Re: [PATCH v2 1/4] software node: return -ENXIO when referenced swnode is not registered yet

[Bartosz Golaszewski]

On Thu, Apr 2, 2026 at 10:43 PM Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
>
> On Thu, Apr 02, 2026 at 04:35:34PM +0300, Andy Shevchenko wrote:
> > On Thu, Apr 02, 2026 at 02:54:26PM +0200, Bartosz Golaszewski wrote:
> > > It's possible that at the time of resolving a reference to a remote
> > > software node, the node we know exists is not yet registered as a full
> > > firmware node. We currently return -ENOENT in this case but the same
> > > error code is also returned in some other cases, like the reference
> > > property with given name not existing in the property list of the local
> > > software node.
> > >
> > > It makes sense to let users know that we're dealing with an unregistered
> > > software node so that they can defer probe - the situation is somewhat
> > > similar to there existing a firmware node to which no device is bound
> > > yet - which is valid grounds for probe deferral. To that end: use -ENXIO
> > > which stands for "No such device or address".
> >
> > This error code is also too generic to my taste. What about alternative(s)?
> > EADDRNOTAVAIL
> > ENOTCONN
> >
> > (The brief grep shows that the second one might suit slightly better than the
> >  first one by existing use cases.)
>
> We are in the core of the driver core. Why not simply use -EPROBE_DEFER
> to which all users will resolve this error to and call it a day?
>

Because -EPROBE_DEFER only makes sense in probe() context, while
fwnode_get_reference_args() may be called in many other situations. I
think ENOTCONN as "not connected" makes sense, though the string
representation says: "Transport endpoint is not connected" which
doesn't spell out quite the same thing.

Bart