On Thu, Jul 09, 2020 at 03:41:15PM +0200, Andrew Lunn wrote:
> On Thu, Jul 09, 2020 at 07:57:42AM +0200, Frank Wunderlich wrote:
> > From: RenĂ© van Dorst <[email protected]>
> > 
> > in recent Kernel-Versions there are warnings about incorrect MTU-Size
> > like these:
> > 
> > mt7530 mdio-bus:00: nonfatal error -95 setting MTU on port x
> > 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: RenĂ© van Dorst <[email protected]>
> > Signed-off-by: Frank Wunderlich <[email protected]>
> > ---
> > changes in v2:
> >   Fixes: tag show 12-chars of sha1 and moved above other tags
> > ---
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c 
> > b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > index 85735d32ecb0..00e3d70f7d07 100644
> > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > @@ -2891,6 +2891,10 @@ 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]->mtu = 1536;
> 
> Hi Frank
> 
> Don't change to MTU from the default. Anybody using this interface for
> non-DSA traffic expects the default MTU. DSA will change it as needed.
> 
> > +   eth->netdev[id]->min_mtu = ETH_MIN_MTU;
> 
> No need to set the minimum. ether_setup() will initialize it.
> 
> > +   eth->netdev[id]->max_mtu = 1536;
> 
> I assume this is enough to make the DSA warning go away, but it is the
> true max? I have a similar patch for the FEC driver which i should
> post sometime. Reviewing the FEC code and after some testing, i found
> the real max was 2K - 64.

Are there any plans to solve these warnings for Marvell 88e6xxx DSA ports?

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