nfp: limit the number of TSO segments

Most FWs limit the number of TSO segments a frame can produce
to 64.  This is for fairness and efficiency (of FW datapath)
reasons.  If a frame with larger number of segments is submitted
the FW will drop it.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -3750,6 +3750,8 @@ static void nfp_net_netdev_init(struct nfp_net *nn)
 	netdev->min_mtu = ETH_MIN_MTU;
 	netdev->max_mtu = nn->max_mtu;
 
+	netdev->gso_max_segs = NFP_NET_LSO_MAX_SEGS;
+
 	netif_carrier_off(netdev);
 
 	nfp_net_set_ethtool_ops(netdev);

drivers/net/ethernet/netronome/nfp/nfp_net_ctrl.h

@@ -59,9 +59,12 @@
 #define NFP_NET_RX_OFFSET               32
 
 /**
- * Maximum header size supported for LSO frames
+ * LSO parameters
+ * %NFP_NET_LSO_MAX_HDR_SZ:	Maximum header size supported for LSO frames
+ * %NFP_NET_LSO_MAX_SEGS:	Maximum number of segments LSO frame can produce
  */
 #define NFP_NET_LSO_MAX_HDR_SZ		255
+#define NFP_NET_LSO_MAX_SEGS		64
 
 /**
  * Prepend field types