On Sun, 1 Oct 2023 at 22:40, Linus Walleij <linus.wall...@linaro.org> wrote: > > The max MTU for this ethernet switch is 1536 bytes, not 1510 as it is
The maximum *frame* size accepted is 1536 bytes, not MTU. A difference of 14 bytes. > right now. The available overhead is needed when using the DSA switch with > a cascaded DSA switch, which is something that exist in real products, > in this case the Inteno XG6846. > > Before this patch (on the lan1 DSA port in this case): > dsa_slave_change_mtu: master->max_mtu = 9724, dev->max_mtu = 10218, DSA > overhead = 8 > dsa_slave_change_mtu: master = extsw, dev = lan1 > dsa_slave_change_mtu: master->max_mtu = 1510, dev->max_mtu = 9724, DSA > overhead = 6 > dsa_slave_change_mtu: master = eth0, dev = extsw > dsa_slave_change_mtu new_master_mtu 1514 > mtu_limit 1510 > mdio_mux-0.1:00: nonfatal error -34 setting MTU to 1500 on port 0 > > After this patch the error is gone. Did you test this? As in verified that 1536 bytes long frames are correctly received and sent? > Cc: Álvaro Fernández Rojas <nolt...@gmail.com> > Cc: Jonas Gorski <jonas.gor...@gmail.com> > Signed-off-by: Linus Walleij <linus.wall...@linaro.org> > --- > .../bmips/files/drivers/net/ethernet/broadcom/bcm6368-enetsw.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git > a/target/linux/bmips/files/drivers/net/ethernet/broadcom/bcm6368-enetsw.c > b/target/linux/bmips/files/drivers/net/ethernet/broadcom/bcm6368-enetsw.c > index 321e95dbbb3d..96f4c303a433 100644 > --- a/target/linux/bmips/files/drivers/net/ethernet/broadcom/bcm6368-enetsw.c > +++ b/target/linux/bmips/files/drivers/net/ethernet/broadcom/bcm6368-enetsw.c > @@ -24,6 +24,7 @@ > > /* MTU */ > #define ENETSW_TAG_SIZE (6 + VLAN_HLEN) > +#define ENETSW_MAX_MTU 1536 Again, not MTU. FRAME_LEN. > #define ENETSW_MTU_OVERHEAD (VLAN_ETH_HLEN + VLAN_HLEN + \ > ENETSW_TAG_SIZE) > #define ENETSW_FRAG_SIZE(x) (SKB_DATA_ALIGN(NET_SKB_PAD + x + \ > @@ -1067,7 +1068,7 @@ static int bcm6368_enetsw_probe(struct platform_device > *pdev) > ndev->netdev_ops = &bcm6368_enetsw_ops; > ndev->min_mtu = ETH_ZLEN; > ndev->mtu = ETH_DATA_LEN + ENETSW_TAG_SIZE; > - ndev->max_mtu = ETH_DATA_LEN + ENETSW_TAG_SIZE; > + ndev->max_mtu = ENETSW_MAX_MTU; And here you would need to subtract the ETH_HLEN first, else you will allow 14 bytes too much. Also not sure if the ENETSW_TAG_SIZE should be still added here, as it is stripped on rx and added on tx on the cpu port. Best Regards, Jonas _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel