From 1385ae5c30f238f81bc6528d897c6d7a0816783f Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 18 Dec 2020 11:55:36 +0100 Subject: [PATCH] ethernet: ucc_geth: set dev->max_mtu to 1518 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 Signed-off-by: Rasmus Villemoes Reviewed-by: Vladimir Oltean Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/freescale/ucc_geth.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c index ba8869c3d891c0..d6dbae48071615 100644 --- 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 platform_device* ofdev) 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;