4.15.18 mtk_soc_eth bug

[Adirelle]

For the record, as I don't expect it to be fixed, here is the message I get when the GnuBee starts messing with the ethernet switch, which brings down all communications on that switch until I unplug the GnuBee.

[22345.040000] mtk_soc_eth 1e100000.ethernet eth0: transmit timed out
[22345.050000] mtk_soc_eth 1e100000.ethernet eth0: pdma_cfg:80000067
[22345.060000] mtk_soc_eth 1e100000.ethernet eth0: tx_ring=0, base=1b7a1000, max=256, ctx=1, dtx=0, fdx=0, next=1
[22345.080000] mtk_soc_eth 1e100000.ethernet eth0: rx_ring=0, base=1b6a5000, max=256, calc=255, drx=0

root@exodus:~# uname -a
Linux exodus 4.15.18+ #6 SMP Mon Apr 30 15:08:13 CEST 2018 mips GNU/Linux

[neilbrown]

If you still experience this on recent kernels, please try
ethtool -A ethblack autoneg off; ethtool -A ethblue autoneg off
The hypothesis is that the gnubee sends ethernet "Pause" frames to the switch, and that causes the switch to zone-out.
See also http://jeffq.com/blog/the-ethernet-pause-frame/ and http://lists.infradead.org/pipermail/openwrt-devel/2020-February/021742.html