[Linuxptp-users] The ptp4l is not sync sometimes.

[Takahiro S. <tsh...@gm...>]

Hello,

I am trying ptp4l with Intel EG20T.
ptp4l is not sync sometimes, when we transfer many data simultaneously like
follwoing.

ptp4l[17353]: master offset          2 s2 adj +32755854 path delay
2942
ptp4l[17353]: master offset         31 s2 adj +32755883 path delay
2945
ptp4l[17353]: master offset        -33 s2 adj +32755828 path delay
2945
ptp4l[17353]: master offset         31 s2 adj +32755883 path delay
2945
ptp4l[17353]: master offset         -1 s2 adj +32755860 path delay
2945
ptp4l[17353]: master offset        -41 s2 adj +32755820 path delay
2953
ptp4l[17353]: master offset         -8 s2 adj +32755840 path delay
2952
ptp4l[17353]: master offset         56 s2 adj +32755902 path delay
2952
ptp4l[17353]: master offset        -14 s2 adj +32755849 path delay
2958
ptp4l[17353]: master offset -55176644235214 s2 adj -50000000 path delay
  2958
ptp4l[17353]: negative path delay -27588322110544
ptp4l[17353]: path_delay = (t2 - t3) + (t4 - t1)
ptp4l[17353]: t2 - t3 = -55177301241888
ptp4l[17353]: t4 - t1 = +657020800
ptp4l[17353]: c1          0
ptp4l[17353]: c2          0
ptp4l[17353]: c3          0
ptp4l[17353]: master offset 2758832199206 s2 adj +50000000 path delay
-2758832208390
ptp4l[17353]: master offset 2758832186448 s2 adj +50000000 path delay
-2758832207792
ptp4l[17353]: master offset 2758832174544 s2 adj +50000000 path delay
-2758832207792
ptp4l[17353]: master offset 2758832161990 s2 adj +50000000 path delay
-2758832207590
ptp4l[17353]: master offset 2758832149267 s2 adj +50000000 path delay
-2758832206995
ptp4l[17353]: master offset 2758832137072 s2 adj +50000000 path delay
-2758832206960
ptp4l[17353]: master offset 2758832124875 s2 adj +50000000 path delay
-2758832206891
ptp4l[17353]: master offset 2758832112171 s2 adj +50000000 path delay
-2758832206379
ptp4l[17353]: master offset 2758832100043 s2 adj +50000000 path delay
-2758832206379
ptp4l[17353]: master offset 2758832087416 s2 adj +50000000 path delay
-2758832205880
ptp4l[17353]: master offset    -136851 s2 adj +32619007 path delay
6259
ptp4l[17353]: master offset       -179 s2 adj +32714624 path delay
6259
ptp4l[17353]: negative path delay      -7904
ptp4l[17353]: path_delay = (t2 - t3) + (t4 - t1)
ptp4l[17353]: t2 - t3 = -507698240
ptp4l[17353]: t4 - t1 = +507682432
ptp4l[17353]: c1          0
ptp4l[17353]: c2          0
ptp4l[17353]: c3          0
ptp4l[17353]: negative path delay      -9136
ptp4l[17353]: path_delay = (t2 - t3) + (t4 - t1)
ptp4l[17353]: t2 - t3 = -566457632
ptp4l[17353]: t4 - t1 = +566439360
ptp4l[17353]: c1          0
ptp4l[17353]: c2          0
ptp4l[17353]: c3          0
ptp4l[17353]: master offset      44452 s2 adj +32759201 path delay
3164
ptp4l[17353]: master offset      40900 s2 adj +32768985 path delay
3164
ptp4l[17353]: master offset      28141 s2 adj +32768496 path delay
3795
ptp4l[17353]: master offset      15981 s2 adj +32764778 path delay
3795
ptp4l[17353]: master offset       6644 s2 adj +32760236 path delay
4204
ptp4l[17353]: master offset       2640 s2 adj +32758225 path delay
3856
ptp4l[17353]: master offset        272 s2 adj +32756649 path delay
3856
ptp4l[17353]: master offset        -11 s2 adj +32756447 path delay
3371
ptp4l[17353]: master offset       -201 s2 adj +32756254 path delay
2985
ptp4l[17353]: master offset       -233 s2 adj +32756162 path delay
2569
ptp4l[17353]: master offset      -1025 s2 adj +32755300 path delay
3105
ptp4l[17353]: master offset       -705 s2 adj +32755312 path delay
3105
ptp4l[17353]: master offset      -1126 s2 adj +32754680 path delay
4294
ptp4l[17353]: master offset        212 s2 adj +32755680 path delay
4140
ptp4l[17353]: master offset       1002 s2 adj +32756534 path delay
3542
ptp4l[17353]: master offset        727 s2 adj +32756559 path delay
3145
ptp4l[17353]: master offset        114 s2 adj +32756164 path delay
3022
ptp4l[17353]: master offset       -153 s2 adj +32755932 path delay
3033
ptp4l[17353]: master offset       -248 s2 adj +32755791 path delay
3032
ptp4l[17353]: master offset       -169 s2 adj +32755795 path delay
3017
ptp4l[17353]: master offset       -105 s2 adj +32755809 path delay
3017
ptp4l[17353]: master offset        -28 s2 adj +32755854 path delay
3004

I chedked t1, .. t4 value.
t2 or t4 is 0 at the time.

ptp4l[20494]: negative path delay -45370388164880
ptp4l[20494]: path_delay = (t2 - t3) + (t4 - t1)
ptp4l[20494]: t2 - t3 = -90741482576736
ptp4l[20494]: t4 - t1 = +706246976
ptp4l[20494]: t1 = +90740776333280
ptp4l[20494]: t2 =         +0
ptp4l[20494]: t3 = +90741482576736
ptp4l[20494]: t4 = +90741482580256
ptp4l[20494]: c1          0
ptp4l[20494]: c2          0
ptp4l[20494]: c3          0

I think EG20T ieee1588 hardware is independent from the GbE hardware.
The GbE driver get the timestamp from ieee1588 hardware.
If the 2 PTP messages are received in short period and the GbE driver can
not get the timestamp in fast response, the timestamp of 2nd message can
not be locked and the value is 0.

So I modify the ptp4l as follows. Please see "TS add here".

---
void clock_path_delay(struct clock *c, struct timespec req, struct
timestamp rx,
:
if (pd < 0) {
pr_warning("negative path delay %10lld", pd);
pr_warning("path_delay = (t2 - t3) + (t4 - t1)");
pr_warning("t2 - t3 = %+10lld", t2 - t3);
pr_warning("t4 - t1 = %+10lld", t4 - t1);
pr_warning("t1 = %+10lld", t1);
pr_warning("t2 = %+10lld", t2);
pr_warning("t3 = %+10lld", t3);
pr_warning("t4 = %+10lld", t4);
pr_warning("c1 %10lld", c1);
pr_warning("c2 %10lld", c2);
pr_warning("c3 %10lld", c3);
return; // TS add here
}

enum servo_state clock_synchronize(struct clock *c,
:
if ((origin != 0) && (ingress != 0)) // TS add here
c->master_offset = tmv_sub(ingress,
tmv_add(origin, tmv_add(c->path_delay, tmv_add(c->c1, c->c2))));

---

This means if t1, .. t4 are 0, ptp4l will not update master_offset and
path_delay.
After modification, ptp4l is sync always with Intel EG20T hardware.

My questions are:

1. Intel EG20T ieee1588 is similar ixp4xx. Did anyone face the similar
issue?
2. Is my modification correct?

Thanks and Best regards,
Takahiro Shimizu