Hi,
Am Donnerstag, 2. Februar 2023, 18:10:52 CET schrieb Jonathan Cameron:
> On Wed, 1 Feb 2023 13:13:43 +0100
>
> Marco Felsch <m.felsch@xxxxxxxxxxxxxx> wrote:
> > 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.
Nice for pointing this out. I wasn't aware that there are differences.
> Oh goody. So is it detectable?
That's my problem. I didn't find any source of information which chips do
support multiple references and which don't.
Marco, do you have some information on this?
> If we are going to stick to a single compatible rather than adding them for
> the variants with and without this feature, should probably add a note at
> least to say it is required for some parts.
That's a good idea. I'm okay with that, until there is more information
available.
Best regards
Alexander
> Also, link if public would be good for purposes of discussion as my google
> fu didn't find relevant doc. (assuming it's public)
>
>
> Jonathan
>
> > 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 = <®_1v8>;
> > > > >
> > > > > #io-channel-cells = <1>;
> > > > >
> > > > > };
> > > > >
> > > > > };
