On Thu, Jun 21, 2018 at 02:36:02PM +0200, Miroslav Lichvar wrote: > On Thu, Jun 21, 2018 at 12:24:15AM -0700, Rob Cornall wrote: > > I know for a different nic like the i210, it has some specific SDPs that > > can be used > > for the PPS input - and this could be used to discipline the phc in the nic > > directly.
IIRC the imx also has input pins. > A bigger problem might be with the PPS timestamping. I'm not sure how > exactly it works with the imx. If the kernel is timestamping > interrupts triggered by the PPS, that will probably add an error of at > least few microseconds, maybe even few tens of microseconds. Unless > you can measure the delay and make sure it's stable, 1us accuracy is > not realistic. Right. The delay from interrupt to interrupt handler can be even hundreds of usec, at it will have jitter. > The PPS needs to be timestamped by the HW (like with the i210), or by > the kernel polling the GPIO pin (assuming the reading is fast enough). Right. Thanks, 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
