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

From: Alexander Stein <alexander.stein@ew.tq-group.com>
To: Marco Felsch <m.felsch@pengutronix.de>
Cc: Cai Huoqing <cai.huoqing@linux.dev>,
	Haibo Chen <haibo.chen@nxp.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	devicetree@vger.kernel.org, linux-iio@vger.kernel.org,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] dt-bindings: iio: adc: add missing vref-supply
Date: Tue, 31 Jan 2023 13:14:00 +0100	[thread overview]
Message-ID: <1850476.tdWV9SEqCh@steina-w> (raw)
In-Reply-To: <20230131104816.w5sfpcdjulr2ogze@pengutronix.de>

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@ew.tq-group.com>
> > ---
> > 
> >  .../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.

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>;
> >          
> >          };
> >      
> >      };