Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754251AbdG3QYZ (ORCPT ); Sun, 30 Jul 2017 12:24:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:59774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754159AbdG3QYX (ORCPT ); Sun, 30 Jul 2017 12:24:23 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C26B22BCD 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, 30 Jul 2017 17:24:17 +0100 From: Jonathan Cameron To: Fabrice Gasnier Cc: , , , , , , , , , , , Subject: Re: [PATCH v2 2/3] dt-bindings: iio: adc: stm32: add optional st,min-sample-time-nsecs Message-ID: <20170730172417.5c3d38bb@kernel.org> In-Reply-To: <1500912640-23927-3-git-send-email-fabrice.gasnier@st.com> References: <1500912640-23927-1-git-send-email-fabrice.gasnier@st.com> <1500912640-23927-3-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: 1914 Lines: 47 On Mon, 24 Jul 2017 18:10:39 +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 'st,min-sample-time-nsecs' property so this can be tuned > in dt. > > Signed-off-by: Fabrice Gasnier This ideally wants a devicetree review so I'm going to sit on it for a few days longer. Looks fine to me as does the implementation patch. Give me a kick in a week or so if we have seen no progress on this. I will be travelling from next weekend and access may be a little intermittent for up to two weeks. Thanks, Jonathan > --- > Changes in v2: > - Use 'st,min-sample-time-nsecs' instead of 'min-sample-time'. > --- > 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..48bfcaa3 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. > +- st,min-sample-time-nsecs: 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 {