Hi Heikki,
On Thu, Sep 20, 2018 at 04:53:48PM +0300, Heikki Krogerus wrote:
> Hi Dmitry,
>
> On Mon, Sep 17, 2018 at 11:16:00AM -0700, Dmitry Torokhov wrote:
> > +/**
> > + * device_add_child_properties - Add a collection of properties to a
> > device object.
> > + * @dev: Device to add properties to.
>
> In case you didn't notice my comment for this, you are missing @parent
> here.
>
> But why do you need both the parent and the dev?
I could go by parent only and fetch dev from parent.
>
> > + * @properties: Collection of properties to add.
> > + *
> > + * Associate a collection of device properties represented by @properties
> > as a
> > + * child of given @parent firmware node. The function takes a copy of
> > + * @properties.
> > + */
> > +struct fwnode_handle *
> > +device_add_child_properties(struct device *dev,
> > + struct fwnode_handle *parent,
> > + const struct property_entry *properties)
> > +{
> > + struct property_set *p;
> > + struct property_set *parent_pset;
> > +
> > + if (!properties)
> > + return ERR_PTR(-EINVAL);
> > +
> > + parent_pset = to_pset_node(parent);
>
> For this function, the parent will in practice have to be
> dev_fwnode(dev), so I don't think you need @parent at all, no?
>
> There is something wrong here..
Yes, I expect majority of the calls will use dev_fwnode(dev) as parent,
but nobody stops you from doing:
device_add_properties(dev, props);
c1 = device_add_child_properties(dev, dev_fwnode(dev), cp1);
c2 = device_add_child_properties(dev, c1, cp2);
c3 = device_add_child_properties(dev, c2, cp3);
...
>
> > + if (!parent_pset)
> > + return ERR_PTR(-EINVAL);
> > +
> > + p = pset_create_set(properties);
> > + if (IS_ERR(p))
> > + return ERR_CAST(p);
> > +
> > + p->dev = dev;
>
> That looks wrong.
>
> I'm guessing the assumption here is that the child nodes will never be
> assigned to their own devices, but you can't do that. It will limit
> the use of the child nodes to a very small number of cases, possibly
> only to gpios.
If I need to assign a node to a device I'll use device_add_properties()
API. device_add_child_properties() is for nodes living "below" the
device.
All nodes (the primary/secondary and children) would point to the owning
device, just for convenience.
>
> I think that has to be fixed. It should not be a big deal. Just expect
> the child nodes to be removed separately, and add ref counting to the
> struct property_set handling.
Why do we need to remove them separately and what do we need refcounting
for?
>
> > + p->parent = parent_pset;
> > + list_add_tail(&p->child_node, &parent_pset->children);
> > +
> > + return &p->fwnode;
> > +}
> > +EXPORT_SYMBOL_GPL(device_add_child_properties);
>
> The child nodes will change the purpose of the build-in property
> support. Originally the goal was just to support adding of build-in
> device properties to real firmware nodes, but things have changed
> quite a bit from that. These child nodes are purely tied to the
> build-in device property support, so we should be talking about adding
> pset type child nodes to pset type parent nodes in the API:
> fwnode_pset_add_child_node(), or something like that.
OK, I can change device_add_child_properties() to
fwnode_pset_add_child_node() if Rafael would prefer this name.
Thanks.
--
Dmitry
