[PATCH v3 2/4] iio: magnetometer: ak8975: Fix reading for ak099xx sensors

["Barnabás Czémán" <barnabas.czeman@mainlining.org>]

Move ST2 reading with overflow handling after measurement data
reading.
ST2 register read have to be read after read measurment data,
because it means end of the reading and realease the lock on the data.
Remove ST2 read skip on interrupt based waiting because ST2 required to
be read out at and of the axis read.

Signed-off-by: Barnabás Czémán <barnabas.czeman@mainlining.org>
---
 drivers/iio/magnetometer/ak8975.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 6357666edd34..f8355170f529 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -692,22 +692,7 @@ static int ak8975_start_read_axis(struct ak8975_data *data,
 	if (ret < 0)
 		return ret;
 
-	/* This will be executed only for non-interrupt based waiting case */
-	if (ret & data->def->ctrl_masks[ST1_DRDY]) {
-		ret = i2c_smbus_read_byte_data(client,
-					       data->def->ctrl_regs[ST2]);
-		if (ret < 0) {
-			dev_err(&client->dev, "Error in reading ST2\n");
-			return ret;
-		}
-		if (ret & (data->def->ctrl_masks[ST2_DERR] |
-			   data->def->ctrl_masks[ST2_HOFL])) {
-			dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
-			return -EINVAL;
-		}
-	}
-
-	return 0;
+	return !data->def->ctrl_regs[ST1_DRDY];
 }
 
 /* Retrieve raw flux value for one of the x, y, or z axis.  */
@@ -734,6 +719,20 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
 	if (ret < 0)
 		goto exit;
 
+	/* Read out ST2 for release lock */
+	ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST2]);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in reading ST2\n");
+		goto exit;
+	}
+
+	if (ret & (data->def->ctrl_masks[ST2_DERR] |
+		   data->def->ctrl_masks[ST2_HOFL])) {
+		dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
+		ret = -EINVAL;
+		goto exit;
+	}
+
 	mutex_unlock(&data->lock);
 
 	pm_runtime_mark_last_busy(&data->client->dev);
@@ -746,7 +745,7 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
 
 exit:
 	mutex_unlock(&data->lock);
-	dev_err(&client->dev, "Error in reading axis\n");
+	dev_err(&client->dev, "Error in reading axis %d\n", ret);
 	return ret;
 }
 

-- 
2.46.0