RE: [PATCH 1/3] driver core: enable drivers to use deferred probe from init

Yuval Mintz
2014-07-28T18:30:32Z

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> On Mon, Jul 28, 2014 at 06:52:48PM +0200, Luis R. Rodriguez wrote:
> > On Mon, Jul 28, 2014 at 03:46:32PM +0000, Yuval Mintz wrote:
> > > Sorry for not being clear, but I didn't meant 'what guarantees that the device
> > > will be added to the deferred probe', but rather what guarantees that the
> > > deferred workqueue will be scheduled.
> > >
> > > To the best of my knowledge the deferring mechanism works only if one device
> > > is dependent upon another, e.g., for Multi-function devices where one device
> > > probe is dependent upon the others - which are soon-to-be probed.
> >
> > The workqueue will be kicked when driver_deferred_probe_trigger() gets
> > poked, we do that in the late_initcall(deferred_probe_initcall), it
> > also gets flushed there with a flush_workqueue(deferred_wq).

> But come to think of it that will work well for devices already plugged in
> so indeed I think that driver_deferred_probe_add() needs a check added
> for for if (!driver_deferred_probe_enable) then we have to
> driver_deferred_probe_trigger(). The driver_deferred_probe_enable is set
> to false upon init, but later on late init it gets set to true so with
> that check we'd only generate the trigger after late init call.

> I can fold that in the v2.

> Luis

But what about modules being added after the init-calls? If they try try to use this
mechanism, what guarantees they'll eventually get probed?

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