Messages in this thread | | | Date | Thu, 10 Dec 2020 02:25:02 +0100 | From | Andrew Lunn <> | Subject | Re: [PATCH 01/20] ethernet: ucc_geth: set dev->max_mtu to 1518 |
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On Sat, Dec 05, 2020 at 08:17:24PM +0100, Rasmus Villemoes wrote: > 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") > Cc: Vladimir Oltean <vladimir.oltean@nxp.com> > Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Andrew
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