[Bridge] Re: tg3 bridge problems

Neil Horman nhorman at redhat.com
Tue Jan 11 05:12:11 PST 2005

Gergely Madarasz wrote:
> On Tue, Jan 11, 2005 at 07:36:56AM -0500, Neil Horman wrote:
>>Gergely Madarasz wrote:
>>>On Tue, Jan 11, 2005 at 02:36:46PM +1030, Paul Schulz wrote:
>>>>This may be the problem that I have seen (and reported) previously...
>>>>One suggestion.. do a packet dump on an outgoing bridge port, and a 
>>>>dump from a transmitting machine connected to the bridge. Compare the
>>>>MD5 checksums.
>>>Thanks for the idea, but it doesn't seem to help. I've modified the patch
>>>to apply to my chipset revision (and added a debugging printk to make sure
>>>I've hit the right chipset :)), but nothing really changed. I didn't
>>>expect it to either, because this is not a transmit problem, but a
>>>promiscuous receive problem of the driver/card.
>>You know, there is a tg3_dump_state function that if 0-ed out at the 
>>moment, which among other things dumps out the chips RX_MODE.  You could 
>> uncomment that function and tie it to a private ioctl which you could 
>>call from user space.  That way you could compare the RX_MODE values in 
>>a working and a failing environment. If they matched, you could be 
>>reasonably sure it was a hardware issue, otherwise, you would know your 
>>looking for a driver bug.
> It seems they do not match:
> failing: MAC_RX_MODE[00000002]
> working: MAC_RX_MODE[00000102]
> So this would point to a driver bug. To search for that, I added a printk
> at each write to MAC_RX_MODE to see what is being set up. Every call was
> fine, the last always being 0x102. Would it be possible that the buggy
> hardware itself resets this register after a link change or something?
> The following workaround patch made the problem disappear:
> --- tg3.c~      2005-01-11 12:30:21.000000000 +0100
> +++ tg3.c       2005-01-11 12:30:21.000000000 +0100
> @@ -2803,6 +2803,8 @@
> 			sblk->status = SD_STATUS_UPDATED |
> 				(sblk->status & ~SD_STATUS_LINK_CHG);
> 			tg3_setup_phy(tp, 0);
> +			tw32_f(MAC_RX_MODE, tp->rx_mode);
> +			udelay(10);
> 		}
> 	}
> So if I reset the rx_mode after the card has reported a link change,
> promisc works fine. This workaround works on both machines, one having
> rev 4001 cards, the other having rev 2003's.
> Greg

I do believe that tg3 driven chips reset the promisc. bit on chip reset, 
so it may be possible that you have found a driver bug in which the 
appropriate promiscuous state isn't restored after a reset.  Try adding 
a printk to tg3_reset to see if it gets called after you follow your 
non-working procedure, and check to see if the promisc bit in 
MAC_RX_MODE gets lost.  If so, I'd say thats arguably your bug.


  *Neil Horman
  *Software Engineer
  *Red Hat, Inc.
  *nhorman at redhat.com
  *gpg keyid: 1024D / 0x92A74FA1

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