Re: [PATCH net-next v6 4/7] net: dsa: hellcreek: Add support for hardware timestamping

On Tue, Oct 06, 2020 at 03:30:36PM +0200, Kurt Kanzenbach wrote:

That's the point. The user (or anybody else) cannot disable hardware
stamping, because it is always performed. So, why should it be allowed
to disable it even when it cannot be disabled?

Because your driver's user can attach a PTP PHY to your switch port, and
the network stack doesn't support multiple TX timestamps attached to the
same skb. They'll want the TX timestamp from the PHY and not from your
switch.