Re: [PATCH 1/1] dt-bindings: iio: adc: add missing vref-supply

[Marco Felsch <m.felsch@xxxxxxxxxxxxxx>]

Hi Alexander,

On 23-01-31, Alexander Stein wrote:
> Hi Marco,
> 
> thanks for the feedback.
> 
> Am Dienstag, 31. Januar 2023, 11:48:16 CET schrieb Marco Felsch:
> > Hi Alexander,
> > 
> > On 23-01-31, Alexander Stein wrote:
> > > Although this property is used right now for IIO_CHAN_INFO_SCALE,
> > > this ADC has two internal reference voltages, which the driver currently
> > > doesn't make use of.
> > > 
> > > Fixes: db73419d8c06 ("dt-bindings: iio: adc: Add binding documentation for
> > > NXP IMX8QXP ADC") Signed-off-by: Alexander Stein
> > > <alexander.stein@xxxxxxxxxxxxxxx>
> > > ---
> > > 
> > >  .../devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml          | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git
> > > a/Documentation/devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml
> > > b/Documentation/devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml index
> > > 63369ba388e4..879768af0303 100644
> > > --- a/Documentation/devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml
> > > +++ b/Documentation/devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml
> > > 
> > > @@ -39,6 +39,9 @@ properties:
> > >    power-domains:
> > >      maxItems: 1
> > > 
> > > +  vref-supply:
> > > +    description: External ADC reference voltage supply on VREFH pad.
> > 
> > Please add it to the list of required properties, we can remove it as
> > soon as the driver has support for the internal reference voltages.
> 
> I was thinking in doing so before as well. But DT describes the hardware, and 
> this ADC apparently would be functioning without a reference voltage on that 
> pad, using a different one. What the driver actual does is a different matter.

I have also thought about it first but than I checked the RM which says
that "multi-reference selection" is chip dependent.

Regards,
  Marco


> 
> Best regards,
> Alexander
> 
> > Regards,
> >   Marco
> > 
> > > +
> > > 
> > >    "#io-channel-cells":
> > >      const: 1
> > > 
> > > @@ -72,6 +75,7 @@ examples:
> > >              assigned-clocks = <&clk IMX_SC_R_ADC_0>;
> > >              assigned-clock-rates = <24000000>;
> > >              power-domains = <&pd IMX_SC_R_ADC_0>;
> > > 
> > > +            vref-supply = <&reg_1v8>;
> > > 
> > >              #io-channel-cells = <1>;
> > >          
> > >          };
> > >      
> > >      };
> 
> 
> 
> 
>