On Tue, Mar 15, 2022 at 06:11:26AM -0700, Axel Simon wrote: > Is there something I'm missing here? Is there any documentation or > recommendation regarding the design of a high-accuracy linuxptp-based system?
No, you stated the facts well enough. If you want to make a single port GM, then you might want to provide it with a global time source. Let's assume you are using the i210. You have some choices. 1. Configure the i210 as --free_running=1 (not a global time source at all. But it might be okay to synchronize a "time island" depending on your application requirements). 2. Run NTP client on the Linux host, and use phc2sys to sync PHC with Linux system time. Might end up milliseconds offset from global time due to NTP performance alone. 3. Attach GPS PPS to, say, Linux serial port, and use phc2sys to sync PHC with Linux system time. Not a great solution, because of poor time stamps from the Linux kernel PPS subsystem. 4. Attach GPS PPS to i210 SDP. This is the best solution. With a healthy GPS fix, your GM will be easily within a few hundred nanoseconds of global time. That is without any special tuning. Now, if your GM has more than one port, then of course you will want to use design #4 and feed the PPS to i210 cards in parallel. (Alternately you could feed PPS into one card, then generate a PPS from that card to the others.) It is your design. You have your application requirements. You can make whatever engineering decisions you wish. But please don't spread FUD about linuxptp. Thanks, Richard _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users
