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

[Luke Howard]

> On 28 Jul 2026, at 06:18, Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
> 
> On Sat, 25 Jul 2026 17:54:53 +0200 Andrew Lunn wrote:
>> On Fri, Jul 24, 2026 at 04:52:07PM -0700, Jakub Kicinski 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?  
>> 
>> I have a dim memory of PHYs who change the packet by adding time
>> stamps. There are definitely DSA switches which can put the stamps in
>> the DSA header/trailer.
> 
> Ack, thanks! To clarify I of course don't mind modification one-step
> timestamping style (Tx). But here we're overriding reserved protocol
> fields to carry local metadata (Rx).
> 
> Let's see v4..

v4 was posted on 27 July [1], I’m wondering if there is any feedback?

Cheers,
Luke

[1] https://lore.kernel.org/all/20260727-mv88e6xxx-ptp-fixes-v4-0-10b4020155fc@xxxxxxxx/