Re: [PATCH v3 1/2] dt-bindings: iio: dac: add support for mcp47a1

On Mon, 03 Aug 2026 18:07:16 +0000
[email protected] wrote:

> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [Medium] The I2C addresses specified in the schema and example appear to be 8-bit write addresses instead of the 7-bit addresses required by the DT specification.
> - [Low] The `reg` property schema applies an integer `enum` directly to a matrix array element, which will cause `dt_binding_check` validation to always fail.
> --
> 
> --- Patch [1]: [PATCH v3 1/2] dt-bindings: iio: dac: add support for mcp47a1 ---
> commit 441e840b5a2a3f037c3520c49013a55b7dc4c1bd
> Author: Joshua Crofts <[email protected]>
> 
> dt-bindings: iio: dac: add support for mcp47a1
> 
> The Microchip MCP47A1 is a 6-bit volatile Digital-to-Analog converter
> which communicates via I2C.
> 
> > diff --git a/Documentation/devicetree/bindings/iio/dac/microchip,mcp47a1.yaml b/Documentation/devicetree/bindings/iio/dac/microchip,mcp47a1.yaml
> > new file mode 100644
> > index 0000000000000..b181fe73dce84
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/dac/microchip,mcp47a1.yaml  
> [ ... ]
> > +properties:
> > +  compatible:
> > +    const: microchip,mcp47a1
> > +
> > +  reg:
> > +    items:
> > +      - enum: [0x2e, 0x3e]  
> 
> [Severity: Low]
> Will this cause dt_binding_check validation to fail?

No, this is a perfectly valid dt-schema which passes dt_binding_check.

> 
> Since dt-schema parses reg values into a uint32-matrix (an array of arrays),
> the items array applied to it defines a tuple schema for the outer array's
> elements. This means the inner array [0x2e] will be matched against the
> integer enum [0x2e, 0x3e], which will mathematically fail since an array
> is not an integer.
> 
> [Severity: Medium]
> Are these 8-bit write addresses instead of the 7-bit addresses required by
> the Device Tree specification?
> 
> If these are indeed 8-bit addresses (as indicated by the 0 LSB and typical
> Microchip datasheet conventions), they must be shifted right by 1. That would
> make the correct 7-bit DT addresses 0x17 and 0x1f.

No clue what Sashiko is on about since these are indeed 7-bit addresses which
do work when tested on the actual hardware.

-- 
Kind regards,
Joshua Crofts