[PATCH v2 net-next 6/8] net: dsa: sja1105: increase MTU to account for VLAN header on DSA ports

Vladimir Oltean
2021-08-04T13:17:33Z

Since all packets are transmitted as VLAN-tagged over a DSA link (this
VLAN tag represents the tag_8021q header), we need to increase the MTU
of these interfaces to account for the possibility that we are already
transporting a user-visible VLAN header.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
drivers/net/dsa/sja1105/sja1105_main.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index d1d4d956cae8..fffcaef6b148 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -982,7 +982,7 @@ static int sja1105_init_l2_policing(struct sja1105_private *priv)
for (port = 0; port < ds->num_ports; port++) {
int mtu = VLAN_ETH_FRAME_LEN + ETH_FCS_LEN;

- if (dsa_is_cpu_port(priv->ds, port))
+ if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port))
mtu += VLAN_HLEN;

policing[port].smax = 65535; /* Burst size in bytes */
@@ -2664,7 +2664,7 @@ static int sja1105_change_mtu(struct dsa_switch *ds, int port, int new_mtu)

new_mtu += VLAN_ETH_HLEN + ETH_FCS_LEN;

- if (dsa_is_cpu_port(ds, port))
+ if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port))
new_mtu += VLAN_HLEN;

policing = priv->static_config.tables[BLK_IDX_L2_POLICING].entries;
--
2.25.1