From patchwork Tue Jul 18 12:35:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabrice Gasnier X-Patchwork-Id: 9848271 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E848A600CC for ; Tue, 18 Jul 2017 12:37:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D9A6C28550 for ; Tue, 18 Jul 2017 12:37:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CE48C28575; Tue, 18 Jul 2017 12:37:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 250D628550 for ; Tue, 18 Jul 2017 12:37:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RtEzlZsiUr1+JDXfjIfaaw03Sd19EStcZqNPTKkITCQ=; b=bxbYMS8OW2Py2b sfIs4oZ1htDVf6dkiR8Fgg9bh3Mos77BoyZ8HAqmKIr/O76hGxV36utYaiYLsbtN+xMs3qDR1Od84 WdNUMcKaf3ufrw5jQY4Ywjjc5a8z3+nqPacoTgf96nlZ5pXnW2e1sLuuMOIQoe2QvbTBsw7cBQPsU ECXn2T/0XKriy1BWj1necI7Ol025DaA6+uvDCdzaegrWAYlYPkIuQ+odQfGoVJvxOjJHyn8oskzLz BtnMtakZY4K8MtBt7hHjXg/JgHicybsw7Y6W0hYqNbUm1kwOrrdizN77CbQiqeluqt3IQ8rV5IIBX 9/2qIbbBChEdxwZgxZvw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dXRl1-0003up-8V; Tue, 18 Jul 2017 12:37:43 +0000 Received: from mx07-00178001.pphosted.com ([62.209.51.94]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dXRkN-0003Mi-Mk for linux-arm-kernel@lists.infradead.org; Tue, 18 Jul 2017 12:37:06 +0000 Received: from pps.filterd (m0046037.ppops.net [127.0.0.1]) by mx07-.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6ICXqpY007054; Tue, 18 Jul 2017 14:36:21 +0200 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-.pphosted.com with ESMTP id 2brshhf5bc-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Tue, 18 Jul 2017 14:36:21 +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 1055838; Tue, 18 Jul 2017 12:36:21 +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 D4D632438; Tue, 18 Jul 2017 12:36:20 +0000 (GMT) Received: from localhost (10.75.127.50) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1178.4; Tue, 18 Jul 2017 14:36:20 +0200 From: Fabrice Gasnier To: , Subject: [PATCH 2/3] dt-bindings: iio: adc: stm32: add optional min-sample-time Date: Tue, 18 Jul 2017 14:35:31 +0200 Message-ID: <1500381332-17086-3-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1500381332-17086-1-git-send-email-fabrice.gasnier@st.com> References: <1500381332-17086-1-git-send-email-fabrice.gasnier@st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.50] X-ClientProxiedBy: SFHDAG3NODE2.st.com (10.75.127.8) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-07-18_04:, , signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170718_053704_067423_648EF3CF X-CRM114-Status: UNSURE ( 5.85 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, benjamin.gaignard@linaro.org, lars@metafoo.de, alexandre.torgue@st.com, linux-iio@vger.kernel.org, pmeerw@pmeerw.net, linux@armlinux.org.uk, linux-kernel@vger.kernel.org, mcoquelin.stm32@gmail.com, knaack.h@gmx.de, fabrice.gasnier@st.com, linux-arm-kernel@lists.infradead.org, benjamin.gaignard@st.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- 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 {