From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Subject: Re: [PATCH 2/3] dt-bindings: iio: adc: stm32: add optional min-sample-time Date: Sun, 23 Jul 2017 11:53:37 +0100 Message-ID: <20170723115337.1e34e173@kernel.org> References: <1500381332-17086-1-git-send-email-fabrice.gasnier@st.com> <1500381332-17086-3-git-send-email-fabrice.gasnier@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1500381332-17086-3-git-send-email-fabrice.gasnier-qxv4g6HH51o@public.gmane.org> Sender: linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Fabrice Gasnier Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, mcoquelin.stm32-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, alexandre.torgue-qxv4g6HH51o@public.gmane.org, lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org, knaack.h-Mmb7MZpHnFY@public.gmane.org, pmeerw-jW+XmwGofnusTnJN9+BGXg@public.gmane.org, benjamin.gaignard-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, benjamin.gaignard-qxv4g6HH51o@public.gmane.org, linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.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@40012000 {