On Sat, 1 Jun 2019 at 08:07, Richard Cochran <richardcoch...@gmail.com> wrote: > > On Fri, May 31, 2019 at 09:12:03PM +0300, Vladimir Oltean wrote: > > It won't work unless I make changes to dsa_switch_rcv. > > Or to the tagging code. > > > Right now taggers can only return a pointer to the skb, or NULL, case > > in which DSA will free it. > > The tagger can re-write the skb. Why not reform it into a PTP frame? > This clever trick is what the phyter does in hardware. See dp83640.c. >
I think you're missing the point here. If I dress the meta frame into a PTP frame (btw is there any preferable event message for this purpose?) then sure, I'll make dsa_skb_defer_rx_timestamp call my .port_rxtstamp and I can e.g. move my state machine there. The problem is that in the current DSA structure, I'll still have less timestampable frames waiting for a meta frame than meta frames themselves. This is because not all frames that the switch takes an RX timestamp for will make it to my .port_rxtstamp (in fact that is what my .can_timestamp patch changes). I can put the timestampable frame in a 1-entry wait queue which I'll deplete upon arrival of the first meta frame, but when I get meta frames and the wait queue is empty, it can mean multiple things: either DSA didn't care about this timestamp (ok), or the timestampable frame got reordered or dropped by the MAC, or what have you (not ok). So I can't exclude the possibility that the meta frame was holding a relevant timestamp. Sure, I can dress the meta frame into whatever the previous MAC-trapped frame was (PTP or not) and then I'll have .port_rxtstamp function see a 1-to-1 correspondence with meta frames in case everything works fine. But then I'll have non-PTP meta frames leaking up the stack... Regards, -Vladimir > Thanks, > Richard
