Re: [PATCH v5 1/4] dt-bindings: iio: adc: Add ltc2378

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 3 Jul 2026 14:04:51 -0300
Marcelo Schmitt <marcelo.schmitt1@gmail.com> wrote:

> On 07/02, sashiko-bot@kernel.org wrote:
> > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> > - [Low] Compatible strings with required fallbacks are incorrectly allowed as standalone strings.
> > --
> > 
> > commit fff47614872c95c6a481f63da8b14dfcedd0bb53
> > Author: Marcelo Schmitt <marcelo.schmitt@analog.com>
> > 
> > dt-bindings: iio: adc: Add ltc2378
> > 
> > Document how to describe LTC2378-20 and similar ADCs in device tree.
> >   
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ltc2378.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ltc2378.yaml
> > > new file mode 100644
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ltc2378.yaml  
> > [ ... ]  
> > > +properties:
> > > +  compatible:
> > > +    oneOf:
> > > +      # Single compatible string match.
> > > +      - enum:
> > > +          - adi,ltc2338-18
> > > +          - adi,ltc2364-16
> > > +          - adi,ltc2364-18
> > > +          - adi,ltc2367-16
> > > +          - adi,ltc2367-18
> > > +          - adi,ltc2368-16
> > > +          - adi,ltc2368-18
> > > +          - adi,ltc2369-18
> > > +          - adi,ltc2370-16  
> > 
> > [Severity: Low]
> > Does this standalone enum allow devices that should require a fallback
> > to pass schema validation with only a single compatible string?
> > 
> > Because parts like "adi,ltc2370-16" and "adi,ltc2367-16" are listed here in
> > the single enum match, a device tree node specifying only
> > compatible = "adi,ltc2370-16" will satisfy this block and successfully pass
> > schema validation.
> > 
> > This seems to bypass the fallback requirements defined below in the items
> > blocks:
> > 
> > [ ... ]  
> > > +      # Low sample rate fallback for 16-bit unipolar sensors.
> > > +      - items:
> > > +          - enum:
> > > +              - adi,ltc2370-16 # 2 MSPS
> > > +              - adi,ltc2368-16 # 1 MSPS
> > > +              - adi,ltc2367-16 # 500 kSPS
> > > +          - const: adi,ltc2364-16 # fallback (250 kSPS)  
> > 
> > Should the parts that require a fallback be removed from the single
> > compatible string enum so the schema correctly enforces the fallback?  
> 
> Why? Should users be prevented to specify a single specific compatible string?
Yes we should. They should always use the double string to provide a fallback.

In practice the driver will work just fine with only a single entry irrespective
of what the binding doc says - that doesn't change that we insist on it in the binding
doc.

Jonathan