Re: [PATCH v2 00/17] net: introduce Qualcomm IPA driver

[Arnd Bergmann]

On Tue, Jun 18, 2019 at 10:39 PM Johannes Berg
<johannes@xxxxxxxxxxxxxxxx> wrote:
> On Tue, 2019-06-18 at 22:33 +0200, Arnd Bergmann wrote:

> It seems to me though that this is far more complex than what I'm
> proposing? What I'm proposing there doesn't even need any userspace
> involvement, as long as all the pieces are in the different sub-drivers,
> they'd fall out automatically.
>
> And realistically, the wwan_device falls out anyway at some point, the
> only question is if we really make one specific driver be the "owner" of
> it. I'm suggesting that we don't, and just make its lifetime depend on
> the links to parts it has (unless something like IPA actually wants to
> be an owner).

My feeling so far is that having the wwan_device be owned by a device
gives a nicer abstraction model that is also simpler for the common
case. A device driver like ipa would end up with a probe() function
that does does wwan_device_alloc/wwan_device_register, corresponding
to alloc_etherdev/register_netdev, and then communicates through
callbacks.

I agree the compound device case would get more complex by
shoehorning it into this model, but that can be a valid tradeoff
if it's the exceptional case rather than the common one.

      Arnd