Re: [PATCH 7/7] net: dsa: b53: Expose PTP timestamping ioctls to userspace

[Vladimir Oltean]

On Fri, 26 Nov 2021 at 18:31, Richard Cochran <richardcochran@xxxxxxxxx> wrote:
>
> On Fri, Nov 26, 2021 at 09:42:32AM +0100, Kurt Kanzenbach wrote:
> > On Thu Nov 25 2021, Vladimir Oltean wrote:
> > > Richard, when the request is PTP_V2_EVENT and the response is
> > > PTP_V2_L2_EVENT, is that an upgrade or a downgrade?
> >
> > It is a downgrade, isn't it?
>
> Yes.  "Any kind of PTP Event" is a superset of "Any Layer-2 Event".
>
> When userland asks for "any kind", then it wants to run PTP over IPv4,
> IPv6, or Layer2, maybe even more than one at the same time.  If the
> driver changes that to Layer2 only, then the PTP possibilities have
> been downgraded.

Well, when I said that it's essentially the same pattern, this is what
I was talking about. The b53 driver downgrades everything and the
kitchen sink to HWTSTAMP_FILTER_PTP_V2_L2_EVENT, the ocelot driver to
HWTSTAMP_FILTER_PTP_V2_EVENT, and both are buggy for the same reason.
I don't see why you mention that there is an important difference
between HWTSTAMP_FILTER_PTP_V2_L2_EVENT and
HWTSTAMP_FILTER_PTP_V2_EVENT. I know there is, but the _pattern_ is
the same.
I'm still missing something obvious, aren't I?