media: mt9m114: Fix deadlock in get_frame_interval/set_frame_interval

Getting / Setting the frame interval using the V4L2 subdev pad ops
get_frame_interval/set_frame_interval causes a deadlock, as the
subdev state is locked in the [1] but also in the driver itself.

In [2] it's described that the caller is responsible to acquire and
release the lock in this case. Therefore, acquiring the lock in the
driver is wrong.

Remove the lock acquisitions/releases from mt9m114_ifp_get_frame_interval()
and mt9m114_ifp_set_frame_interval().

[1] drivers/media/v4l2-core/v4l2-subdev.c - line 1129
[2] Documentation/driver-api/media/v4l2-subdev.rst

Fixes: 24d756e ("media: i2c: Add driver for onsemi MT9M114 camera sensor")
Cc: stable@vger.kernel.org
Signed-off-by: Mathis Foerst <mathis.foerst@mt.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

Author: Mathis Foerst

drivers/media/i2c/mt9m114.c

@@ -1619,13 +1619,9 @@ static int mt9m114_ifp_get_frame_interval(struct v4l2_subdev *sd,
 	if (interval->which != V4L2_SUBDEV_FORMAT_ACTIVE)
 		return -EINVAL;
 
-	mutex_lock(sensor->ifp.hdl.lock);
-
 	ival->numerator = 1;
 	ival->denominator = sensor->ifp.frame_rate;
 
-	mutex_unlock(sensor->ifp.hdl.lock);
-
 	return 0;
 }
 
@@ -1644,8 +1640,6 @@ static int mt9m114_ifp_set_frame_interval(struct v4l2_subdev *sd,
 	if (interval->which != V4L2_SUBDEV_FORMAT_ACTIVE)
 		return -EINVAL;
 
-	mutex_lock(sensor->ifp.hdl.lock);
-
 	if (ival->numerator != 0 && ival->denominator != 0)
 		sensor->ifp.frame_rate = min_t(unsigned int,
 					       ival->denominator / ival->numerator,
@@ -1659,8 +1653,6 @@ static int mt9m114_ifp_set_frame_interval(struct v4l2_subdev *sd,
 	if (sensor->streaming)
 		ret = mt9m114_set_frame_rate(sensor);
 
-	mutex_unlock(sensor->ifp.hdl.lock);
-
 	return ret;
 }