Re: Problem using Linux CAN

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hi Tim,

On 24.07.2015 09:53, Tim Hotfilter wrote:

> 1. 500kBaud results in the same problem.
> 2. The problem also occurs with the final configuration (about 5 can nodes). As i mentioned in the first mail, one node has a can-frame watchdog and turns off.
> 3. I had kernel 3.17. before. For testing I upgraded to 3.19

Hm.

> I think the problem is the stopped tx queue.

How did you get this information that the queue is stopped?

The sja1000 queue is stopped in sja1000_start_xmit() and is enabled in 
sja1000_interrupt() again when the tx-ok interrupt (IRQ_TI) occurred.

So when the sja1000 has a stopped queue after some successful time of 
operation the tx-ok interrupt obviously got lost.

As you have two sja1000 cores (from opencores?) in you FPGA: Do you have them 
connected to separate irq lines?

> Is there any chance to implement something like a timeout function, which wakes the queue if the buffer fill level is over a threshold.

We should better try to fix the real issue than implementing workarounds like 
this. There is a timeout recovery for bus-off states (restart-ms option) - but 
your device does not get into bus-off.

Regards,
Oliver