using phc2sys, there is a fixed 0.5ms offset between the system time and phc time

[zhupidong]

hi: I want to set system time with phc time. Use the following command：

1. ts2phc -f ts2phc.cfg -m -s nmea -l 7
2. phc2sys -d /dev/pps0 -s dpni.0 -c CLOCK_REALTIME -m -O 0 -S 5

phc2sys output is phc2sys[62092.093]: CLOCK_REALTIME pps offset -1158 s2 freq -3041 phc2sys[62093.093]: CLOCK_REALTIME pps offset 643 s2 freq -1587 phc2sys[62094.093]: CLOCK_REALTIME pps offset 391 s2 freq -1647 phc2sys[62095.093]: CLOCK_REALTIME pps offset 917 s2 freq -1003 phc2sys[62096.093]: CLOCK_REALTIME pps offset -1159 s2 freq -2804 phc2sys[62097.093]: CLOCK_REALTIME pps offset -395 s2 freq -2388 phc2sys[62098.093]: CLOCK_REALTIME pps offset 313 s2 freq -1798 phc2sys[62099.093]: CLOCK_REALTIME pps offset -168 s2 freq -2185 phc2sys[62100.093]: CLOCK_REALTIME pps offset -543 s2 freq -2611 phc2sys[62101.093]: CLOCK_REALTIME pps offset 629 s2 freq -1602 phc2sys[62102.093]: CLOCK_REALTIME pps offset 510 s2 freq -1532 phc2sys[62103.093]: CLOCK_REALTIME pps offset -557 s2 freq -2446 phc2sys[62104.093]: CLOCK_REALTIME pps offset 809 s2 freq -1247 phc2sys[62105.093]: CLOCK_REALTIME pps offset 1656 s2 freq -157 phc2sys[62106.093]: CLOCK_REALTIME pps offset -2026 s2 freq -3343 phc2sys[62107.093]: CLOCK_REALTIME pps offset -443 s2 freq -2367 phc2sys[62108.093]: CLOCK_REALTIME pps offset -435 s2 freq -2492 phc2sys[62109.093]: CLOCK_REALTIME pps offset -223 s2 freq -2411 phc2sys[62110.093]: CLOCK_REALTIME pps offset 628 s2 freq -1627 phc2sys[62111.093]: CLOCK_REALTIME pps offset 695 s2 freq -1371 phc2sys[62112.093]: CLOCK_REALTIME pps offset -693 s2 freq -2551 phc2sys[62113.093]: CLOCK_REALTIME pps offset -782 s2 freq -2848 phc2sys[62114.093]: CLOCK_REALTIME pps offset 906 s2 freq -1394 phc2sys[62115.093]: CLOCK_REALTIME pps offset 460 s2 freq -1569 phc2sys[62116.093]: CLOCK_REALTIME pps offset -651 s2 freq -2542 phc2sys[62117.093]: CLOCK_REALTIME pps offset 131 s2 freq -1955 phc2sys[62118.093]: CLOCK_REALTIME pps offset -34 s2 freq -2081 phc2sys[62119.093]: CLOCK_REALTIME pps offset 1167 s2 freq -890 phc2sys[62120.093]: CLOCK_REALTIME pps offset -983 s2 freq -2690

but when I use the testptp to calculate the offset between system time and phc, I find that there is a fixed 0.5ms offset between the system time and phc time

[root@aarch64 /home/user/zjl]# ./testptp -k 3 system and phc clock time offset request okay system time: 1667874466.435949440 phc time: 1667874466.436529180 system time: 1667874466.435963000 system/phc clock time offset is -572960 ns system clock time delay is 13560 ns system time: 1667874466.435963000 phc time: 1667874466.436530510 system time: 1667874466.435964320 system/phc clock time offset is -566850 ns system clock time delay is 1320 ns system time: 1667874466.435964320 phc time: 1667874466.436531790 system time: 1667874466.435965720 system/phc clock time offset is -566770 ns system clock time delay is 1400 ns

How to eliminate this deviation,thank you.