On Tue, Feb 09, 2021 at 11:04:08AM -0600, George McCollister wrote: > > >> In the DSA layer (dsa_slave_changeupper), could we merge the two HSR > > >> join/leave calls somehow? My guess is all drivers are going to end up > > >> having to do the same dance of deferring configuration until both ports > > >> are known. > > > > > > Describe what you mean a bit more. Do you mean join and leave should > > > each only be called once with both hsr ports being passed in? > > > > Exactly. Maybe we could use `netdev_for_each_lower_dev` to figure out if > > the other port has already been switched over to the new upper or > > something. I find it hard to believe that there is any hardware out > > there that can do something useful with a single HSR/PRP port anyway. > > If one port failed maybe it would still be useful to join one port if > the switch supported it? Maybe this couldn't ever happen anyway due > the way hsr is designed. > > How were you thinking this would work? Would it just not use > dsa_port_notify() and call a switch op directly after the second > port's dsa_slave_changeupper() call? Or would we instead keep port > notifiers and calls to dsa_switch_hsr_join for each port and just make > dsa_switch_hsr_join() not call the switch op to create the HSR until > the second port called it? I'm not all that familiar with how these > dsa notifiers work and would prefer to stick with using a similar > mechanism to the bridge and lag support. It would be nice to get some > feedback from the DSA maintainers on how they would prefer it to work > if they indeed had a preference at all.
Even though I understand where this is coming from, I have grown to dislike overengineered solutions. DSA is there to standardize how an Ethernet-connected switch interacts with the network stack, not to be the middle man that tries to offer a lending hand everywhere. If there is a 50/50 chance that this extra logic in the DSA mid layer will not be needed for the second switch that offloads HSR/PRP, then I'd go with "don't do it". Just emit a hsr_join for both ports and let the driver deal with it.
