linux-kernel - [PATCH 1/2] iio: humidity: hdc100x: move lock on config updates to single function

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Date:	Sun, 10 Jul 2016 14:30:01 -0700
From:	Alison Schofield <amsfield22@...il.com>
To:	jic23@...nel.org
Cc:	mranostay@...il.com, knaack.h@....de, lars@...afoo.de,
	pmeerw@...erw.net, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] iio: humidity: hdc100x: move lock on config updates to
 single function

Move the config register locking to the config update function.  This
continues to protect updates to heater and integration times. It puts
the lock in one place, right where it needs to occur.

Add the checkpatch required comment on this lock declaration.

Signed-off-by: Alison Schofield <amsfield22@...il.com>
Cc: Daniel Baluta <daniel.baluta@...il.com>
---
 drivers/iio/humidity/hdc100x.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c
index a03832a..ad5a12a 100644
--- a/drivers/iio/humidity/hdc100x.c
+++ b/drivers/iio/humidity/hdc100x.c
@@ -31,7 +31,7 @@
 
 struct hdc100x_data {
 	struct i2c_client *client;
-	struct mutex lock;
+	struct mutex lock;  /* protect config updates & raw measurements */
 	u16 config;
 
 	/* integration time of the sensor */
@@ -108,10 +108,12 @@ static int hdc100x_update_config(struct hdc100x_data *data, int mask, int val)
 	int tmp = (~mask & data->config) | val;
 	int ret;
 
+	mutex_lock(&data->lock);
 	ret = i2c_smbus_write_word_swapped(data->client,
 						HDC100X_REG_CONFIG, tmp);
 	if (!ret)
 		data->config = tmp;
+	mutex_unlock(&data->lock);
 
 	return ret;
 }
@@ -234,26 +236,20 @@ static int hdc100x_write_raw(struct iio_dev *indio_dev,
 			     int val, int val2, long mask)
 {
 	struct hdc100x_data *data = iio_priv(indio_dev);
-	int ret = -EINVAL;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_INT_TIME:
 		if (val != 0)
 			return -EINVAL;
 
-		mutex_lock(&data->lock);
-		ret = hdc100x_set_it_time(data, chan->address, val2);
-		mutex_unlock(&data->lock);
-		return ret;
+		return hdc100x_set_it_time(data, chan->address, val2);
+
 	case IIO_CHAN_INFO_RAW:
 		if (chan->type != IIO_CURRENT || val2 != 0)
 			return -EINVAL;
 
-		mutex_lock(&data->lock);
-		ret = hdc100x_update_config(data, HDC100X_REG_CONFIG_HEATER_EN,
+		return hdc100x_update_config(data, HDC100X_REG_CONFIG_HEATER_EN,
 					val ? HDC100X_REG_CONFIG_HEATER_EN : 0);
-		mutex_unlock(&data->lock);
-		return ret;
 	default:
 		return -EINVAL;
 	}
-- 
2.1.4