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Commit 5571056a authored by Angelo Compagnucci's avatar Angelo Compagnucci Committed by Greg Kroah-Hartman
Browse files

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: 07914c84 ("iio: adc: Add driver for Microchip MCP3422/3/4 high resolution ADC")
Signed-off-by: default avatarAngelo 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: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f7db0231

drivers/iio/adc/mcp3422.c

+7 −5
Original line number Diff line number Diff line
@@ -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,