On 6/18/19 1:48 PM, Johannes Berg wrote: > Just to add to Dan's response, I think he's captured our discussions and > thoughts well. > >> First, a few terms (correct or improve as you like): > > Thanks for defining, we don't do that nearly often enough. > >> - WWAN device is a hardware device (like IPA) that presents a >> connection between AP and modem, and presents an interface >> that allows the use of that connection to be managed. > > Yes. But I was actually thinking of a "wwan_dev" to be a separate > structure, not *directly* owned by a single driver and used to represent > the hardware like a (hypothetical) "struct ipa_dev". I think you're talking about creating a coordination interface that allows multiple drivers to interact with a WWAN device, which might implement several independent features. >> - WWAN netdevice represents a Linux network interface, with its >> operations and queues, etc., but implements a standardized >> set of WWAN-specific operations. It represents a logical >> ' channel whose data is multiplexed over the WWAN device. > > I'm not sure I'd asy it has much WWAN-specific operations? But yeah, I > guess it might. I want to withdraw this notion of a "WWAN netdevice"... >> - WWAN channel is a user space abstraction that corresponds >> with a WWAN netdevice (but I'm not clear on all the ways >> they differ or interact). > > As Dan said, this could be a different abstraction than a netdevice, > like a TTY, etc. Right, I get that now. . . . >> - Which WWAN channel attributes must be set *before* the >> channel is activated, and can't be changed? Are there any >> that can be changed dynamically? > > It's a good question. I threw a "u32 pdn" in there, but I'm not actually > sure that's what you *really* need? > > Maybe the modem and userspace just agree on some arbitrary "session > identifier"? Dan mentions "MUX ID" or "MBIM Session ID", maybe there > really is no good general term for this and we should just call it a > "session identifier" and agree that it depends on the control protocol > (MBIM vs. QMI vs. ...)? > >> And while the whole point of this is to make things generic, >> it might be nice to have a way to implement a new feature >> before it can be "standardized". > > Not sure I understand this? I'm talking about a way to experiment with new functionality in a way that's explicitly not part of the interface. But doing that isn't necessary and it's probably not a good idea anyway. > FWIW, I actually came to this because we want to upstream a driver for > an Intel modem, but ... can't really make up our mind on whether or not > to use VLAN tags, something like rmnet (but we obviously cannot use > rmnet, so that'd be another vendor specific interface like rmnet), or > sysfs, or any of the other methods we have today ... :-) OK cool then we have some common needs. Let's get this defined so we can use it for both! -Alex > > johannes >
