gianfar.c null pointer deref in gfar_start_xmit().

While using the v3.0 kernel on a Freescale P1010RDB with 3 minor patches
(None which affect gianfar.c), I get a NULL pointer deref at:

static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
...
	regs = tx_queue->grp->regs;

I put a BUG_ON(tx_queue->grp) just before this line and it did trip.
I have not looked at this any more than that.

Any suggestions would be welcome.   To reproduce, all I need to do is
a few sequences of pings.

Thanks,
Robin