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| author | Angelo Compagnucci <angelo.compagnucci@gmail.com> | 2020-08-19 09:55:25 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-17 13:47:42 +0200 |
| commit | 5571056a58051d85f22265e6ac62da8e7ac727a7 (patch) | |
| tree | 018c2ba39a6c7c1b0681bc5fdd9ec5f9ae483af7 /drivers/iio/adc | |
| parent | f7db02316a003c67ecf8c02037d21c765b992647 (diff) | |
| download | linux-stable-5571056a58051d85f22265e6ac62da8e7ac727a7.tar.gz linux-stable-5571056a58051d85f22265e6ac62da8e7ac727a7.tar.bz2 linux-stable-5571056a58051d85f22265e6ac62da8e7ac727a7.zip | |
iio: adc: mcp3422: fix locking scope
commit 3f1093d83d7164e4705e4232ccf76da54adfda85 upstream.
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 <angelo.compagnucci@gmail.com>
Link: https://lore.kernel.org/r/20200819075525.1395248-1-angelo.compagnucci@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/iio/adc')
| -rw-r--r-- | drivers/iio/adc/mcp3422.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c index 4d03b1f265d9..8ae4cf135157 100644 --- a/drivers/iio/adc/mcp3422.c +++ b/drivers/iio/adc/mcp3422.c @@ -95,16 +95,12 @@ 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; } @@ -137,6 +133,8 @@ 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; @@ -151,7 +149,11 @@ 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, |