From: Rasmus Villemoes rasmus.villemoes@prevas.dk
[ Upstream commit 1385ae5c30f238f81bc6528d897c6d7a0816783f ]
All the buffers and registers are already set up appropriately for an MTU slightly above 1500, so we just need to expose this to the networking stack. AFAICT, there's no need to implement .ndo_change_mtu when the receive buffers are always set up to support the max_mtu.
This fixes several warnings during boot on our mpc8309-board with an embedded mv88e6250 switch:
mv88e6085 mdio@e0102120:10: nonfatal error -34 setting MTU 1500 on port 0 ... mv88e6085 mdio@e0102120:10: nonfatal error -34 setting MTU 1500 on port 4 ucc_geth e0102000.ethernet eth1: error -22 setting MTU to 1504 to include DSA overhead
The last line explains what the DSA stack tries to do: achieving an MTU of 1500 on-the-wire requires that the master netdevice connected to the CPU port supports an MTU of 1500+the tagging overhead.
Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports") Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk Reviewed-by: Vladimir Oltean vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/freescale/ucc_geth.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/net/ethernet/freescale/ucc_geth.c +++ b/drivers/net/ethernet/freescale/ucc_geth.c @@ -3889,6 +3889,7 @@ static int ucc_geth_probe(struct platfor INIT_WORK(&ugeth->timeout_work, ucc_geth_timeout_work); netif_napi_add(dev, &ugeth->napi, ucc_geth_poll, 64); dev->mtu = 1500; + dev->max_mtu = 1518;
ugeth->msg_enable = netif_msg_init(debug.msg_enable, UGETH_MSG_DEFAULT); ugeth->phy_interface = phy_interface;