Re: [PATCH v3 2/3] dt-bindings: serial: maxim,max310x: describe per-channel rs485 subnodes

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Schema backward compatibility break for legacy multi-channel device trees by removing $refs to serial/rs485 schemas at the chip level.
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commit d832a7d0f42d71a0c331f81efe607eabea305da1
Author: Tapio Reijonen <tapio.reijonen@vaisala.com>

dt-bindings: serial: maxim,max310x: describe per-channel rs485 subnodes

This commit splits the binding for the MAX310x UART family, introducing
per-channel child nodes for multi-channel parts while keeping single-channel
parts as serial nodes. It removes the top-level serial and RS-485 references
and conditionally maps them based on the compatible string.

> diff --git a/Documentation/devicetree/bindings/serial/maxim,max310x.yaml b/Documentation/devicetree/bindings/serial/maxim,max310x.yaml
> index 889eeaca64a02..e598dda4d13f5 100644
> --- a/Documentation/devicetree/bindings/serial/maxim,max310x.yaml
> +++ b/Documentation/devicetree/bindings/serial/maxim,max310x.yaml
[ ... ]
> @@ -49,8 +56,55 @@ required:
>  
>  allOf:
>    - $ref: /schemas/spi/spi-peripheral-props.yaml#
> -  - $ref: /schemas/serial/serial.yaml#
> -  - $ref: /schemas/serial/rs485.yaml#
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - maxim,max3107
> +              - maxim,max3108
> +    then:
> +      allOf:
> +        - $ref: /schemas/serial/serial.yaml#
> +        - $ref: /schemas/serial/rs485.yaml#
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - maxim,max3109
> +              - maxim,max14830
> +    then:
> +      properties:

[Severity: Medium]
The commit message notes that existing users are unaffected because the driver
still reads chip-level RS-485 for single-channel and legacy device trees.

However, does this change break schema validation for legacy multi-channel
device trees?

By removing the top-level references to serial.yaml and rs485.yaml for
multi-channel parts, and because the binding uses unevaluatedProperties: false
at the top level, any legacy multi-channel device trees that still declare
serial or RS-485 properties at the chip level will now trigger unevaluated
property validation errors during dtbs_check.

Could we retain the top-level references for multi-channel parts, perhaps with
a deprecation note, to preserve ABI backward compatibility for existing device
trees?

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260615-b4-max310x-rs485-dt-v3-0-7e79f064bdd7@vaisala.com?part=2