[PATCH 1/3] iio: accel: kxsd9: validate input before acquiring runtime PM in write_raw runtime PM in write_raw

[Biren Pandya <birenpandya@gmail.com>]

Currently, kxsd9_write_raw() acquires a runtime PM reference at the very
top of the function, before checking if the requested mask or value are
actually supported. This causes unnecessary hardware wakeups for invalid
inputs.

Refactor write_raw to validate inputs first. Additionally, modernize the
PM runtime call by replacing pm_runtime_get_sync() with
pm_runtime_resume_and_get() and adding the missing error check to
prevent proceeding if power-on fails.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Biren Pandya <birenpandya@gmail.com>
---
 drivers/iio/accel/kxsd9.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/accel/kxsd9.c b/drivers/iio/accel/kxsd9.c
index 7ac885d94d7f4..b3acb20441d86 100644
--- a/drivers/iio/accel/kxsd9.c
+++ b/drivers/iio/accel/kxsd9.c
@@ -139,18 +139,21 @@ static int kxsd9_write_raw(struct iio_dev *indio_dev,
 			   int val2,
 			   long mask)
 {
-	int ret = -EINVAL;
 	struct kxsd9_state *st = iio_priv(indio_dev);
+	int ret;
 
-	pm_runtime_get_sync(st->dev);
+	if (mask != IIO_CHAN_INFO_SCALE)
+		return -EINVAL;
 
-	if (mask == IIO_CHAN_INFO_SCALE) {
-		/* Check no integer component */
-		if (val)
-			ret = -EINVAL;
-		else
-			ret = kxsd9_write_scale(indio_dev, val2);
-	}
+	/* Check no integer component */
+	if (val)
+		return -EINVAL;
+
+	ret = pm_runtime_resume_and_get(st->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = kxsd9_write_scale(indio_dev, val2);
 
 	pm_runtime_put_autosuspend(st->dev);
 
-- 
2.50.1 (Apple Git-155)