Re: [PATCH net-next v2 0/2] net: dsa: mv88e6xxx: various hwstamp fixes

[Luke Howard]

>> Good point. So perhaps processing the embedded timestamp inline
>> doesn’t confer much benefit. ptp4l (which we use) handles out-of-order
>> messages fine.
> 
> If you're intending the in-band timestamps as a fix for gptp2d's
> limitations, then no. As a general optimization - maybe.

Delivering it inline makes more sense to me but it is a more intrusive change. I don’t have a strong opinion either way. I’m sure gptp2d could be fixed were someone motivated.

> The only problem with timecounter/cyclecounter is that the hardware
> clock remains free-running, which means you won't be able to apply a
> time-synchronized taprio schedule (if the hw supports that).

Yes, many Marvell switches support 802.1Qbv but there is no kernel support at this time. For 802.1AS, you want both kernel and user counters to be free running, so neighborRateRatio can be correctly reported.

Luke