Re: [RFC/PATCH 2/5] device property: introduce notion of subnodes for legacy boards

From: Dmitry Torokhov
Date: Fri Sep 21 2018 - 19:33:43 EST


On Thu, Sep 20, 2018 at 01:16:48PM +0300, Heikki Krogerus wrote:
> On Wed, Sep 19, 2018 at 10:13:26AM -0700, Dmitry Torokhov wrote:
> > > > diff --git a/drivers/base/pset_property.c b/drivers/base/pset_property.c
> > > > index 08ecc13080ae..63f2377aefe8 100644
> > > > --- a/drivers/base/pset_property.c
> > > > +++ b/drivers/base/pset_property.c
> > > > @@ -18,6 +18,11 @@ struct property_set {
> > > > struct device *dev;
> > > > struct fwnode_handle fwnode;
> > > > const struct property_entry *properties;
> > > > +
> > > > + struct property_set *parent;
> > > > + /* Entry in parent->children list */
> > > > + struct list_head child_node;
> > > > + struct list_head children;
> > >
> > > Add
> > >
> > > const char *name;
> > >
> > > and you can implement also pset_get_named_child_node().
> >
> > Or
> > char name[];
> >
> > to avoid separate allocation.
>
> Let's not do that, especially if you are planning on exporting this
> structure.

Can you please elaborate why? Not using pointer saves us 4/8 bytes +
however much memory we need for bookkeeping for the extra chunk. Given
that majority of pset nodes are unnamed this seems wasteful.

> If the name is coming from .rodata, there is no need to
> allocate anything for the name. Check kstrdup_const().

The data is most likely coming as __initconst so we do need to copy it.

>
> > Alternatively, we can add it later when we need it, and add
> > device_add_named_child_properties().
> >
> > I'll leave it up to Rafael to decide.
>
> Fair enough.
>
>
> Thanks,
>
> --
> heikki

Thanks.

--
Dmitry