Re: [Linuxptp-users] received SYNC without timestamp

[Martin P. <pec...@fe...>]

Hi Jake and others.

I'm sorry for the slow response time, but it's Christmas time and I have 
vacation. This also means I won't physically get to the computer until 
January, but it is still running with the faulty Gbit card (igb driver), 
so I can examine it remotely. Answers follow.

Dne 18. 12. 21 v 13:13 lin...@li... 
napsal(a):

> Ok. So its based on the 4.9 kernel?
Yes.
> The only other thing I might suggest is using ftrace to check whether
> igb_ptp_rx_rgtstamp and related functions are actually being called.
>
> This function is called in igb_process_skb_fields when a receive packet
> is detected as having a timestamp captured in the register.

Fortunately, the kernel has ftrace already enabled, so I did the test 
with the PTP client running. What's interesting is that ftrace doesn't 
report any calls of igb_process_skb_fields. It does also report no 
usages of igb_ptp_rx_tgtstamp. However, I saw this in the log:

      kworker/4:0-9357  [004] ...1 471985.266393: igb_ptp_rx_hang 
<-igb_watchdog_task
      kworker/4:0-9357  [004] ...1 471985.266393: igb_rd32 
<-igb_ptp_rx_hang

I'm not sure if it's helpful, but it's the only thing I got.

Just to check, this is the way I'm reading the ftrace:

echo function | sudo tee /sys/kernel/debug/tracing/current_tracer; for i 
in $(seq 1 10); do sudo cat /sys/kernel/debug/tracing/trace | grep -C3 
igb_ptp; done; echo nop | sudo tee /sys/kernel/debug/tracing/current_tracer

In January, I'll be able to provide ftrace comparison with the working 
igb card.

Thanks for further guidance here.

Martin

--
Mgr. Martin Pecka, Ph.D.
Researcher at Vision for Robotics and Autonomous Systems group
Faculty of Electrical Engineering
Czech Technical University in Prague
Phone: +420 22435 7269