Re: [PATCH v2 1/1] dt-bindings: iio: imx8qxp-adc: add missing vref-supply

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 24 Apr 2023 11:23:12 +0200
Alexander Stein <alexander.stein@ew.tq-group.com> 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@ew.tq-group.com>

Interesting that we are talking her only about vrefh, what about vrefp?
I guess the assumption is that will be wired to 0V?

The first reference I found didn't seem to imply that was necessarily the
case. https://www.mouser.com/pdfDocs/IMX8QXPAEC.pdf


Jonathan

> ---
> Thanks for your inputs. This improved descritpion should make it clear
> that this property is only about the external reference voltage, not
> about the optional, internal voltages.
> 
> Changes in v2:
> * Improved commit message subject as suggested
> * Add hint about feature flag regarding multiple, internal, reference
>   voltages
> 
>  .../devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml       | 7 +++++++
>  1 file changed, 7 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..878e67054d7c 100644
> --- a/Documentation/devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/nxp,imx8qxp-adc.yaml
> @@ -39,6 +39,12 @@ properties:
>    power-domains:
>      maxItems: 1
>  
> +  vref-supply:
> +    description: |
> +      External ADC reference voltage supply on VREFH pad. If VERID[MVI] is
> +      set, there are additional, internal reference voltages selectable.
> +      VREFH1 is always from VREFH pad.
> +
>    "#io-channel-cells":
>      const: 1
>  
> @@ -72,6 +78,7 @@ 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>;
>          };
>      };