can: flexcan: handle state passive -> warning transition

Once the CAN-bus is open and a packet is sent, the controller switches
into the PASSIVE state. Once the BUS is closed again it goes the back
err-warning. The TX error counter goes 0 -> 0x80 -> 0x7f.
This patch makes sure that the user learns about this state chang
(CAN_STATE_ERROR_WARNING => CAN_STATE_ERROR_PASSIVE)

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Matthias Klein <matthias.klein@optimeas.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/flexcan.c

@@ -549,6 +549,13 @@ static void do_state(struct net_device *dev,
 
 	/* process state changes depending on the new state */
 	switch (new_state) {
+	case CAN_STATE_ERROR_WARNING:
+		netdev_dbg(dev, "Error Warning\n");
+		cf->can_id |= CAN_ERR_CRTL;
+		cf->data[1] = (bec.txerr > bec.rxerr) ?
+			CAN_ERR_CRTL_TX_WARNING :
+			CAN_ERR_CRTL_RX_WARNING;
+		break;
 	case CAN_STATE_ERROR_ACTIVE:
 		netdev_dbg(dev, "Error Active\n");
 		cf->can_id |= CAN_ERR_PROT;