[PATCH 5.7 087/120] net: ethernet: mtk_eth_soc: fix MTU warnings

From: Greg Kroah-Hartman
Date: Mon Aug 03 2020 - 08:48:25 EST

From: Landen Chao <landen.chao@xxxxxxxxxxxx>

[ Upstream commit 555a893303872e044fb86f0a5834ce78d41ad2e2 ]

in recent kernel versions there are warnings about incorrect MTU size
like these:

eth0: mtu greater than device maximum
mtk_soc_eth 1b100000.ethernet eth0: error -22 setting MTU to include DSA overhead

Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports")
Fixes: 72579e14a1d3 ("net: dsa: don't fail to probe if we couldn't set the MTU")
Fixes: 7a4c53bee332 ("net: report invalid mtu value via netlink extack")
Signed-off-by: Landen Chao <landen.chao@xxxxxxxxxxxx>
Signed-off-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
Reviewed-by: Andrew Lunn <andrew@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 09047109d0daa..b743d8b56c848 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -2882,6 +2882,8 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
eth->netdev[id]->irq = eth->irq[0];
eth->netdev[id]->dev.of_node = np;

+ eth->netdev[id]->max_mtu = MTK_MAX_RX_LENGTH - MTK_RX_ETH_HLEN;
return 0;