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iio: adc: max1027: Prevent single channel accesses during buffer reads

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When hardware buffers are enabled (the cnvst pin being the trigger), one
should not mess with the device state by requesting a single channel
read.

There is already a iio_buffer_enabled() check in *_read_single_value()
to merely prevent this situation but the check is inconsistent since
buffers can be enabled after the if clause anyway. Instead, use the core
mutex by calling iio_device_claim/release_direct_mode().

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20210921115408.66711-11-miquel.raynal@bootlin.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Miquel Raynal
2021-09-21 13:54:02 +02:00
committed by Jonathan Cameron
parent af8b93e27f
commit 59fcc6af89
1 changed files with 7 additions and 4 deletions
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11
drivers/iio/adc/max1027.c
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@ -311,10 +311,9 @@ static int max1027_read_single_value(struct iio_dev *indio_dev,
int ret;
struct max1027_state *st = iio_priv(indio_dev);
if (iio_buffer_enabled(indio_dev)) {
dev_warn(&indio_dev->dev, "trigger mode already enabled");
return -EBUSY;
}
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
/* Configure conversion register with the requested chan */
st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) |
@ -325,6 +324,7 @@ static int max1027_read_single_value(struct iio_dev *indio_dev,
if (ret < 0) {
dev_err(&indio_dev->dev,
"Failed to configure conversion register\n");
iio_device_release_direct_mode(indio_dev);
return ret;
}
@ -337,6 +337,9 @@ static int max1027_read_single_value(struct iio_dev *indio_dev,
/* Read result */
ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ? 4 : 2);
iio_device_release_direct_mode(indio_dev);
if (ret < 0)
return ret;