[PATCH 3.16.y-ckt 107/144] iio: inv_mpu6050: Clear timestamps fifo while resetting hardware fifo

[Luis Henriques <luis.henriques@canonical.com>]

3.16.7-ckt10 -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: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
index 0cd306a72a6e..ba27e277511f 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
@@ -24,6 +24,16 @@
 #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;
@@ -50,6 +60,10 @@ int inv_reset_fifo(struct iio_dev *indio_dev)
 					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) {
@@ -83,16 +97,6 @@ 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.
  */
@@ -184,7 +188,6 @@ 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);