diff options
| author | Angelo Compagnucci <angelo.compagnucci@gmail.com> | 2020-08-19 09:55:25 +0200 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2020-08-31 10:47:53 +0100 |
| commit | 3f1093d83d7164e4705e4232ccf76da54adfda85 (patch) | |
| tree | 24b50934e355163a167d9f01bc8cc72427e95dd2 /drivers/iio | |
| parent | d53bfdf2f0b2ec2d4bcebc4f1a1257d05f78dc51 (diff) | |
iio: adc: mcp3422: fix locking scope
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>
Diffstat (limited to 'drivers/iio')
| -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 5f1706d1c3c0..219adac2384b 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, |