Re: [Linuxptp-users] A10 SoC ptp4l - can't resync after losing GM

[John L. <joh...@fo...>]

Richard,

Thanks for the response.  I should have said before, we are using 802.1AS
and I have the 'gmCapable' set to 0, but it has no effect and the OC slave
still assumes the GM role.  Shouldn't that setting stop it from ever
assuming the GM role?  Maybe I'm missing something there about the BMC
algorithm.

I did a test while capturing all packets at the A10 slave.  It starts with
the units being in sync, then I disconnect the GM and plug it back in
about 15 seconds later.  As far as the Announce messages, the GM is
sending an announce message every second while it's connected, and then
once it's reconnected they actually do sync up briefly.  Then about 5
seconds after re-sync - the slave transmits an Announce message and then
starts sending Sync/Follow up messages, and I don't see another Announce
from the GM up until I stopped the capture.  

I did indeed notice if I bring the mac down and back up - it resyncs fine.



John


-----Original Message-----
From: Richard Cochran <ric...@gm...> 
Sent: Thursday, February 14, 2019 9:23 PM
To: John Lemonovich <joh...@fo...>
Cc: lin...@li...
Subject: Re: [Linuxptp-users] A10 SoC ptp4l - can't resync after losing GM

On Thu, Feb 14, 2019 at 09:54:42AM -0600, John Lemonovich wrote:
> I have been running ptp4l on various intel FPGA Arria 10 SoC 
> implementations, including one with the 10Gb MAC and a few with the 
> HPS EMAC (stmmicro 1GbE) and it's all working very well.  One issue 
> we're seeing is, if our A10 slave has been sync'd with a GM clock, and 
> then that GM goes away (power cycled or even cable 
> disconnected/reconnected) - our
> A10 ptp4l app won't resync to that same GM.  When the cable is 
> reconnected, ptp4l does indeed select that same GM briefly as the BMC, 
> but then it loses it upon announce receipt timeout expires and it 
> never comes back.  I tried higher thresholds for 
> annoucereceipttimeout, but it didn't help.

Use tcpdump to see whether Announce messages are missing.

Thanks,
Richard