On Wed, 2019-06-26 at 08:36 -0500, Alex Elder wrote: > > We need to identify the existence of a WWAN device (which is I > guess--typically? always?--a modem). Perhaps that can be > discovered in some cases but I think it means a node described > by Device Tree. Yeah, perhaps that's something you could do. I'm not sure though. For one, for USB devices, obviously it isn't :-) And even for IPA you might want to support existing DTs I guess. > So you're saying you have a single Ethernet driver, and it can > drive an Ethernet device connected to a WWAN, or not connected > to a WWAN, without any changes. The only distinction is that > if the device is part of a WWAN it needs to register with the > WWAN framework. Is that right? That's what I'm thinking, and I believe (mostly from discussions with Dan) that this actually exists. > > > So maybe: > > > - Hardware probe detects a WWAN device > > > - The drivers that detect the WWAN device register it with the > > > WWAN core code. > > > - A control channel is instantiated at/before the time the WWAN > > > device is registered > > > - Something in user space should manage the bring-up of any > > > other things on the WWAN device thereafter > > > > But those things need to actually get connected first :-) > > What I meant is that the registering with the "WWAN core code" > is what does that "connecting." The WWAN code has the information > about what got registered. But as I said above, this WWAN device > needs to be identified, and I think (at least for IPA) that will > require something in Device Tree. That will "connect" them. > > Or I might be misunderstanding your point. No, I think we're mostly agreeing, just thinking about different scenarios. I think for IPA you don't really *need* anything in the DT though - as soon as the IPA driver is loaded you know for sure you actually have a modem there, and the IPA driver presumably loads based on some existing probing (didn't look at it now). Now, I don't know how the QMI channel to the modem is set up, so of course you'd want a way of identifying that the two channels (IPA and QMI) go to the same device and link them together in the WWAN framework. > > If userspace actually had the ability to create (data) channels, then it > > would have the ability to also remove them. Right now, this may or may > > not be supported by the drivers that act together to form the interfaces > > to a WWAN device. > > I think this (user space control) needs to be an option, but > it doesn't have to be the only way. Agree. johannes
