Re: at91sam9260 MACB problem with IP fragmentation

Hallo Nicolas,

On 6-12-2012 14:27, Nicolas Ferre wrote:

Erwin,

On 12/06/2012 12:32 PM, Erwin Rol :

quoted

Hello Nicolas, Havard, all,

I have a very obscure problem with a at91sam9260 board (almost 1 to 1
copy of the Atmel EK).

The MACB seems to stall when I use large (>2 * MTU) UDP datagrams. The
test case is that a udp echo client (PC) sends datagrams with increasing
length to the AT91 until the max length of the UDP datagram is reached.
When there is no IP fragmentation everything is fine, but when the
datagrams are starting to get fragmented the AT91 will not reply
anymore. But as soon as some network traffic happens it goes on again,
and non of the data is lost.

<snip>

quoted

I tried several kernels including the test version from Nicolas that he
posted on LKML in October. They all show the same effect.

[..]

It seems that Matteo has the same behavior: check here:
http://www.spinics.net/lists/netdev/msg218951.html

I tried Matteo's patch and it seems to work. But I don't know if the
patch is really the right solution. I checked again with wireshark and
it really seems the sending that stalls not the receiving. But as soon
as a ethernet frame is received the sending "un-stalls". So maybe the
patch just causes an MACB IRQ at certain moments that causes the sending
to continue?

I am working on the macb driver right now, so I will try to reproduce
and track this issue on my side.

Any luck reproducing it ?


- Erwin