Hi Alex, all, > > Exactly correct. This is what Johannes is discussing in his "cellular > > modem APIs - take 2" thread about how this should all be organized at > > the driver level and I think we should figure that out before we commit > > to IPA-with-a-useless-netdev that requires rmnets to be created on top. > > That may end up being the solution but let's have that discussion. > > I looked at Johannes' message and the follow-on discussion. Thanks :-) Sorry also, Dan had pointed me to this thread and the discussion, but I was travelling last week and not very reachable. > As I've > made clear before, my work on this has been focused on the IPA transport, > and some of this higher-level LTE architecture is new to me. But it > seems pretty clear that an abstracted WWAN subsystem is a good plan, > because these devices represent a superset of what a "normal" netdev > implements. I'm not sure I'd actually call it a superset. By themselves, these netdevs are actually completely useless to the network stack, AFAICT. Therefore, the overlap with netdevs you can really use with the network stack is pretty small? > HOWEVER I disagree with your suggestion that the IPA code should > not be committed until after that is all sorted out. In part it's > for selfish reasons, but I think there are legitimate reasons to > commit IPA now *knowing* that it will need to be adapted to fit > into the generic model that gets defined and developed. Here > are some reasons why. I can't really argue with those, though I would point out that the converse also holds - if we commit to this now, then we will have to actually keep the API offered by IPA/rmnet today, so we cannot actually remove the netdev again, even if we do migrate it to offer support for a WWAN framework in the future. > Second, the IPA code has been out for review recently, and has been > the subject of some detailed discussion in the past few weeks. Arnd > especially has invested considerable time in review and discussion. > Delaying things until after a better generic model is settled on > (which I'm guessing might be on the order of months) I dunno if it really has to be months. I think we can cobble something together relatively quickly that addresses the needs of IPA more specifically, and then extend later? But OTOH it may make sense to take a more paced approach and think about the details more carefully than we have over in the other thread so far. > Third, having the code upstream actually means the actual requirements > for rmnet-over-IPA are clear and explicit. This might not be a huge > deal, but I think it's better to devise a generic WWAN scheme that > can refer to actual code than to do so with assumptions about what > will work with rmnet (and others). As far as I know, the upstream > rmnet has no other upstream back end; IPA will make it "real." Is that really true? I had previously been told that rmnet actually does have use with a few existing drivers. If true though, then I think this would be the killer argument *in favour* of *not* merging this - because that would mean we *don't* have to actually keep the rmnet API around for all foreseeable future. > I support the idea of developing a generic WWAN framework, and I > can assure you I'll be involved enough to perhaps be one of the > first to implement a new generic scheme. Thanks! johannes
