net: dsa: point out the tail taggers

The Marvell 88E6060 uses tag_trailer.c and the KSZ8795, KSZ9477 and
KSZ9893 switches also use tail tags.

Tell that to the DSA core, since this makes a difference for the flow
dissector. Most switches break the parsing of frame headers, but these
ones don't, so no flow dissector adjustment needs to be done for them.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -90,6 +90,7 @@ struct dsa_device_ops {
 	 * its RX filter.
 	 */
 	bool promisc_on_master;
+	bool tail_tag;
 };
 
 /* This structure defines the control interfaces that are overlayed by the

net/dsa/tag_ksz.c

@@ -237,6 +237,7 @@ static const struct dsa_device_ops ksz9893_netdev_ops = {
 	.xmit	= ksz9893_xmit,
 	.rcv	= ksz9477_rcv,
 	.overhead = KSZ_INGRESS_TAG_LEN,
+	.tail_tag = true,
 };
 
 DSA_TAG_DRIVER(ksz9893_netdev_ops);

net/dsa/tag_trailer.c

@@ -83,6 +83,7 @@ static const struct dsa_device_ops trailer_netdev_ops = {
 	.xmit	= trailer_xmit,
 	.rcv	= trailer_rcv,
 	.overhead = 4,
+	.tail_tag = true,
 };
 
 MODULE_LICENSE("GPL");