From patchwork Mon Jul 24 16:10:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabrice Gasnier X-Patchwork-Id: 792874 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=devicetree-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3xGRHj4FNKz9s75 for ; Tue, 25 Jul 2017 02:13:21 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932339AbdGXQMt (ORCPT ); Mon, 24 Jul 2017 12:12:49 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:32271 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932135AbdGXQMo (ORCPT ); Mon, 24 Jul 2017 12:12:44 -0400 Received: from pps.filterd (m0046668.ppops.net [127.0.0.1]) by mx07-.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6OG8w68004690; Mon, 24 Jul 2017 18:11:53 +0200 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-.pphosted.com with ESMTP id 2buv5wb5jh-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 24 Jul 2017 18:11:53 +0200 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 064C931; Mon, 24 Jul 2017 16:11:53 +0000 (GMT) Received: from Webmail-eu.st.com (sfhdag5node3.st.com [10.75.127.15]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id D1B972A2D; Mon, 24 Jul 2017 16:11:52 +0000 (GMT) Received: from localhost (10.75.127.46) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1178.4; Mon, 24 Jul 2017 18:11:52 +0200 From: Fabrice Gasnier To: , CC: , , , , , , , , , , , Subject: [PATCH v2 2/3] dt-bindings: iio: adc: stm32: add optional st, min-sample-time-nsecs Date: Mon, 24 Jul 2017 18:10:39 +0200 Message-ID: <1500912640-23927-3-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1500912640-23927-1-git-send-email-fabrice.gasnier@st.com> References: <1500912640-23927-1-git-send-email-fabrice.gasnier@st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG1NODE3.st.com (10.75.127.3) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-07-24_11:, , signatures=0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org 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 Acked-by: Rob Herring --- 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 {