From patchwork Mon Jul 24 16:10:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabrice Gasnier X-Patchwork-Id: 9859781 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 556FA60349 for ; Mon, 24 Jul 2017 16:22:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4725127F86 for ; Mon, 24 Jul 2017 16:22:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3C27D284F4; Mon, 24 Jul 2017 16:22:35 +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,RCVD_IN_DNSWL_NONE autolearn=unavailable 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 59FE0284AF for ; Mon, 24 Jul 2017 16:22:33 +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=sgQp6ni2owaIEkXRY4zxIk1MpJLZFNcmySp+tnB1DqI=; b=DFRES4kBU6SFrS Xyvr83c5KeVV/c0368vUj/K0F8vk4LMcM/hNoathkfywFi56PIvHafcbxsiYl0giqi1wlM5RZ+Zii YVgsoHdIhokaZj9d8bPoeSK7boZJpnTVZAezPw10RLZ9RVqSbzqgaMt9SkG66ePvTmekvIymJn/CO Xk5GG/HFwrzciQ62L3wUhrdWG17RiqNW+3p7XjZ9Wceehc1o9gGEFBvjmjjwp3luX/Cl/2TdxlaCh 74GpX1c18GyWzutbGtyX6GOOrpTapC4sZz2Vl8ry+Hu/hJjZZg5AUhr1iGFe7wdP6kpcTwS0hJkrU M9Sqqljo55K2cT8XNoPw==; 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 1dZg7s-0007rE-N0; Mon, 24 Jul 2017 16:22:32 +0000 Received: from mx08-00178001.pphosted.com ([91.207.212.93] helo=mx07-00178001.pphosted.com) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dZfy8-0002VU-MU for linux-arm-kernel@lists.infradead.org; Mon, 24 Jul 2017 16:12:31 +0000 Received: from pps.filterd (m0046660.ppops.net [127.0.0.1]) by mx08-.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6OG8mkJ004588; Mon, 24 Jul 2017 18:11:52 +0200 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx08-.pphosted.com with ESMTP id 2buuu4uk8n-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 24 Jul 2017 18:11:52 +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 3E8D334; Mon, 24 Jul 2017 16:11:52 +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 0F7ED2A2B; 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 18:11:51 +0200 From: Fabrice Gasnier To: , Subject: [PATCH v2 1/3] iio: adc: stm32: fix common clock rate Date: Mon, 24 Jul 2017 18:10:38 +0200 Message-ID: <1500912640-23927-2-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: SFHDAG5NODE3.st.com (10.75.127.15) 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170724_091229_576857_4B57441E X-CRM114-Status: UNSURE ( 9.84 ) 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, 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 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 Fixes: 95e339b6e85d ("iio: adc: stm32: add support for STM32H7") ADC clock input is provided to internal prescaler (that decreases its frequency). It's then used as reference clock for conversions. - Fix common clock rate used then by stm32-adc sub-devices. Take common prescaler into account. Currently, rate is used to set "boost" mode. It may unnecessarily be set. This impacts power consumption. - Fix ADC max clock rate on STM32H7 (fADC from datasheet). Currently, prescaler may be set too low. This can result in ADC reference clock used for conversion to exceed max allowed clock frequency. Signed-off-by: Fabrice Gasnier --- Changes in v2: - Better description of wrong things being fixed. --- drivers/iio/adc/stm32-adc-core.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c index e09233b..6096763 100644 --- a/drivers/iio/adc/stm32-adc-core.c +++ b/drivers/iio/adc/stm32-adc-core.c @@ -64,7 +64,7 @@ #define STM32H7_CKMODE_MASK GENMASK(17, 16) /* STM32 H7 maximum analog clock rate (from datasheet) */ -#define STM32H7_ADC_MAX_CLK_RATE 72000000 +#define STM32H7_ADC_MAX_CLK_RATE 36000000 /** * stm32_adc_common_regs - stm32 common registers, compatible dependent data @@ -148,14 +148,14 @@ static int stm32f4_adc_clk_sel(struct platform_device *pdev, return -EINVAL; } - priv->common.rate = rate; + priv->common.rate = rate / stm32f4_pclk_div[i]; val = readl_relaxed(priv->common.base + STM32F4_ADC_CCR); val &= ~STM32F4_ADC_ADCPRE_MASK; val |= i << STM32F4_ADC_ADCPRE_SHIFT; writel_relaxed(val, priv->common.base + STM32F4_ADC_CCR); dev_dbg(&pdev->dev, "Using analog clock source at %ld kHz\n", - rate / (stm32f4_pclk_div[i] * 1000)); + priv->common.rate / 1000); return 0; } @@ -250,7 +250,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, out: /* rate used later by each ADC instance to control BOOST mode */ - priv->common.rate = rate; + priv->common.rate = rate / div; /* Set common clock mode and prescaler */ val = readl_relaxed(priv->common.base + STM32H7_ADC_CCR); @@ -260,7 +260,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, writel_relaxed(val, priv->common.base + STM32H7_ADC_CCR); dev_dbg(&pdev->dev, "Using %s clock/%d source at %ld kHz\n", - ckmode ? "bus" : "adc", div, rate / (div * 1000)); + ckmode ? "bus" : "adc", div, priv->common.rate / 1000); return 0; }