips also
have a "SHDN" input, which is an active-low pin to disable the whole
chip and put it in a low power state. Future users of the bindings
may want to model this as being tied to some GPIO, though I haven't
done it here since I don't care about this feature.

Kind regards,
Nicolas Frattaroli