Re: [PATCH v1 1/2] dt-bindings: hwmon: Add starfive,jhb100-fan-tach

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The `tach-ch` property in the device tree example uses incorrect comma-separated syntax that evaluates to a 5-byte array rather than the intended 2-byte array.
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commit 4bf196984d444742e611042f289ee38d6b5ced8c
Author: Changhuang Liang <changhuang.liang@starfivetech.com>

dt-bindings: hwmon: Add starfive,jhb100-fan-tach

This commit adds the compatible string "starfive,jhb100-fan-tach" and the
corresponding binding schema for the StarFive JHB100 Fan-Tach controller.
The controller supports up to 16 fan tach inputs.

> diff --git a/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml b/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
[ ... ]
> +examples:
> +  - |
> +    fan-tach-controller@11be0000 {
> +        compatible = "starfive,jhb100-fan-tach";
> +        reg = <0x11be0000 0x400>;
> +        interrupts = <128>;
> +        clocks = <&per2crg 33>;
> +        resets = <&per2crg 5>;
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        fan@0 {
> +            reg = <0>;
> +            tach-ch = /bits/ 8 <0x0>, <0x8>;

Is the comma-separated syntax in tach-ch intentional? In Device Tree Source
syntax, the /bits/ 8 directive applies only to the immediately following
angle-bracket block.

Because tach-ch = /bits/ 8 <0x0>, <0x8>; separates the values with a comma,
the second block reverts to the default 32-bit cell size. This produces a
5-byte array [0x00, 0x00, 0x00, 0x00, 0x08] rather than the intended 2-byte
array.

If a developer copies this example into a real device tree, will the driver
incorrectly interpret it as 5 separate tachometer channels (0, 0, 0, 0, 8)
instead of the intended 2 channels (0, 8)?

Should this be written as /bits/ 8 <0x0 0x8>; or using byte array syntax
like [00 08] instead?

> +        };
> +        fan@1 {
> +            reg = <1>;
> +            tach-ch = /bits/ 8 <0x1>, <0x9>;
[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260428082337.743546-1-changhuang.liang@starfivetech.com?part=1