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[209.132.180.67]) by mx.google.com with ESMTP id p13si15559085plo.33.2019.06.19.06.04.52; Wed, 19 Jun 2019 06:05:14 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@st.com header.s=STMicroelectronics header.b=0xenS9bc; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731925AbfFSNEf (ORCPT + 99 others); Wed, 19 Jun 2019 09:04:35 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:63798 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731894AbfFSNEe (ORCPT ); Wed, 19 Jun 2019 09:04:34 -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 x5JCu1vs023624; Wed, 19 Jun 2019 15:04:03 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=STMicroelectronics; bh=1RIed4PSnLNoF/Qg8Sp7JJ0Sajo64o3gdxbSWUs/b4M=; b=0xenS9bcGVcF8713j77nhv9uVF0N+3rssP3bIA4M00CmyUSAdrwem78TNJJNHfTMdReb hibMRJP0HII90WclTnhXFen799MWDD/raHoZnqsHbOBbPWUJFplV8tYCsdK8h7BOWAgB xk1FVwbkGYx828MwMagijwfaNOg1olBktgZfIZ5utfW8B/d5l+iFdSI+juK5e5c9iuKR x4dpT76VUixZ5pa0Yz+5LRtRPnSyXKu7GCWx+etdZhJt7Ei2O0LF3lXSLgV/jD/V4e1U Rs27nGZcFT54Z0W4601g8h6Ui5MHlqxcEanwRD+C6rqGePLtRs9XHJiNAg7pWbj8FW+J cA== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 2t7813c0aq-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Wed, 19 Jun 2019 15:04:03 +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 DC7D638; Wed, 19 Jun 2019 13:04:02 +0000 (GMT) Received: from Webmail-eu.st.com (Safex1hubcas23.st.com [10.75.90.46]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id B5A452834; Wed, 19 Jun 2019 13:04:02 +0000 (GMT) Received: from SAFEX1HUBCAS21.st.com (10.75.90.45) by SAFEX1HUBCAS23.st.com (10.75.90.46) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 19 Jun 2019 15:04:02 +0200 Received: from localhost (10.201.23.16) by Webmail-ga.st.com (10.75.90.48) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 19 Jun 2019 15:04:02 +0200 From: Olivier Moysan To: , , , , , , , , , , , , Subject: [PATCH 5/5] iio: adc: stm32-dfsdm: add comment for 16 bits record Date: Wed, 19 Jun 2019 15:03:51 +0200 Message-ID: <1560949431-22948-6-git-send-email-olivier.moysan@st.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1560949431-22948-1-git-send-email-olivier.moysan@st.com> References: <1560949431-22948-1-git-send-email-olivier.moysan@st.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.201.23.16] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-19_07:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a comment on DMA configuration for 16 bits record. Signed-off-by: Olivier Moysan --- drivers/iio/adc/stm32-dfsdm-adc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c index d855a605eab6..ee1e0569d0e1 100644 --- a/drivers/iio/adc/stm32-dfsdm-adc.c +++ b/drivers/iio/adc/stm32-dfsdm-adc.c @@ -918,6 +918,11 @@ static void stm32_dfsdm_dma_buffer_done(void *data) static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); + /* + * The DFSDM supports half-word transfers. However, for 16 bits record, + * 4 bytes buswidth is kept, to avoid losing samples LSBs when left + * shift is required. + */ struct dma_slave_config config = { .src_addr = (dma_addr_t)adc->dfsdm->phys_base, .src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES, -- 2.7.4