[Linuxptp-users] Interesting (very wrong) PTP output

[Keller, J. E <jac...@in...>]

n0825:[1]/root/linuxptp> ./ptp4l -m -v -P -f default.cfg -i eth2
ptp4l[28757]: selected /dev/ptp0 as PTP clock

ptp4l[28757]: port 1: INITIALIZING to LISTENING on INITIALIZE
ptp4l[28757]: port 1: new foreign master 001b21.fffe.cf83e4-1
ptp4l[28757]: selected best master clock 001b21.fffe.cf83e4
ptp4l[28757]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE
ptp4l[28757]: master offset 8053809267140 s0 adj      +0 path delay     -58248
ptp4l[28757]: master offset 8052809280419 s0 adj      +0 path delay     -55403
ptp4l[28757]: master offset 8051809142574 s0 adj      +0 path delay     -56020
ptp4l[28757]: master offset 8050809162084 s1 adj      +0 path delay     -56020
ptp4l[28757]: master offset -1000134414 s2 adj -250000000 path delay     -56427
ptp4l[28757]: port 1: UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED
ptp4l[28757]: master offset -750413376 s2 adj -250000000 path delay     -56427
ptp4l[28757]: master offset -500400801 s2 adj -250000000 path delay     -44558
ptp4l[28757]: master offset -250420149 s2 adj -250000000 path delay     -36052
ptp4l[28757]: master offset    -393488 s2 adj -250000000 path delay     -36052
ptp4l[28757]: master offset  249589808 s2 adj -250000000 path delay     -29589
ptp4l[28757]: master offset  499591481 s2 adj -250000000 path delay      -5666
ptp4l[28757]: master offset  749574326 s2 adj -250000000 path delay        798
ptp4l[28757]: master offset  999593422 s2 adj -250000000 path delay       8104
ptp4l[28757]: master offset 1249583788 s2 adj -250000000 path delay       8104
ptp4l[28757]: master offset 1499600752 s2 adj -250000000 path delay      15263
ptp4l[28757]: master offset 1749590329 s2 adj -250000000 path delay      15263
ptp4l[28757]: master offset 1999616415 s2 adj -250000000 path delay      15287
ptp4l[28757]: master offset 2249605370 s2 adj -250000000 path delay      15281
ptp4l[28757]: master offset 2499629742 s2 adj -250000000 path delay      15285
ptp4l[28757]: master offset 2749620793 s2 adj -250000000 path delay      15291

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This occurs sometimes after running a script that tests a bunch of ethtool commands. The result seems to be due to the -250m ppb adjustment never gets reset. However when I reperform the test, and instead of using the script before starting PTP, I force the offset to be a similar value by using testptp script to force clock adjustment, the restult is correct (it calculates the necessary large offset and then works fine)

If I re-run the test again but force the 2nd machine to be slave, I get the reverse results: adj is +250000000 but the offset from master continually increases with no sign of converging.

It seems like somehow the p/i servo code is incorrect because once we hit max adjust it never seems to move away from it. However that isn't the case when I run ptp4l without that script. I am still trying to determine what the script is doing to the ptp registers on the device (if anything)

- Jake