Broadcom TG3 network drops, cannot recover without reboot

[Justin Catterall <justin@masonsmusic.co.uk>]

At irregular times, and apparently for no reason at all, networking
drops and cannot be restarted without reboot on a fresh install of
Jessie. The NIC is a Broadcom NetXtreme BCM5720.

ifconfig thinks networking is still up because I can:
	ifconfig eth0 down

I find this when I try 'ifconfig eth0 up':
tg3_abort_hw timed out TX_MODE_ENABLE will not clear MAC_TX_MODE=ffffffff

If I:
    rmmod tg3; insmod tg3
the problem does not resolve. It seems the card needs a hard reset.

Searching the web there are various issues with the TG3, and most
are resolved by installing firmware-linux-nonfree. I have this
module installed but I can re-create the problem by running
/etc/init.d/networking restart. The networking stops working completely, I can't ping the machine nor can I ping from the machine.

Any suggestions on where to look for a solution?


-- 
Justin C, by the sea.