[RFC PATCH v1 2/2] of: dynamic: Fix probing of overlay devices

[Saravana Kannan]

On Mon, Apr 8, 2024 at 4:13 PM Saravana Kannan <saravanak at google.com> wrote:
>
> Get fw_devlink to work well with overlay devices.
>
> Signed-off-by: Saravana Kannan <saravanak at google.com>
> ---
>  drivers/base/core.c    | 10 ++++++++++
>  drivers/of/dynamic.c   |  8 ++++++++
>  include/linux/fwnode.h |  2 ++
>  3 files changed, 20 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 5f4e03336e68..d856f9c5d601 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -237,6 +237,16 @@ static void __fw_devlink_pickup_dangling_consumers(struct fwnode_handle *fwnode,
>                 __fw_devlink_pickup_dangling_consumers(child, new_sup);
>  }
>
> +
> +void fw_devlink_pickup_dangling_consumers(struct fwnode_handle *child,
> +                                                struct fwnode_handle *parent)
> +{
> +       mutex_lock(&fwnode_link_lock);
> +       __fw_devlink_pickup_dangling_consumers(child, parent);
> +       __fw_devlink_link_to_consumers(parent->dev);
> +       mutex_unlock(&fwnode_link_lock);
> +}
> +
>  static DEFINE_MUTEX(device_links_lock);
>  DEFINE_STATIC_SRCU(device_links_srcu);
>
> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> index 19a1a38554f2..0a936f46820e 100644
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -237,6 +237,7 @@ static void __of_attach_node(struct device_node *np)
>  int of_attach_node(struct device_node *np)
>  {
>         struct of_reconfig_data rd;
> +       struct fwnode_handle *fwnode, *parent;
>
>         memset(&rd, 0, sizeof(rd));
>         rd.dn = np;
> @@ -246,6 +247,13 @@ int of_attach_node(struct device_node *np)
>         mutex_unlock(&of_mutex);
>
>         of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, &rd);
> +       fwnode = of_fwnode_handle(np);
> +       fwnode_for_each_parent_node(fwnode, parent)
> +               if (parent->dev) {
> +                       fw_devlink_pickup_dangling_consumers(fwnode, parent);
> +                       fwnode_handle_put(parent);
> +                       break;
> +               }

I'm clearly calling this in the wrong location. Please move this logic
to __of_changeset_entry_notify() and for the case
OF_RECONFIG_ATTACH_NODE. Haven't fully thought through the DETACH
case, but it should work correctly for that case too. If not, I'll
take care of that next.

-Saravana

>
>         return 0;
>  }
> diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
> index 0d79070c5a70..4b3f697a90e8 100644
> --- a/include/linux/fwnode.h
> +++ b/include/linux/fwnode.h
> @@ -220,6 +220,8 @@ int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup,
>                     u8 flags);
>  void fwnode_links_purge(struct fwnode_handle *fwnode);
>  void fw_devlink_purge_absent_suppliers(struct fwnode_handle *fwnode);
> +void fw_devlink_pickup_dangling_consumers(struct fwnode_handle *child,
> +                                         struct fwnode_handle *parent);
>  bool fw_devlink_is_strict(void);
>
>  #endif
> --
> 2.44.0.478.gd926399ef9-goog
>