Re: [PATCH net] net: ethernet: ti: am65-cpts: keep port and direction when matching PTPv1 TX timestamps

[Siddharth Vadapalli]

On 11/2/26 7:05 PM, Jesper Lyager Nielsen wrote:
> Hi Siddharth,
>
> Thanks for looking at this.
>
> On 10/30/26 ..., Siddharth Vadapalli wrote:
> > > For PTPv1 this defeats
> > > commit a23c657e332f ("net: ethernet: ti: am65-cpsw: Use also port number to identify timestamps").
> >
> > nitpick: This could be wrapped as done for the previous instance above.
>
> Will do in v2.
>
> > > With a PTPv1 master on both ports
> > > whose sequence ids run in step (e.g. a Dante device with primary and
> >
> > Does this mean there are two PTP grandmasters? Is CPSW configured in EMAC
> > mode or Switch mode? Is the PTP application bound to both network
> > interfaces?
>
> CPSW is in multi-port MAC (EMAC) mode: eth0 and eth1 are separate
> interfaces with their own addresses on two physically separate networks,
> there is no bridge between them.
>
> This is Dante network redundancy. The audio device is connected to a
> primary network (eth1) and a completely separate secondary network
> (eth0), and every Dante device sends the same audio on both. There is a
> single PTP application (Audinate's PTPv1 daemon), one process bound to
> both interfaces, using hardware timestamps on both.
>
> So there is one clock, the CPTS, and one PTP instance. When that device
> is elected leader, it is the master on each of the two networks, with
> each port sending Sync/Follow_Up into its own network, both timestamped
> by the same CPTS. Each network has exactly one master; it is the same
> device and the same time base on both, much like a boundary clock or
> ptp4l with two ports sharing one PHC.
>
> The daemon keeps a sequence counter per port. When both ports start at
> the same time, the counters run in step, so Sync N leaves on eth0 and
> eth1 within microseconds of each other. That is when the same-seqid
> event of the other port can be matched.

Thank you for explaining. The motivation for this patch and the problem it 
fixes is clear to me now.

> > nitpick: Unlike other subsystems, comments in netdev do not have an empty
> > line at the start.
>
> Will fix in v2. I'll wait for your review of the code before sending it.

The code looks good to me. With the nitpicks addressed,

Reviewed-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>

Regards,
Siddharth.