Re: [PATCH net-next 0/5] PTP support for the SJA1105 DSA driver

[Vladimir Oltean]

On Thu, 30 May 2019 at 18:06, Richard Cochran <richardcochran@xxxxxxxxx> wrote:
>
> On Thu, May 30, 2019 at 05:57:30PM +0300, Vladimir Oltean wrote:
> > On Thu, 30 May 2019 at 17:30, Richard Cochran <richardcochran@xxxxxxxxx> wrote:
> > >
> > > Not necessarily.  If two frames that arrive at nearly the same time
> > > get their timestamps mixed up, that would be enough to break the time
> > > values but without breaking your state machine.
> > >
> >
> > This doesn't exactly sound like the type of thing I can check for.
>
> And that is why it cannot work.
>
> > The RX and TX timestamps *are* monotonically increasing with time for
> > all frames when I'm printing them in the {rx,tx}tstamp callbacks.
>
> But are the frames received in the same order?  What happens your MAC
> drops a frame?
>

If it drops a normal frame, it carries on.
If it drops a meta frame, it prints "Expected meta frame", resets the
state machine and carries on.
If it drops a timestampable frame, it prints "Unexpected meta frame",
resets the state machine and carries on.
This doesn't happen under correct runtime conditions though.

-Vladimir

> > The driver returns free-running timestamps altered with a timecounter
> > frequency set by adjfine and offset set by adjtime.
>
> That should be correct.
>
> Thanks,
> Richard