On Fri, Sep 09, 2022 at 08:45:19AM +0800, Hamilton Alex wrote: > Hi, Richard: > I am not quite understand. I am using Calnex master-->board slave, if the > linuxptp print out is correct, that means local clock > has the same frequency and phase as master clock, then the 1PPS out should > near the reference 1PPS. > > why path asymmetry would affect the 1PPS out?
You reported a 40 nanosecond phase offset. One possible cause is path asymmetry. The PTP assumes the Tx and Rx transmission delays are exactly equal. However, this is almost never true. Any real asymmetry results in a phase offset that is uncorrectable by the PTP. Because your 40 ns phase offset is very small, you might very well have path asymmetry somewhere in your system. For example, your PHY might delay frames longer on Tx than on Rx. HTH, Richard _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
