Re: [PATCH 2/3] dt-bindings: iio: adc: stm32: add optional min-sample-time

Jonathan Cameron
2017-07-23T10:53:45Z

On Tue, 18 Jul 2017 14:35:31 +0200
Fabrice Gasnier <fabrice.gasnier@st.com> wrote:

> STM32 ADC allows each channel to be sampled with a different sampling
> time. There's an application note that deals with this: 'How to get
> the best ADC accuracy in STM32...' It basically depends on analog input
> signal electrical properties (depends on board).
>
> Add optional 'min-sample-time' property so this can be tuned in dt.
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>

This isn't yet very standard, so I think it needs a manufacturer
prefix, e.g. st,min-sample-time. Also convention is I believe
to include the units as part of the naming where appropriate.

Hence st,min-sample-time-nsecs

Otherwise, seems good to me.

Jonathan
> ---
> Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
> index 8310073..9cd964b 100644
> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
> @@ -74,6 +74,11 @@ Optional properties:
> * can be 6, 8, 10 or 12 on stm32f4
> * can be 8, 10, 12, 14 or 16 on stm32h7
> Default is maximum resolution if unset.
> +- min-sample-time: Minimum sampling time in nanoseconds.
> + Depending on hardware (board) e.g. high/low analog input source impedance,
> + fine tune of ADC sampling time may be recommended.
> + This can be either one value or an array that matches 'st,adc-channels' list,
> + to set sample time resp. for all channels, or independently for each channel.
>
> Example:
> adc: adc@40012000 {