Le Tue, 3 May 2022 08:45:11 -0500,
Rob Herring <robh@xxxxxxxxxx> a écrit :
> On Wed, Apr 27, 2022 at 11:45:00AM +0200, Clément Léger wrote:
> > When enabling CONFIG_OF on a platform where of_root is not populated by
> > firmware, we end up without a root node. In order to apply overlays and
> > create subnodes of the root node, we need one. This commit creates an
> > empty root node if not present.
>
> The existing unittest essentially does the same thing for running the
> tests on non-DT systems. It should be modified to use this support
> instead. Maybe that's just removing the unittest code that set of_root.
Acked, I'll try the unit test on my system.
>
> I expect Frank will have some comments.
>
> > Co-developed-by: Rob Herring <robh@xxxxxxxxxx>
> > Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
> > Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
> > ---
> > drivers/of/base.c | 16 ++++++++++++++--
> > 1 file changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index e7d92b67cb8a..6b8584c39f73 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -177,6 +177,19 @@ void __init of_core_init(void)
> > pr_err("failed to register existing nodes\n");
> > return;
> > }
> > +
> > + if (!of_root) {
> > + of_root = kzalloc(sizeof(*of_root), GFP_KERNEL);
> > + if (!of_root) {
> > + mutex_unlock(&of_mutex);
> > + pr_err("failed to create root node\n");
> > + return;
> > + }
> > +
> > + of_root->full_name = "/";
> > + of_node_init(of_root);
> > + }
> > +
> > for_each_of_allnodes(np) {
> > __of_attach_node_sysfs(np);
> > if (np->phandle && !phandle_cache[of_phandle_cache_hash(np->phandle)])
> > @@ -185,8 +198,7 @@ void __init of_core_init(void)
> > mutex_unlock(&of_mutex);
> >
> > /* Symlink in /proc as required by userspace ABI */
> > - if (of_root)
> > - proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
> > + proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
> > }
> >
> > static struct property *__of_find_property(const struct device_node *np,
> > --
> > 2.34.1
> >
> >
--
Clément Léger,
Embedded Linux and Kernel engineer at Bootlin
https://bootlin.com
