linux-kernel - Re: [PATCH v2 1/2] dt-bindings: iio: dac: add MCP4821

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Message-ID: <CAMknhBHoK-ZB1MpJmM3jbbBpyCbRYcRWPG02fxJ5OY6PLB7ZEg@mail.gmail.com>
Date: Sun, 17 Dec 2023 19:29:40 -0600
From: David Lechner <dlechner@...libre.com>
To: Anshul Dalal <anshulusr@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org, 
	Jonathan Cameron <jic23@...nel.org>, devicetree@...r.kernel.org, 
	Conor Dooley <conor+dt@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	linux-kernel-mentees@...ts.linuxfoundation.org, 
	Shuah Khan <skhan@...uxfoundation.org>, Conor Dooley <conor.dooley@...rochip.com>
Subject: Re: [PATCH v2 1/2] dt-bindings: iio: dac: add MCP4821

On Sun, Dec 17, 2023 at 7:25 PM David Lechner <dlechner@...libre.com> wrote:
>
> On Sun, Dec 17, 2023 at 12:11 PM Anshul Dalal <anshulusr@...il.com> wrote:
> >
> > Adds support for MCP48xx series of DACs.
> >
> > Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf #MCP48x1
> > Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf #MCP48x2
> > Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
> > Signed-off-by: Anshul Dalal <anshulusr@...il.com>
> >
> > ---
> >
> > Changes for v2:
> > - Changed order in device table to numerical
> > - Made vdd_supply required
> > - Added 'Reviewed-by: Conor Dooley'
> >
> > Previous versions:
> > v1: https://lore.kernel.org/lkml/20231117073040.685860-1-anshulusr@gmail.com/
> > ---
> >  .../bindings/iio/dac/microchip,mcp4821.yaml   | 64 +++++++++++++++++++
> >  1 file changed, 64 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/dac/microchip,mcp4821.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/iio/dac/microchip,mcp4821.yaml b/Documentation/devicetree/bindings/iio/dac/microchip,mcp4821.yaml
> > new file mode 100644
> > index 000000000000..97da9f9ef450
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/dac/microchip,mcp4821.yaml
> > @@ -0,0 +1,64 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/iio/dac/microchip,mcp4821.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Microchip MCP4821 and similar DACs
> > +
> > +description: |
> > +  Supports MCP48x1 (single channel) and MCP48x2 (dual channel) series of DACs.
> > +  Device supports simplex communication over SPI in Mode 0,1 and Mode 1,1.
>
> It seems like SPI modes usually only have one number in them, i.e.
> mode 1 and mode 3 in this case, I'm guessing.

Oh, and doesn't this mean that we need to include spi-cpha and
spi-cpol properties since they aren't implicit in the bindings anymore
since [1]?

[1]: https://lore.kernel.org/all/20220722191539.90641-2-krzysztof.kozlowski@linaro.org/

>
> > +
> > +  +---------+--------------+-------------+
> > +  | Device  |  Resolution  |   Channels  |
> > +  |---------|--------------|-------------|
> > +  | MCP4801 |     8-bit    |      1      |
> > +  | MCP4802 |     8-bit    |      2      |
> > +  | MCP4811 |    10-bit    |      1      |
> > +  | MCP4812 |    10-bit    |      2      |
> > +  | MCP4821 |    12-bit    |      1      |
> > +  | MCP4822 |    12-bit    |      2      |
> > +  +---------+--------------+-------------+
> > +
> > +  Datasheet:
> > +    MCP48x1: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf
> > +    MCP48x2: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf
> > +
> > +maintainers:
> > +  - Anshul Dalal <anshulusr@...il.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - microchip,mcp4801
> > +      - microchip,mcp4802
> > +      - microchip,mcp4811
> > +      - microchip,mcp4812
> > +      - microchip,mcp4821
> > +      - microchip,mcp4822
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  vdd-supply: true
>
> What about the SHDN and LDAC pins? It seems like all should have an
> ldac-gpios property and MCP48x1 should have a shdn-gpios property for
> these.
>
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - vdd-supply
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        dac@0 {
> > +            compatible = "microchip,mcp4821";
> > +            reg = <0>;
> > +            vdd-supply = <&vdd_regulator>;
> > +        };
> > +    };
> > --
> > 2.43.0
> >
> >