netdev - Re: [PTP][KSZ9477][p2p1step] Questions for PTP support on KSZ9477 device

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Message-ID: <aFJJlGzu4DrmqH3P@hoboy.vegasvil.org>
Date: Tue, 17 Jun 2025 22:07:32 -0700
From: Richard Cochran <richardcochran@...il.com>
To: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	Lukasz Majewski <lukma@...x.de>, netdev@...r.kernel.org,
	Arun Ramadoss <arun.ramadoss@...rochip.com>,
	Vladimir Oltean <olteanv@...il.com>, Tristram.Ha@...rochip.com,
	Christian Eggers <ceggers@...i.de>
Subject: Re: [PTP][KSZ9477][p2p1step] Questions for PTP support on KSZ9477
 device

On Tue, Jun 17, 2025 at 05:10:11PM +0100, Vadim Fedorenko wrote:
> On 17/06/2025 06:25, Oleksij Rempel wrote:
> > No, this will not work correctly. Both sides must use the same timestamping
> > mode: either both "one step" or both "two step".
> 
> I'm not quite sure this statement is fully correct. I don't have a
> hardware on hands to make this setup, but reading through the code in
> linuxptp - the two-step fsm kicks off based on the message type bit. In case
> when linuxptp receives 1-step sync, it does all the calculations.

Correct.

> For delay response packets on GM side it doesn't matter as GM doesn't do
> any calculations. I don't see any requirements here from the perspective
> of protocol itself.

Running on a PTP client, ptp4l will happily use either one or two step
Sync messages from the server.

Thanks,
Richard