can: add bittiming check at interface open for CAN FD

Additionally to have the second (data) bitrate available the data bitrate
has to be greater or equal to the arbitration bitrate in CAN FD.
Signed-off-by: NOliver Hartkopp <socketcan@hartkopp.net>
Acked-by: NStephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/dev.c

@@ -642,6 +642,14 @@ int open_candev(struct net_device *dev)
 		return -EINVAL;
 	}
 
+	/* For CAN FD the data bitrate has to be >= the arbitration bitrate */
+	if ((priv->ctrlmode & CAN_CTRLMODE_FD) &&
+	    (!priv->data_bittiming.bitrate ||
+	     (priv->data_bittiming.bitrate < priv->bittiming.bitrate))) {
+		netdev_err(dev, "incorrect/missing data bit-timing\n");
+		return -EINVAL;
+	}
+
 	/* Switch carrier on if device was stopped while in bus-off state */
 	if (!netif_carrier_ok(dev))
 		netif_carrier_on(dev);