[PATCH v9 03/10] iio: accel: mma8452: Fix runtime PM bugs in mma8452_read()

[Esben Haabendal]

When runtime PM support was added [1], the implementation in mma8452_read()
was done incorrectly, as it calls mma8452_drdy() before ensuring runtime pm
has set the device active, so it can cause read from STATUS register while
device is suspended/off. At the same time, the return value from
i2c_smbus_read_i2c_block_data() was discarded, and the function would
return the value returned from pm_runtime_put_autosuspend() instead.

When the latter bug described above was fixed [2], another bug was
introduced, as mma8452_read() would now leak the runtime PM reference
counter when i2c_smbus_read_i2c_block_data() failed.

This commit corrects this mess.

[1] commit 96c0cb2bbfe0 ("iio: mma8452: add support for runtime power management")
[2] commit 5bdff291d20c ("iio: accel: mma8452: handle I2C read error(s) in mma8452_read()")

Fixes: 96c0cb2bbfe0 ("iio: mma8452: add support for runtime power management")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Esben Haabendal <esben@xxxxxxxxxx>
---
 drivers/iio/accel/mma8452.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index a937cbd84f30..a77c4b88b61d 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -242,21 +242,25 @@ static int mma8452_set_runtime_pm_state(struct i2c_client *client, bool on)
 
 static int mma8452_read(struct mma8452_data *data, __be16 buf[3])
 {
-	int ret = mma8452_drdy(data);
-
-	if (ret < 0)
-		return ret;
+	int ret;
 
 	ret = mma8452_set_runtime_pm_state(data->client, true);
 	if (ret)
 		return ret;
 
+	ret = mma8452_drdy(data);
+	if (ret < 0)
+		goto out_runtime_put;
+
 	ret = i2c_smbus_read_i2c_block_data(data->client, MMA8452_OUT_X,
 					    3 * sizeof(__be16), (u8 *)buf);
 	if (ret < 0)
-		return ret;
+		goto out_runtime_put;
+
+	return mma8452_set_runtime_pm_state(data->client, false);
 
-	ret = mma8452_set_runtime_pm_state(data->client, false);
+out_runtime_put:
+	mma8452_set_runtime_pm_state(data->client, false);
 
 	return ret;
 }

-- 
2.55.0