linux-kernel - [PATCH AUTOSEL for 4.9 22/50] iio: pressure: ms5611: claim direct mode during oversampling changes

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Date:   Wed, 25 Oct 2017 01:55:57 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Alison Schofield <amsfield22@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Subject: [PATCH AUTOSEL for 4.9 22/50] iio: pressure: ms5611: claim direct
 mode during oversampling changes

From: Alison Schofield <amsfield22@...il.com>

[ Upstream commit 3bc1abcddb24f55b9c251e03caa4f9bd22ff748b ]

Driver was checking for direct mode before changing oversampling
ratios, but was not locking it.  Use the claim/release helper
functions to guarantee the device stays in direct mode while the
oversampling ratios are being updated.  Continue to use the drivers
private state lock to protect against conflicting direct mode access
of the state data.

Signed-off-by: Alison Schofield <amsfield22@...il.com>
Signed-off-by: Jonathan Cameron <jic23@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 drivers/iio/pressure/ms5611_core.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c
index a74ed1f0c880..8cc7156b5ace 100644
--- a/drivers/iio/pressure/ms5611_core.c
+++ b/drivers/iio/pressure/ms5611_core.c
@@ -308,6 +308,7 @@ static int ms5611_write_raw(struct iio_dev *indio_dev,
 {
 	struct ms5611_state *st = iio_priv(indio_dev);
 	const struct ms5611_osr *osr = NULL;
+	int ret;
 
 	if (mask != IIO_CHAN_INFO_OVERSAMPLING_RATIO)
 		return -EINVAL;
@@ -321,12 +322,11 @@ static int ms5611_write_raw(struct iio_dev *indio_dev,
 	if (!osr)
 		return -EINVAL;
 
-	mutex_lock(&st->lock);
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
 
-	if (iio_buffer_enabled(indio_dev)) {
-		mutex_unlock(&st->lock);
-		return -EBUSY;
-	}
+	mutex_lock(&st->lock);
 
 	if (chan->type == IIO_TEMP)
 		st->temp_osr = osr;
@@ -334,6 +334,8 @@ static int ms5611_write_raw(struct iio_dev *indio_dev,
 		st->pressure_osr = osr;
 
 	mutex_unlock(&st->lock);
+	iio_device_release_direct_mode(indio_dev);
+
 	return 0;
 }
 
-- 
2.11.0