Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751568AbdGXH4i (ORCPT ); Mon, 24 Jul 2017 03:56:38 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:57902 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750970AbdGXH4b (ORCPT ); Mon, 24 Jul 2017 03:56:31 -0400 Subject: Re: [PATCH 2/3] dt-bindings: iio: adc: stm32: add optional min-sample-time To: Jonathan Cameron CC: , , , , , , , , , , , , , References: <1500381332-17086-1-git-send-email-fabrice.gasnier@st.com> <1500381332-17086-3-git-send-email-fabrice.gasnier@st.com> <20170723115337.1e34e173@kernel.org> From: Fabrice Gasnier Message-ID: <81cabf83-689c-277a-5cf9-510df5cc9045@st.com> Date: Mon, 24 Jul 2017 09:55:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170723115337.1e34e173@kernel.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.75.127.51] X-ClientProxiedBy: SFHDAG2NODE3.st.com (10.75.127.6) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-24_06:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2306 Lines: 61 On 07/23/2017 12:53 PM, Jonathan Cameron wrote: > 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 Hi Jonathan, I originally used st,... form, when writing this patch, until I found out there's 'min-sample-time' in vf610 adc dt-bindings: - Documentation/devicetree/bindings/iio/adc/vf610-adc.txt It looks like to me very similar. I also agree it misses '-nsecs' units. Sure, I can use your suggestion above... Please can you just confirm if I should use same property as vf610 adc, or 'st,min-sample-time-nsecs' ? Thanks for reviewing, Best regards, Fabrice > > 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 { >