[PATCH net-next v2 1/2] dsa: lan9303: Add port_max_mtu API

Jerry Ray
2022-12-02T19:18:13Z

Adding in support for reporting the max mtu for a given
port.

Signed-off-by: Jerry Ray <jerry.ray@microchip.com>
---
drivers/net/dsa/lan9303-core.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/net/dsa/lan9303-core.c b/drivers/net/dsa/lan9303-core.c
index 80f07bd20593..baa336bb9d15 100644
--- a/drivers/net/dsa/lan9303-core.c
+++ b/drivers/net/dsa/lan9303-core.c
@@ -1279,6 +1279,25 @@ static int lan9303_port_mdb_del(struct dsa_switch *ds, int port,
return 0;
}

+/* For non-cpu ports, the max frame size is 1518.
+ * The CPU port supports a max frame size of 1522.
+ * There is a JUMBO flag to make the max size 2048, but this driver
+ * presently does not support using it.
+ */
+static int lan9303_port_max_mtu(struct dsa_switch *ds, int port)
+{
+ struct net_device *p = dsa_port_to_master(dsa_to_port(ds, port));
+ struct lan9303 *chip = ds->priv;
+
+ dev_dbg(chip->dev, "%s(%d) entered. NET max_mtu is %d",
+ __func__, port, p->max_mtu);
+
+ if (dsa_port_is_cpu(dsa_to_port(ds, port)))
+ return 1522 - ETH_HLEN - ETH_FCS_LEN;
+ else
+ return 1518 - ETH_HLEN - ETH_FCS_LEN;
+}
+
static const struct dsa_switch_ops lan9303_switch_ops = {
.get_tag_protocol = lan9303_get_tag_protocol,
.setup = lan9303_setup,
@@ -1299,6 +1318,7 @@ static const struct dsa_switch_ops lan9303_switch_ops = {
.port_fdb_dump = lan9303_port_fdb_dump,
.port_mdb_add = lan9303_port_mdb_add,
.port_mdb_del = lan9303_port_mdb_del,
+ .port_max_mtu = lan9303_port_max_mtu,
};

static int lan9303_register_switch(struct lan9303 *chip)
--
2.17.1