On Wed, Oct 13, 2021 at 08:37:27PM +0300, Vladimir Oltean wrote: > The other topic is how to actually wait for phc2sys to synchronize, > since the program presented here only works with ptp4l (or at least > that's all I tested).
If it is the system clock, phc2sys clears the STA_UNSYNC flag (which is reported by ntp_gettime()/ntp_adjtime()) when the servo is in the locked state. There is the esterror (and potentially also maxerror) field, which could be set by ptp4l/phc2sys to some estimate of the error. Any application could easily check the value to decide if the clock is good enough for its purposes. No need to implement PTP or have access to the ptp4l/phc2sys socket. I think it would be great if all PTP clocks had this status and esterror/maxerror fields. For example, with the ptp_kvm driver guests have access to the system clock of the host as a PHC, but there is no way to check if/how well the clock is actually synchronized. I had this on my todo list for a long time, but wasn't able to look into it yet. -- Miroslav Lichvar _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
