From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A834AC43381 for ; Mon, 25 Mar 2019 14:25:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 825EA2084D for ; Mon, 25 Mar 2019 14:25:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729568AbfCYOZI (ORCPT ); Mon, 25 Mar 2019 10:25:08 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:14221 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726194AbfCYOZG (ORCPT ); Mon, 25 Mar 2019 10:25:06 -0400 Received: from pps.filterd (m0046668.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2PEL0C4019417; Mon, 25 Mar 2019 15:24:20 +0100 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 2rddhbbr65-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 25 Mar 2019 15:24:20 +0100 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 6A4AC31; Mon, 25 Mar 2019 14:24:19 +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 3C6CAA493; Mon, 25 Mar 2019 14:24:19 +0000 (GMT) Received: from localhost (10.75.127.45) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 25 Mar 2019 15:24:18 +0100 From: Fabrice Gasnier To: CC: , , , , , , , , , , , Subject: [PATCH] iio: adc: stm32-dfsdm: improve sampling frequency accuracy Date: Mon, 25 Mar 2019 15:24:01 +0100 Message-ID: <1553523841-16315-1-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.75.127.45] X-ClientProxiedBy: SFHDAG8NODE2.st.com (10.75.127.23) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-25_09:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The sample frequency is driven using the oversampling ratio depending on the SPI bus frequency. Currently, oversampling ratio is computed by an entire division: - spi_freq / sample_freq. This may result in inaccurate value. Using DIV_ROUND_CLOSEST improves resulting sample frequency, which is useful for audio that requests fixed rates (such as: 8, 16 or 32 kHz). BTW, introduce new routine to re-factor sample frequency setting, and move frequency accuracy message from warning to debug level. Signed-off-by: Fabrice Gasnier --- drivers/iio/adc/stm32-dfsdm-adc.c | 56 +++++++++++++++++++++------------------ 1 file changed, 30 insertions(+), 26 deletions(-) diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c index 531ca7e..051561c 100644 --- a/drivers/iio/adc/stm32-dfsdm-adc.c +++ b/drivers/iio/adc/stm32-dfsdm-adc.c @@ -558,13 +558,38 @@ static ssize_t dfsdm_adc_audio_get_spiclk(struct iio_dev *indio_dev, return snprintf(buf, PAGE_SIZE, "%d\n", adc->spi_freq); } +static int dfsdm_adc_set_samp_freq(struct iio_dev *indio_dev, + unsigned int sample_freq, + unsigned int spi_freq) +{ + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); + struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id]; + unsigned int oversamp; + int ret; + + oversamp = DIV_ROUND_CLOSEST(spi_freq, sample_freq); + if (spi_freq % sample_freq) + dev_dbg(&indio_dev->dev, + "Rate not accurate. requested (%u), actual (%u)\n", + sample_freq, spi_freq / oversamp); + + ret = stm32_dfsdm_set_osrs(fl, 0, oversamp); + if (ret < 0) { + dev_err(&indio_dev->dev, "No filter parameters that match!\n"); + return ret; + } + adc->sample_freq = spi_freq / oversamp; + adc->oversamp = oversamp; + + return 0; +} + static ssize_t dfsdm_adc_audio_set_spiclk(struct iio_dev *indio_dev, uintptr_t priv, const struct iio_chan_spec *chan, const char *buf, size_t len) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); - struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id]; struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[chan->channel]; unsigned int sample_freq = adc->sample_freq; unsigned int spi_freq; @@ -583,17 +608,9 @@ static ssize_t dfsdm_adc_audio_set_spiclk(struct iio_dev *indio_dev, return -EINVAL; if (sample_freq) { - if (spi_freq % sample_freq) - dev_warn(&indio_dev->dev, - "Sampling rate not accurate (%d)\n", - spi_freq / (spi_freq / sample_freq)); - - ret = stm32_dfsdm_set_osrs(fl, 0, (spi_freq / sample_freq)); - if (ret < 0) { - dev_err(&indio_dev->dev, - "No filter parameters that match!\n"); + ret = dfsdm_adc_set_samp_freq(indio_dev, sample_freq, spi_freq); + if (ret < 0) return ret; - } } adc->spi_freq = spi_freq; @@ -1068,22 +1085,9 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev, spi_freq = adc->spi_freq; } - if (spi_freq % val) - dev_warn(&indio_dev->dev, - "Sampling rate not accurate (%d)\n", - spi_freq / (spi_freq / val)); - - ret = stm32_dfsdm_set_osrs(fl, 0, (spi_freq / val)); - if (ret < 0) { - dev_err(&indio_dev->dev, - "Not able to find parameter that match!\n"); - iio_device_release_direct_mode(indio_dev); - return ret; - } - adc->sample_freq = val; + ret = dfsdm_adc_set_samp_freq(indio_dev, val, spi_freq); iio_device_release_direct_mode(indio_dev); - - return 0; + return ret; } return -EINVAL; -- 2.7.4