From mboxrd@z Thu Jan 1 00:00:00 1970 From: jic23@kernel.org (Jonathan Cameron) Date: Sun, 23 Jul 2017 11:53:37 +0100 Subject: [PATCH 2/3] dt-bindings: iio: adc: stm32: add optional min-sample-time In-Reply-To: <1500381332-17086-3-git-send-email-fabrice.gasnier@st.com> References: <1500381332-17086-1-git-send-email-fabrice.gasnier@st.com> <1500381332-17086-3-git-send-email-fabrice.gasnier@st.com> Message-ID: <20170723115337.1e34e173@kernel.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 18 Jul 2017 14:35:31 +0200 Fabrice Gasnier 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 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 at 40012000 {