linux-kernel - Re: [PATCH 1/3] dt-bindings: iio: dac: Add max22007

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Message-ID: <7ea6cb11-b9a7-4944-bfa1-63c063eb421e@kernel.org>
Date: Fri, 19 Dec 2025 16:50:47 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Janani Sunil <janani.sunil@...log.com>,
 Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 Alexandru Ardelean <alexandru.ardelean@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Jonathan Corbet <corbet@....net>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: iio: dac: Add max22007

On 19/12/2025 16:31, Janani Sunil wrote:
> Devicetree bindings for MAX22007 4-channel
> 12-bit DAC that drives a voltage or current
> output on each channel

Please wrap commit message according to Linux coding style / submission
process (neither too early nor over the limit):
https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597

> 
> Signed-off-by: Janani Sunil <janani.sunil@...log.com>
> ---
>  .../devicetree/bindings/iio/dac/adi,max22007.yaml  | 116 +++++++++++++++++++++
>  MAINTAINERS                                        |   7 ++
>  2 files changed, 123 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml b/Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
> new file mode 100644
> index 000000000000..c2f65d9e42d4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
> @@ -0,0 +1,116 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/dac/adi,max22007.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices MAX22007 DAC device driver

Bindings are for hardware, drop all device driver references.

> +
> +maintainers:
> +  - Janani Sunil <janani.sunil@...log.com>
> +
> +description:
> +  The MAX22007 is a quad-channel, 12-bit digital-to-analog converter (DAC)
> +  with integrated precision output amplifiers and current output capability.
> +  Each channel can be independently configured for voltage or current output.
> +  Datasheet available at https://www.analog.com/en/products/max22007.html
> +
> +$ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +properties:
> +  compatible:
> +    const: adi,max22007
> +
> +  reg:
> +    maxItems: 1
> +
> +  spi-max-frequency:
> +    maximum: 500000
> +
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +  vdd-supply:
> +    description: Low-Voltage Power Supply from +2.7V to +5.5V.
> +
> +  hvdd-supply:
> +    description:
> +      Positive High-Voltage Power Supply from +8V to (HVSS +24V) for
> +      the Output Channels.
> +
> +  hvss-supply:
> +    description:
> +      Negative High-Voltage Power Supply from -2V to 0V for the Output Channels.
> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO used for hardware reset of the device.

Drop description, redundant, because not saying anything other than
schema already said. You could say whether it is active low for example
if you wanted to add something useful.

> +
> +patternProperties:
> +  "^channel@[0-3]$":
> +    allOf:
> +      - $ref: /schemas/iio/dac/dac.yaml#
> +      - type: object

Drop allOf. I don't get where did you get this syntax, it's not needed.

> +        description:
> +          Represents the external channels which are connected to the DAC.
> +          Channels not specified in the device tree will be powered off.
> +
> +        properties:
> +          reg:
> +            description: Channel number
> +            maxItems: 1
> +
> +          adi,type:
> +            description: Channel output type.
> +            $ref: /schemas/types.yaml#/definitions/string
> +            enum: [voltage, current]

Why would it matter if this is voltage or current? That's the first time
this property appears. Why none of existing fit?

> +
> +        required:
> +          - reg
> +          - adi,type
> +
> +        unevaluatedProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +
> +anyOf:
> +  - required: [channel@0]
> +  - required: [channel@1]
> +  - required: [channel@2]
> +  - required: [channel@3]
> +
> +unevaluatedProperties: false


Best regards,
Krzysztof