Commit 59fcc6af authored by Miquel Raynal's avatar Miquel Raynal Committed by Jonathan Cameron
Browse files

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



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: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20210921115408.66711-11-miquel.raynal@bootlin.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent af8b93e2

drivers/iio/adc/max1027.c

+7 −4
Original line number Diff line number Diff line
@@ -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;