On Tue, 10 Oct 2023 10:23:43 +0200 Köry Maincent wrote:
> > > +/*
> > > + * Hardware layer of the TIMESTAMPING provider
> > > + * New description layer should have the NETDEV_TIMESTAMPING or
> > > + * PHYLIB_TIMESTAMPING bit set to know which API to use for timestamping.
> >
> > If we are talking about hardware layers, then we shall use either
> > PHY_TIMESTAMPING or MAC_TIMESTAMPING. PHYLIB is the sub-subsystem to
> > deal with Ethernet PHYs, and netdev is the object through which we
> > represent network devices, so they are not even quite describing similar
> > things. If you go with the {PHY,MAC}_TIMESTAMPING suggestion, then I
> > could see how we could somewhat easily add PCS_TIMESTAMPING for instance.
>
> I am indeed talking about hardware layers but I updated the name to use NETDEV
> and PHYLIB timestamping for a reason. It is indeed only PHY or MAC timestamping
> for now but it may be expanded in the future to theoretically to 7 layers of
> timestamps possible. Also there may be several possible timestamp within a MAC
> device precision vs volume.
> See the thread of my last version that talk about it:
> https://lore.kernel.org/netdev/20230511203646.ihljeknxni77uu5j@skbuf/
>
> All these possibles timestamps go through exclusively the netdev API or the
> phylib API. Even the software timestamping is done in the netdev driver,
> therefore it goes through the netdev API and then should have the
> NETDEV_TIMESTAMPING bit set.
Netdev vs phylib is an implementation detail of Linux.
I'm also surprised that you changed this.
> > > + */
> > > +enum {
> > > + NO_TIMESTAMPING = 0,
> > > + NETDEV_TIMESTAMPING = (1 << 0),
> > > + PHYLIB_TIMESTAMPING = (1 << 1),
> > > + SOFTWARE_TIMESTAMPING = (1 << 2) | (1 << 0),
> >
> > Why do we have to set NETDEV_TIMESTAMPING here, or is this a round-about
> > way of enumerating 0, 1, 2 and 3?
>
> I answered you above the software timestamping should have the
> NETDEV_TIMESTAMPING bit set as it is done from the net device driver.
>
> What I was thinking is that all the new timestamping should have
> NETDEV_TIMESTAMPING or PHYLIB_TIMESTAMPING set to know which API to pass
> through.
> Like we could add these in the future:
> MAC_DMA_TIMESTAMPING = (2 << 2) | (1 >> 0),
> MAC_PRECISION_TIMESTAMPING = (3 << 2) | (1 >> 0),
> ...
> PHY_SFP_TIMESTAMPING = (2 << 2) | (1 << 1),
> ...
What is "PRECISION"? DMA is a separate block like MAC and PHY.
