Hi Joseph, On Mon, May 24, 2021 at 03:21:14PM -0700, Jacob Keller wrote: > On 5/24/2021 2:06 AM, Joseph Matan wrote: > > The kernel version I'm using (v4.19) doesn't support the gettimex > > implementation, so I've added this patch: > > More accurate PHC<->system clock synchronization > > <https://patchwork.ozlabs.org/project/netdev/cover/20181109101449.15398-1-mlich...@redhat.com/> > > (I > > only took patches 1-4/8) > > But this patch doesn't include my KSZ driver (patches 5-8/8 include only > > other drivers), so I had to add my own implementation to the KSZ driver > > in order to support the PTP_SYS_OFFSET_EXTENDED ioctl. > > Unfortunately, it didn't help, and I still suffer from huge delays and > > offsets (I did verify the ptp4l is running the SYSOFF_METHOD method). > > > > Any other ideas or tips ? > > > > Thanks for the help, > > Joseph > > Unfortunately no. That gettimex bits worked ok for Intel hardware > because we have to read 2 (or 3) registers, and the time is locked by > reading the lowest register. By using system time captures around that > low register read we get a more accurate comparison. > > Unfortunately if this doesn't help your case, I am not sure what else > would be worth trying. > > One possibility is to attempt to tune the servo parameters (The P and I > constant values for the PI servo, for example). You might be able to > find slightly better values that are less sensitive to the delay. It is > likely this would take longer to converge but could produce a more > smooth result at the end. > > You might also try one of the other servo algorithms such as linreg. > > Unfortunately if reading the clock time of your device has high jitter > it will produce worse results. There's not much way around that.
Some ideas on how MDIO accesses can be made faster and more predictable: disable transmission of preamble, increase frequency, use polled I/O for the MDIO controller (you probably already do, unless you use i.MX devices which are the only ones handling interrupts in mdio_read/write). Additionally, if you have some time to spend with the mainline Linux kernel, you can pick up and resubmit some patches that propagate struct ptp_system_timestamp into the MDIO controller and allow software timestamps to be one order of magnitude more precise. Some more details and links here: https://github.com/openil/linuxptp/issues/5#issuecomment-615979496 _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users
