Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755272AbdGWKxp (ORCPT ); Sun, 23 Jul 2017 06:53:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:58224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752138AbdGWKxn (ORCPT ); Sun, 23 Jul 2017 06:53:43 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1966222B4B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=jic23@kernel.org Date: Sun, 23 Jul 2017 11:53:37 +0100 From: Jonathan Cameron To: Fabrice Gasnier Cc: , , , , , , , , , , , , , Subject: Re: [PATCH 2/3] dt-bindings: iio: adc: stm32: add optional min-sample-time Message-ID: <20170723115337.1e34e173@kernel.org> 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> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-unknown-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1739 Lines: 41 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 {