Re: [PATCH net-next v3 0/3] net: dsa: mv88e6xxx: various hwstamp fixes

[Luke Howard]

> On 25 Jul 2026, at 09:52, Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
> 
> On Sun, 19 Jul 2026 15:30:52 +1000 Luke Howard wrote:
>> Three fixes for improving the reliably of hardware timestamp acquisition
>> on Marvell switches. In our tests this eliminated missed timestamps in
>> ptp4l, whilst also preserving PTP event and general message ordering on
>> switches that support embedded timestamps.
> 
> Do you know if there's any precedent in the existing upstream drivers
> for overriding the reserved bytes? It's not normal for devices to modify
> the ingress frames. Perhaps there's some precedent, but if not I think
> we should gate this (eg with a devlink param?)
> 
> Andrew, do you have any opinion? Or perhaps Richard?

See hellcreek_get_rxts() in drivers/net/dsa/hirschmann/hellcreek_hwtstamp.c.

In any case, Vladimir proposes to gate with a new DSA tag protocol (I haven’t heard any objections to this). I will include this in the next revision, I just have not had an opportunity to test.
 
>> Note: squashing the two embedded timestamp patches into a single commit
>> may be desirable.
> 
> I think it would be great to invert the order. Revamp the locking as
> patch 2 then add the new feature as patch 3.

Can do.

Luke