Problems with tg3 on BCM5720

Hi,

I hope this is the right list for this; please let me know if there is
some more appropriate venue for this kind of problem.

We have bought a Dell PowerEdge server recently with Broadcom ethernet
controllers:

01:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5720
Gigabit Ethernet PCIe
01:00.1 Ethernet controller: Broadcom Corporation NetXtreme BCM5720
Gigabit Ethernet PCIe
02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5720
Gigabit Ethernet PCIe
02:00.1 Ethernet controller: Broadcom Corporation NetXtreme BCM5720
Gigabit Ethernet PCIe

Using the tg3 driver as provided by the 3.4.9 kernel (it's a distro
kernel, but I verified that there are no relevant patches on top of
the vanilla 3.4.9), networking works fine on a small VLAN. However,
we've run into trouble connecting one of the interfaces to switch run
by our data center vendor (the switch side works fine when connecting
with a laptop). The driver keeps erroring out with "transmit timed
out, resetting" (full syslog output is at [1]). This also keeps
happening when I use the latest tg3.{c,h} from torvalds/linux-2.6
(though I've had to revert a few things to make it compile inside the
3.4.9 kernel).

I've also run some tests with ethtool:

djc@jansky ~ $ sudo ethtool --test eth0
The test result is FAIL
The test extra info:
nvram test        (online)       0
link test         (online)       1
register test     (offline)      0
memory test       (offline)      0
mac loopback test (offline)      7
phy loopback test (offline)      7
ext loopback test (offline)      0
interrupt test    (offline)      1

While I'd be happy to do more digging, at this point I'm out of ideas
on how to go about that.

Again, sorry if this is off-topic for this list, any help would be appreciated.

Cheers,

Dirkjan

[1] http://dirkjan.ochtman.nl/files/tg3-fail.txt