Not directly related to this, but ... Having spent some time modifying the FEC driver, I can highlight some things to be aware of 1. The hardware nanosecond counter is not the same as PTP nanoseconds. PTP time is held as a variable, not by FEC 2. The PPS-OUT signal does fire each second, but is not necessarily aligned to PTP 0 nanoseconds 3. MAC/PHY resets will kill PPS-OUT (eg link down/up) 4. To get sub 100ns accuracy, you're likely going to need external hardware to control the system clock by measuring the difference between GPS-PPS and PPS-OUT. (You can then do fine adjustment of PTP time) 5. In my experience, PPS-in via GPIO just has far too much jitter to be useful.
Regards Richard (H) -----Original Message----- From: Richard Cochran [mailto:richardcoch...@gmail.com] Sent: Samstag, 23. Juni 2018 03:25 To: Rob Cornall Cc: linuxptp-users@lists.sourceforge.net Subject: Re: [Linuxptp-users] Grandmaster with gps pps On Sat, Jun 23, 2018 at 12:40:33AM +0000, Rob Cornall wrote: > Another question about connecting the PPS, It does look like there are input > pins on imx6 FEC, > Do I only need to connect the 1PPS to said pin? Not only that, but you'll have to get the time stamps and use them to discipline to PHC. > Also it doesn't look like the imx6 fec_ptp driver supports input PPS for > Grand master support, > do you if any work is happening for this? I thought that has been done already, but I just took a look at mainline and net-next linux, and it hasn't been done. I don't know if anyone is working this either. Sorry, Richard ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users
