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[185.100.178.123]) by smtp.gmail.com with ESMTPSA id z17sm17276199edi.19.2020.08.19.00.53.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2020 00:53:48 -0700 (PDT) From: Angelo Compagnucci X-Google-Original-From: Angelo Compagnucci To: linux-iio@vger.kernel.org Cc: Angelo Compagnucci Subject: [PATCH v2] iio: adc: mcp3422: fix locking scope Date: Wed, 19 Aug 2020 09:53:45 +0200 Message-Id: <20200819075345.1392772-1-angelo@amarulasolutions.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Angelo Compagnucci Locking should be held for the entire reading sequence involving setting the channel, waiting for the channel switch and reading from the channel. If not, reading from a channel can result mixing with the reading from another channel. Fixes: 07914c84ba30 ("iio: adc: Add driver for Microchip MCP3422/3/4 high resolution ADC") Signed-off-by: Angelo Compagnucci --- drivers/iio/adc/mcp3422.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c index d86c0b5d80a3..02a60fb164cd 100644 --- a/drivers/iio/adc/mcp3422.c +++ b/drivers/iio/adc/mcp3422.c @@ -96,16 +96,12 @@ static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig) { int ret; - mutex_lock(&adc->lock); - ret = i2c_master_send(adc->i2c, &newconfig, 1); if (ret > 0) { adc->config = newconfig; ret = 0; } - mutex_unlock(&adc->lock); - return ret; } @@ -138,6 +134,8 @@ static int mcp3422_read_channel(struct mcp3422 *adc, u8 config; u8 req_channel = channel->channel; + mutex_lock(&adc->lock); + if (req_channel != MCP3422_CHANNEL(adc->config)) { config = adc->config; config &= ~MCP3422_CHANNEL_MASK; @@ -150,7 +148,11 @@ static int mcp3422_read_channel(struct mcp3422 *adc, msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]); } - return mcp3422_read(adc, value, &config); + ret = mcp3422_read(adc, value, &config); + + mutex_unlock(&adc->lock); + + return ret; } static int mcp3422_read_raw(struct iio_dev *iio,