[PATCH v22 08/13] mfd: core: Add firmware-node support to MFD cells

[Bartosz Golaszewski]

On Thu, May 21, 2026 at 6:27 PM Lee Jones <lee at kernel.org> wrote:
>
> On Thu, 21 May 2026, Bartosz Golaszewski wrote:
>
> > On Thu, May 21, 2026 at 3:24 PM Lee Jones <lee at kernel.org> wrote:
> > >
> > > >
> > > > I suggested it because of its flexibility. The alternative I had in
> > > > mind is something like a new field in mfd_cell:
> > > >
> > > >     const char *cell_node_name;
> > > >
> > > > Which - if set - would tell MFD to look up an fwnode that's a child of
> > > > the parent device's node by name - as it may not have a compatible.
> > >
> > > Remind me why the chlid device can't look-up its own fwnode?
> > >
> >
> > Oh sure it can, but should it? I'm not sure it's logically sound to
> > have the child device reach into the parent, look up the fwnode and
> > then assign it to itself after it's already attached to the driver.
> > This should be done at the subsystem level before the device is
> > registered.
>
> Leaf drivers reach back into the parent all the time.
>

But drivers don't generally assign firmware nodes to devices they are
already bound to. This is racy as in probe() the device is already
visible to the system. There's no synchronization of device property
access - properties are assumed to be read-only for a registered
device.

Bartosz