From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932572AbeCMOX7 (ORCPT ); Tue, 13 Mar 2018 10:23:59 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:30155 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752279AbeCMOXz (ORCPT ); Tue, 13 Mar 2018 10:23:55 -0400 From: Fabrice Gasnier To: CC: , , , , , , , , , , Subject: [PATCH 1/2] iio: adc: stm32-dfsdm: fix successive oversampling settings Date: Tue, 13 Mar 2018 15:23:05 +0100 Message-ID: <1520950986-23116-2-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1520950986-23116-1-git-send-email-fabrice.gasnier@st.com> References: <1520950986-23116-1-git-send-email-fabrice.gasnier@st.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG2NODE2.st.com (10.75.127.5) To SFHDAG5NODE3.st.com (10.75.127.15) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-13_07:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When doing successive oversampling settings, it may fail to update filter parameters silently: - First time oversampling is being set, it will be successful, as fl->res is 0 initially. - Next attempts with various oversamp value may return 0 (success), but keep previous filter parameters, due to 'res' never reaches above or equal current 'fl->res'. This is particularly true when setting sampling frequency (that relies on oversamp). Typical failure without error: - run 1st test @16kHz samp freq will succeed - run new test @8kHz will succeed as well - run new test @16kHz (again): sample rate will remain 8kHz without error Fixes: e2e6771c6462 ("IIO: ADC: add STM32 DFSDM sigma delta ADC support") Signed-off-by: Fabrice Gasnier --- drivers/iio/adc/stm32-dfsdm-adc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c index 01422d1..dc911b6 100644 --- a/drivers/iio/adc/stm32-dfsdm-adc.c +++ b/drivers/iio/adc/stm32-dfsdm-adc.c @@ -144,6 +144,7 @@ static int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl, * Leave as soon as if exact resolution if reached. * Otherwise the higher resolution below 32 bits is kept. */ + fl->res = 0; for (fosr = 1; fosr <= DFSDM_MAX_FL_OVERSAMPLING; fosr++) { for (iosr = 1; iosr <= DFSDM_MAX_INT_OVERSAMPLING; iosr++) { if (fast) @@ -193,7 +194,7 @@ static int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl, } } - if (!fl->fosr) + if (!fl->res) return -EINVAL; return 0; -- 1.9.1