Re: c_can: wrong frame order reception

[wouter van herpen <wouter.van.herpen@prodrive-technologies.com>]

> you can try to use the SMP-affinity to pin the innterrupt to a specific CPU:
> 
> 	https://www.kernel.org/doc/Documentation/IRQ-affinity.txt
> 
> But we're currently also checking the usability of receive packet steering 
> (RPS) on SMP systems. Please check
> 
> 	http://marc.info/?l=linux-can&m=144251788500555&w=2
> 
> whether just using
> 
> 	echo f > /sys/class/net/can0/queues/rx-0/rps_cpus
> 
> helps in you case or whether you need to set the skb hash which is suggested 
> there too.
> 
> 

Hi Oliver,

I have tried SMP affinity, in combination with adjusting
/sys/class/net/can0/queues/rx-0/rps_cpus. These changes did not solve the
out of order reception.
Also adding skb_set_hash(skb, dev->ifindex, PKT_HASH_TYPE_L2); did not make
a difference.

Do you have any other suggestions?

I have also done some testing with the pch_can driver. I noticed there the
out of order receptions are less frequent. Using the pch_can driver, OOO
reception only occurs if we stress the CPU over e.g. UART.
Using c_can driver, the OOO replies occur more often.