Re: [PATCH 1/8] dt-bindings: iio: adc: stm32-adc: add support for stm32mp23 and stm32mp25

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 15 Sep 2026 09:49:01 +0200
Fabrice Gasnier <fabrice.gasnier@foss.st.com> wrote:

> On 9/13/26 05:08, Jonathan Cameron wrote:
> > On Fri, 11 Sep 2026 17:51:23 +0200
> > Fabrice Gasnier <fabrice.gasnier@foss.st.com> wrote:
> >   
> >> Add stm32mp23 and stm32mp25 compatibles. Three ADCs can be found on
> >> these SoCs, split into two blocks:
> >> - ADC12 are tightly coupled (common registers).
> >> - ADC3 is managed independently.
> >> Each ADC is a 12-bits successive approximation analog-to-digital converter,
> >> with up to 20 multiplexed channels that can be configured as single ended
> >> or differential.
> >>
> >> New property "st,adc-trigger-sel " allow to make the difference between
> >> the ADCs and to apply the correct trigger configuration.
> >>
> >> STM32 ADC may be in a power domain: allow a single 'power-domains'.
> >>
> >> Restrict the last channel (19), as it is wired directly to ADC Vref+.
> >> It's meaningless to have direct measurement. Internal Vref with
> >> calibration data from bsec (nvmem) must be used instead e.g. vrefint.
> >> Restrict deprecated properties (st,adc-channels, st,adc-diff-channels,
> >> st,min-sample-time-nsecs).
> >>
> >> Co-developed-by: Cheick Traore <cheick.traore-ext@st.com>
> >> Signed-off-by: Cheick Traore <cheick.traore-ext@st.com>
> >> Co-developed-by: Olivier Moysan <olivier.moysan@foss.st.com>
> >> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
> >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>  
> > 
> > Hi Fabrice, all,
> >   
> >> ---
> >>  .../devicetree/bindings/iio/adc/st,stm32-adc.yaml  | 106 ++++++++++++++++++---
> >>  1 file changed, 94 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
> >> index c4c4575d3fa9..0e0ceaa3d8d6 100644
> >> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
> >> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
> >> @@ -23,11 +23,18 @@ maintainers:
> >>  
> >>  properties:
> >>    compatible:
> >> -    enum:
> >> -      - st,stm32f4-adc-core
> >> -      - st,stm32h7-adc-core
> >> -      - st,stm32mp1-adc-core
> >> -      - st,stm32mp13-adc-core
> >> +    oneOf:
> >> +      - items:
> >> +          - enum:
> >> +              - st,stm32f4-adc-core
> >> +              - st,stm32h7-adc-core
> >> +              - st,stm32mp1-adc-core
> >> +              - st,stm32mp13-adc-core
> >> +      - items:
> >> +          - enum:
> >> +              - st,stm32mp23-adc-core
> >> +              - st,stm32mp25-adc-core
> >> +          - const: st,stm32-adc-core  
> > 
> > What is this?  Given these all vary in features
> > why would we fallback to a generic match for
> > these new compatibles?  
> 
> Hi Jonathan, all
> 
> Ack, I'll drop it in v2,
> 
> > 
> > 
> >   
> >>  additionalProperties: false
> >>  
> >>  required:
> >> @@ -239,11 +276,18 @@ patternProperties:
> >>  
> >>      properties:
> >>        compatible:
> >> -        enum:
> >> -          - st,stm32f4-adc
> >> -          - st,stm32h7-adc
> >> -          - st,stm32mp1-adc
> >> -          - st,stm32mp13-adc
> >> +        oneOf:
> >> +          - items:
> >> +              - enum:
> >> +                  - st,stm32f4-adc
> >> +                  - st,stm32h7-adc
> >> +                  - st,stm32mp1-adc
> >> +                  - st,stm32mp13-adc
> >> +          - items:
> >> +              - enum:
> >> +                  - st,stm32mp23-adc
> >> +                  - st,stm32mp25-adc
> >> +              - const: st,stm32-adc  
> > 
> > Similar to above, what is this?  
> 
> same,
> 
> > 
> >   
> >> @@ -344,6 +388,12 @@ patternProperties:
> >>          items:
> >>            - const: vrefint
> >>  
> >> +      st,adc-trigger-sel:
> >> +        description: Selects the HW trigger configuration available on this ADC
> >> +        $ref: /schemas/types.yaml#/definitions/uint32
> >> +        enum: [0, 1]  
> > 
> > Magic value that is meaningless to see in a dts.  If they
> > are effectively not compatible, give them different compatibles and
> > drop this property.  I'm unconvinced this property is more
> > useful than that given just how opaque the description is.  
> 
> That's exactly what I was wondering about. As you suggest, I can remove
> this property, and introduce dedicated compatibles in V2, to clearly
> identify the differences.
> 
> Need to distinguish:
> - ADC12 are tightly coupled (common registers).
> - ADC3 is managed independently.
> Triggers are different between them. The purpose of st,adc-trigger-sel
> was to identify that.
> 
> Also MP23 and MP25 are also different (trigger list). Combining this
> would lead to introduce four compatibles, I'm thinking of:
> - st,stm32mp23-adc12
> - st,stm32mp23-adc3
> - st,stm32mp25-adc12
> - st,stm32mp25-adc3
> 
Naming wise, I wonder if it looks too much like adc twelve?
Not sure how to avoid that cleanly as adc1-2 seems odd too.

> I plan to update it in v2.
> 
> Thanks,
> Fabrice
> 
> > 
> > 
> >   
>