[PATCH 3.10 17/34] iio: inv_mpu6050: Clear timestamps fifo while resetting hardware fifo

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Viorel Suman <viorel.suman@gmail.com>

commit 4dac0a8eefd55bb1f157d1a5a084531334a2d74c upstream.

A hardware fifo reset always imply an invalidation of the
existing timestamps, so we'll clear timestamps fifo on
successfull hardware fifo reset.

Signed-off-by: Viorel Suman <viorel.suman@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c |   25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
@@ -25,6 +25,16 @@
 #include <linux/poll.h>
 #include "inv_mpu_iio.h"
 
+static void inv_clear_kfifo(struct inv_mpu6050_state *st)
+{
+	unsigned long flags;
+
+	/* take the spin lock sem to avoid interrupt kick in */
+	spin_lock_irqsave(&st->time_stamp_lock, flags);
+	kfifo_reset(&st->timestamps);
+	spin_unlock_irqrestore(&st->time_stamp_lock, flags);
+}
+
 int inv_reset_fifo(struct iio_dev *indio_dev)
 {
 	int result;
@@ -51,6 +61,10 @@ int inv_reset_fifo(struct iio_dev *indio
 					INV_MPU6050_BIT_FIFO_RST);
 	if (result)
 		goto reset_fifo_fail;
+
+	/* clear timestamps fifo */
+	inv_clear_kfifo(st);
+
 	/* enable interrupt */
 	if (st->chip_config.accl_fifo_enable ||
 	    st->chip_config.gyro_fifo_enable) {
@@ -84,16 +98,6 @@ reset_fifo_fail:
 	return result;
 }
 
-static void inv_clear_kfifo(struct inv_mpu6050_state *st)
-{
-	unsigned long flags;
-
-	/* take the spin lock sem to avoid interrupt kick in */
-	spin_lock_irqsave(&st->time_stamp_lock, flags);
-	kfifo_reset(&st->timestamps);
-	spin_unlock_irqrestore(&st->time_stamp_lock, flags);
-}
-
 /**
  * inv_mpu6050_irq_handler() - Cache a timestamp at each data ready interrupt.
  */
@@ -187,7 +191,6 @@ end_session:
 flush_fifo:
 	/* Flush HW and SW FIFOs. */
 	inv_reset_fifo(indio_dev);
-	inv_clear_kfifo(st);
 	mutex_unlock(&indio_dev->mlock);
 	iio_trigger_notify_done(indio_dev->trig);