lwip-users
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [lwip-users] Transmission stall after ARP broadcast


From: Stephan Hilchenbach
Subject: Re: [lwip-users] Transmission stall after ARP broadcast
Date: Fri, 16 Feb 2018 08:35:09 +0000

>> So is there *any* communication from the device after this? Maybe on the 2nd 
>> port?
After this incident receiving goes on. This means, the DMA handles incoming 
packets but does not accept any outgoing packets. The second port is not 
connected. The phy is not active.

>> I don't know how the software on that processor is adapted to lwIP but 
>> strictly speaking, this is not a switch but 2 MACs connected via the PRUs. 
>> They might have bugs, too :-)
The PRU's are not used. It's the CPSW_3G switch. What I found is, that I can 
avoid (so far) this problem, when I reduce the MDIO communication to the second 
port's phy to a minimum. Initially the driver tried to auto negotiate with the 
phy, even when there was no link. I changed this now and wait for a link first. 
I checked all code lines and in these procedures the LwIP is not involved. At 
this point I get confused. Somehow the LwIP is influenced by the phy 
communication and the state of the switch. Because there is no delay between 
the last sent data packet an the unexpected ARP broadcast, which is then the 
last transmission of the DMA. Probably the memory is overwritten somewhere. 
This problem also disappears as soon as the second port is connected too.

>> Have you tried to debug what's going on in the processor after it stops?
Yes I did. The integrated DMA (CPDMA) stops sending without showing any error. 
The DMA state is idle, but not responding to new descriptors. I created a 
thread in the Ti forum:
https://e2e.ti.com/support/arm/sitara_arm/f/791/p/663155/2442288
The fact that this behavior is unknown indicates that my driver is doing 
something stupid.

Best Regards,
Stephan

-----Urspr√ľngliche Nachricht-----
Von: lwip-users [mailto:address@hidden Im Auftrag von Simon Goldschmidt
Gesendet: Freitag, 16. Februar 2018 08:55
An: address@hidden
Betreff: Re: [lwip-users] Transmission stall after ARP broadcast

Stephan Hilchenbach wrote:
>>> 1.4.1 is rather old. There have been numerous bugs fixed since then.
> Yes I know. I would prefer to update, but I can't make this decision on my 
> own.

Then talk to whoever is in a position to decide. From the pcap, I can't tell 
what's wrong.
It does not seem like an lwIP issue, but maybe it is.

If I were you, I'd first check with a newer version of lwIP before digging into 
the hardware drivers. Especially with that processor ;-)

>>> No. In general, lwIP has *nothing* to do with your hardware. The netif 
>>> driver is responsible for that.
> I expected this answer, but was not sure about this. It was very curious that 
> the port always stops with transmission of an ARP broadcast.
> The device is configured as a switch with 2 ports. One port is connected, the 
> other one is not. A task cyclically checks the second port for phy activity.

So is there *any* communication from the device after this? Maybe on the 2nd 
port?
I don't know how the software on that processor is adapted to lwIP but strictly 
speaking, this is not a switch but 2 MACs connected via the PRUs. They might 
have bugs, too :-)

Have you tried to debug what's going on in the processor after it stops?

Simon

_______________________________________________
lwip-users mailing list
address@hidden
https://lists.nongnu.org/mailman/listinfo/lwip-users



-----
E-Mail ist virenfrei.
Von AVG uberpruft - www.avg.de
Version: 2013.0.3556 / Virendatenbank: 4793/15405 - Ausgabedatum: 15.02.2018 








reply via email to

[Prev in Thread] Current Thread [Next in Thread]