Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754324AbdG3QTn (ORCPT ); Sun, 30 Jul 2017 12:19:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:58810 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754159AbdG3QTk (ORCPT ); Sun, 30 Jul 2017 12:19:40 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DBF9622C86 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 17:19:35 +0100 From: Jonathan Cameron To: Fabrice Gasnier Cc: , , , , , , , , , , , Subject: Re: [PATCH v2 1/3] iio: adc: stm32: fix common clock rate Message-ID: <20170730171935.7b6adfca@kernel.org> In-Reply-To: <1500912640-23927-2-git-send-email-fabrice.gasnier@st.com> References: <1500912640-23927-1-git-send-email-fabrice.gasnier@st.com> <1500912640-23927-2-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: 2818 Lines: 76 On Mon, 24 Jul 2017 18:10:38 +0200 Fabrice Gasnier wrote: > 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 I've applied this one to the fixes togreg branch of iio.git. Thanks, Jonathan > --- > 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; > }