linux-kernel - [PATCH v4 2/4] iio: magnetometer: ak8975: Fix reading for ak099xx sensors

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Message-Id: <20240819-ak09918-v4-2-f0734d14cfb9@mainlining.org>
Date: Mon, 19 Aug 2024 00:29:40 +0200
From: Barnabás Czémán <barnabas.czeman@...nlining.org>
To: Jonathan Cameron <jic23@...nel.org>, 
 Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Jonathan Albrieux <jonathan.albrieux@...il.com>, 
 Gwendal Grignou <gwendal@...omium.org>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, linux@...nlining.org, 
 Barnabás Czémán <barnabas.czeman@...nlining.org>
Subject: [PATCH v4 2/4] iio: magnetometer: ak8975: Fix reading for ak099xx
 sensors

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.

Fixes: 57e73a423b1e ("iio: ak8975: add ak09911 and ak09912 support")
Signed-off-by: Barnabás Czémán <barnabas.czeman@...nlining.org>
---
 drivers/iio/magnetometer/ak8975.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 8eef4d5dd9e2..2fa6721aa66f 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -695,22 +695,8 @@ 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 with zero if the data is ready. */
+	return !data->def->ctrl_regs[ST1_DRDY];
 }
 
 /* Retrieve raw flux value for one of the x, y, or z axis.  */
@@ -737,6 +723,20 @@ 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 on measurment data. */
+	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);

-- 
2.46.0