On Wed, Jan 13, 2021 at 05:58:12PM +0200, Andy Shevchenko wrote: > On Wed, Jan 13, 2021 at 05:55:04PM +0200, Andy Shevchenko wrote: > > On Wed, Jan 13, 2021 at 12:40:03AM +0000, Daniel Scally wrote: > > > On 11/01/2021 14:10, Heikki Krogerus wrote: > > > > ... > > > > > > +/** > > > > + * device_remove_software_node - Remove device's software node > > > > + * @dev: The device with the software node. > > > > + * > > > > + * This function will unregister the software node of @dev. > > > > + */ > > > > +void device_remove_software_node(struct device *dev) > > > > +{ > > > > + struct swnode *swnode; > > > > + > > > > + swnode = dev_to_swnode(dev); > > > > + if (!swnode) > > > > + return; > > > > + > > > > + kobject_put(&swnode->kobj); > > > > +} > > > > +EXPORT_SYMBOL_GPL(device_remove_software_node); > > > > > > I wonder if this also ought to set dev_fwnode(dev)->secondary back to > > > ERR_PTR(-ENODEV)? > > > > Looking more into this code I think we need to call > > > > set_secondary_fwnode(dev, NULL); > > > > among these lines. > > > > The real problem is that set_primary_fwnode() and set_secondary_fwnode() have > > no reference counting. If we have a chain ->primary->secondary->-ENODEV is > > being used somewhere we can't tell from here. > > > > So, in practice it means that we lack of some kind of primary node to increment > > reference count of the secondary node when the latter is chained to the given > > primary. But it makes things too complicated. Any other options for shared > > primary-secondary chain? Standalone primary along with standalone (exclusive) > > secondary doesn't need this AFAICS. Perhaps a flag to primary like shared / > > exclusive that will prevent breaking the chain in set_secondary_fwnode()? > > Or maybe I imagined only theoretical cases and we have no such issue? I think we should really start looking into the possibility of removing the whole secondary coupling, because that is the thing that is crippling us. Br, -- heikki