RE: [PATCH v7 3/9] software node: allow referencing firmware nodes

["Jiawen Wu" <jiawenwu@trustnetic.com>]

On Tue, Dec 23, 2025 4:09 PM, Bartosz Golaszewski wrote:
> On Tue, Dec 23, 2025 at 8:39 AM Jiawen Wu <jiawenwu@trustnetic.com> wrote:
> >
> > >
> > >  #define SOFTWARE_NODE_REFERENCE(_ref_, ...)                  \
> > >  (const struct software_node_ref_args) {                              \
> > > -     .node = _ref_,                                          \
> > > +     .swnode = _Generic(_ref_,                               \
> > > +                        const struct software_node *: _ref_, \
> > > +                        default: NULL),                      \
> > > +     .fwnode = _Generic(_ref_,                               \
> > > +                        struct fwnode_handle *: _ref_,       \
> > > +                        default: NULL),                      \
> > >       .nargs = COUNT_ARGS(__VA_ARGS__),                       \
> > >       .args = { __VA_ARGS__ },                                \
> > >  }
> >
> > This change seems incompatible with my driver txgbe, since the software nodes
> > are registered in " struct software_node * " but not " const struct software_node * ".
> >
> > So when I pulled the net-next-6.19-rc1 that merged this patch, to probe my driver.
> > The error logs shows:
> >
> > [    5.243396] txgbe 0000:10:00.0 (unnamed net_device) (uninitialized): unable to attach SFP bus: -EINVAL
> > [    5.243399] txgbe 0000:10:00.0: failed to init phylink
> > [    5.576008] txgbe 0000:10:00.0: probe with driver txgbe failed with error -22
> > [    6.109548] txgbe 0000:10:00.1 (unnamed net_device) (uninitialized): unable to attach SFP bus: -EINVAL
> > [    6.109551] txgbe 0000:10:00.1: failed to init phylink
> > [    6.442044] txgbe 0000:10:00.1: probe with driver txgbe failed with error -22
> >
> 
> This shouldn't have changed anything for existing software nodes - the
> pointer in struct software_node_ref_args has always been const. This
> would have failed at build-time if this was an issue. Have you
> bisected it to this very commit? What line is the -EINVAL assigned and
> for what reason?

The -EINVAL is assigned software_node_get_reference_args():

	if (ref->swnode)
		refnode = software_node_fwnode(ref->swnode);
	else if (ref->fwnode)
		refnode = ref->fwnode;
	else
		return -EINVAL;

I think the reason is that _Generic selection is restrictive, it only accept
exactly const struct software_node for software node references. So the
macro SOFTWARE_NODE_REFERENCE fall back to the default to set .swnode =  NULL.

And I temporarily added this line to fix it:

diff --git a/include/linux/property.h b/include/linux/property.h
index 272bfbdea7bf..e30ef23a9af3 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -371,6 +371,7 @@ struct software_node_ref_args {
 (const struct software_node_ref_args) {                                \
        .swnode = _Generic(_ref_,                               \
                           const struct software_node *: _ref_, \
+                          struct software_node *: _ref_,       \
                           default: NULL),                      \
        .fwnode = _Generic(_ref_,                               \
                           struct fwnode_handle *: _ref_,       \