| Message ID | 20180704183324.10605-5-linus.walleij@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [net-next,1/5,v2] net: gemini: Look up L3 maxlen from table | expand |
On Wed, Jul 04, 2018 at 08:33:24PM +0200, Linus Walleij wrote: > The hardware supposedly handles frames up to 10236 bytes and > implements .ndo_change_mtu() so accept 10236 minus the ethernet > header for a VLAN tagged frame on the netdevices. Use > ETH_MIN_MTU as minimum MTU. > > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Hi Linus Did you try with an MTU of 68? Maybe the vendor picked 256 because of a hardware limit? Otherwise the change looks good. Andrew
On Wed, Jul 4, 2018 at 10:35 PM Andrew Lunn <andrew@lunn.ch> wrote: > > On Wed, Jul 04, 2018 at 08:33:24PM +0200, Linus Walleij wrote: > > The hardware supposedly handles frames up to 10236 bytes and > > implements .ndo_change_mtu() so accept 10236 minus the ethernet > > header for a VLAN tagged frame on the netdevices. Use > > ETH_MIN_MTU as minimum MTU. > > > > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > > Hi Linus > > Did you try with an MTU of 68? Maybe the vendor picked 256 because of > a hardware limit? Yeah works fine: ping -s 68 169.254.1.2 PING 169.254.1.2 (169.254.1.2) 68(96) bytes of data. 76 bytes from 169.254.1.2: icmp_seq=1 ttl=64 time=0.359 ms 76 bytes from 169.254.1.2: icmp_seq=2 ttl=64 time=0.346 ms 76 bytes from 169.254.1.2: icmp_seq=3 ttl=64 time=0.351 ms This also works fine: ping -s 9000 169.254.1.2 PING 169.254.1.2 (169.254.1.2) 9000(9028) bytes of data. 9008 bytes from 169.254.1.2: icmp_seq=1 ttl=64 time=1.45 ms 9008 bytes from 169.254.1.2: icmp_seq=2 ttl=64 time=1.68 ms 9008 bytes from 169.254.1.2: icmp_seq=3 ttl=64 time=1.55 ms I'll send new patches with all suggested changes soon :) Thanks a lot for your help! Yours, Linus Walleij
diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c index 4e341570047f..af38f9869734 100644 --- a/drivers/net/ethernet/cortina/gemini.c +++ b/drivers/net/ethernet/cortina/gemini.c @@ -2476,6 +2476,11 @@ static int gemini_ethernet_port_probe(struct platform_device *pdev) netdev->hw_features = GMAC_OFFLOAD_FEATURES; netdev->features |= GMAC_OFFLOAD_FEATURES | NETIF_F_GRO; + /* We can handle jumbo frames up to 10236 bytes so, let's accept + * payloads of 10236 bytes minus VLAN and ethernet header + */ + netdev->min_mtu = ETH_MIN_MTU; + netdev->max_mtu = 10236 - VLAN_ETH_HLEN; port->freeq_refill = 0; netif_napi_add(netdev, &port->napi, gmac_napi_poll,
The hardware supposedly handles frames up to 10236 bytes and implements .ndo_change_mtu() so accept 10236 minus the ethernet header for a VLAN tagged frame on the netdevices. Use ETH_MIN_MTU as minimum MTU. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- ChangeLog v1->v2: - Change the min MTU from 256 (vendor code) to ETH_MIN_MTU which makes more sense. --- drivers/net/ethernet/cortina/gemini.c | 5 +++++ 1 file changed, 5 insertions(+) -- 2.17.1