at91_can.c: Data transmission stops

[Henrik Bork Steffensen <hbs@rosetechnology.dk>]

Hi All,

We use the canopen on an at91sam9263, and experience a can problem.
Sometimes data transmission simply stops. Data reception continues normally.

Reloading the at91_can module seems to be the only action to bring our 
system back on can.
When we experience this problem, the TXF counter in /proc/net/can/stats 
is frozen.

I have followed the thread on a similar issue "pch_can", and I was wondering
if this is the same problem, and if the real problem might be in a 
higher level.

In our case the lockup occurs approximately 1 time in 50 days.
I tried reducing the number of mailboxes used for TX, from 4 to 1.
That seem to increase the frequency of this lockup by a factor 2-5.
These numbers are very uncertain due to the randomness and rarity of 
this bug.

Some numbers to give an impression of our system:
125 kbit bus speed
can bus load <1%
max tx burst 1-6 telegrams, rx is a little bit higher.
240MHz ARM 9 (at91sam9263B)
2.6.32 kernel, with at91_can (and related files) patched with a few 
important fixes.
I would like to move to a recent kernel, but that is not possible right now.


I am considering protecting tx objects as Wolfgang suggests in the 
pch_can thread.

Any ideas?

best regards,
Henrik Bork Steffensen