Re: [Linuxptp-users] Sync does not converge over switch with KSZ9477 in E2E TC mode

[Richard C. <ric...@gm...>]

On Tue, Jun 28, 2022 at 03:21:02PM +0200, Martin Pecka wrote:

> - according to one user, for P2P to work over this switch, it might be
> required to connect a host CPU to the MII port. I don't quite understand why
> it should be a different port that would be creating the PDelay messages on
> regard of the downstream ports, but that would quite plausibly explain the
> behavior of the switch (but would not explain why the datasheet tells it can
> act as P2P TC, if it actually needs a linux computer next to it to gain this
> functionality).

Most (all?) TCs need a micro-processor or micro-controller to handle the PTP.
PTP is just too complicated to do in hardware.

The peer messages must be generated per-port, and some program need to
do that.  When used with DSA switches, ptp4l can do this work.

Thanks,
Richard