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authorAngelo Compagnucci <angelo.compagnucci@gmail.com>2020-08-19 09:55:25 +0200
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2020-08-31 10:47:53 +0100
commit3f1093d83d7164e4705e4232ccf76da54adfda85 (patch)
tree24b50934e355163a167d9f01bc8cc72427e95dd2 /drivers/iio/adc/mcp3422.c
parentd53bfdf2f0b2ec2d4bcebc4f1a1257d05f78dc51 (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/adc/mcp3422.c')
-rw-r--r--drivers/iio/adc/mcp3422.c12
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,