can: c_can: end pending transmission on network stop (ifdown)

commit 7ffd7b4e upstream.

Put controller into init mode in network stop to end pending transmissions. The
issue is observed in cases when transmitted frame is not acked.
Signed-off-by: Viktor Babrian <babrian.viktor@renyi.mta.hu>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[ kamal: backport to 3.13-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/net/can/c_can/c_can.c

@@ -694,6 +694,9 @@ static void c_can_stop(struct net_device *dev)
 	/* disable all interrupts */
 	c_can_enable_all_interrupts(priv, DISABLE_ALL_INTERRUPTS);
 
+	/* put ctrl to init on stop to end ongoing transmission */
+	priv->write_reg(priv, C_CAN_CTRL_REG, CONTROL_INIT);
+
 	/* set the state as STOPPED */
 	priv->can.state = CAN_STATE_STOPPED;
 }