[PATCH v3 2/4] iio: health: max30100: do not use internal iio_dev lock

["Nuno Sá" <nuno.sa@analog.com>]

The pattern used in this device does not quite fit in the
iio_device_claim_direct_mode() typical usage. In this case,
iio_buffer_enabled() was being used not to prevent the raw access but to
allow it. Hence, let's make use of the new
iio_device_claim_buffer_mode() API to make sure we stay in buffered mode
during the complete read.

Note that we are shadowing the error code returned by
iio_device_claim_buffer_mode() so that we keep the original one
(-EAGAIN). The reason is that some userspace stack might already be
relying on this particular code so that we are not taking chances and
leave it alone.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
---
 drivers/iio/health/max30100.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c
index 2cca5e0519f8..6ac49901c9da 100644
--- a/drivers/iio/health/max30100.c
+++ b/drivers/iio/health/max30100.c
@@ -387,18 +387,15 @@ static int max30100_read_raw(struct iio_dev *indio_dev,
 		 * Temperature reading can only be acquired while engine
 		 * is running
 		 */
-		mutex_lock(&indio_dev->mlock);
-
-		if (!iio_buffer_enabled(indio_dev))
+		if (iio_device_claim_buffer_mode(indio_dev)) {
 			ret = -EAGAIN;
-		else {
+		} else {
 			ret = max30100_get_temp(data, val);
 			if (!ret)
 				ret = IIO_VAL_INT;
 
+			iio_device_release_buffer_mode(indio_dev);
 		}
-
-		mutex_unlock(&indio_dev->mlock);
 		break;
 	case IIO_CHAN_INFO_SCALE:
 		*val = 1;  /* 0.0625 */
-- 
2.38.0


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