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.
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
>
>
