Re: [PATCH v2 09/11] of: property: Simplify of_link_to_phandle()

Sakari Ailus
2023-01-30T18:16:04Z

Hi Saravana,

On Thu, Jan 26, 2023 at 04:11:36PM -0800, Saravana Kannan wrote:
> The driver core now:
> - Has the parent device of a supplier pick up the consumers if the
> supplier never has a device created for it.
> - Ignores a supplier if the supplier has no parent device and will never
> be probed by a driver
>
> And already prevents creating a device link with the consumer as a
> supplier of a parent.
>
> So, we no longer need to find the "compatible" node of the supplier or
> do any other checks in of_link_to_phandle(). We simply need to make sure
> that the supplier is available in DT.
>
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
> drivers/of/property.c | 84 +++++++------------------------------------
> 1 file changed, 13 insertions(+), 71 deletions(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 134cfc980b70..c651aad6f34b 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1062,20 +1062,6 @@ of_fwnode_device_get_match_data(const struct fwnode_handle *fwnode,
> return of_device_get_match_data(dev);
> }
>
> -static bool of_is_ancestor_of(struct device_node *test_ancestor,
> - struct device_node *child)
> -{
> - of_node_get(child);
> - while (child) {
> - if (child == test_ancestor) {
> - of_node_put(child);
> - return true;
> - }
> - child = of_get_next_parent(child);
> - }
> - return false;
> -}
> -
> static struct device_node *of_get_compat_node(struct device_node *np)
> {
> of_node_get(np);
> @@ -1106,71 +1092,27 @@ static struct device_node *of_get_compat_node_parent(struct device_node *np)
> return node;
> }
>
> -/**
> - * of_link_to_phandle - Add fwnode link to supplier from supplier phandle
> - * @con_np: consumer device tree node
> - * @sup_np: supplier device tree node
> - *
> - * Given a phandle to a supplier device tree node (@sup_np), this function
> - * finds the device that owns the supplier device tree node and creates a
> - * device link from @dev consumer device to the supplier device. This function
> - * doesn't create device links for invalid scenarios such as trying to create a
> - * link with a parent device as the consumer of its child device. In such
> - * cases, it returns an error.
> - *
> - * Returns:
> - * - 0 if fwnode link successfully created to supplier
> - * - -EINVAL if the supplier link is invalid and should not be created
> - * - -ENODEV if struct device will never be create for supplier
> - */
> -static int of_link_to_phandle(struct device_node *con_np,
> +static void of_link_to_phandle(struct device_node *con_np,
> struct device_node *sup_np)
> {
> - struct device *sup_dev;
> - struct device_node *tmp_np = sup_np;
> + struct device_node *tmp_np = of_node_get(sup_np);
>
> - /*
> - * Find the device node that contains the supplier phandle. It may be
> - * @sup_np or it may be an ancestor of @sup_np.
> - */
> - sup_np = of_get_compat_node(sup_np);
> - if (!sup_np) {
> - pr_debug("Not linking %pOFP to %pOFP - No device\n",
> - con_np, tmp_np);
> - return -ENODEV;
> - }
> + /* Check that sup_np and its ancestors are available. */
> + while (tmp_np) {
> + if (of_fwnode_handle(tmp_np)->dev) {
> + of_node_put(tmp_np);
> + break;
> + }
>
> - /*
> - * Don't allow linking a device node as a consumer of one of its
> - * descendant nodes. By definition, a child node can't be a functional
> - * dependency for the parent node.
> - */
> - if (of_is_ancestor_of(con_np, sup_np)) {
> - pr_debug("Not linking %pOFP to %pOFP - is descendant\n",
> - con_np, sup_np);
> - of_node_put(sup_np);
> - return -EINVAL;
> - }
> + if (!of_device_is_available(tmp_np)) {
> + of_node_put(tmp_np);
> + return;
> + }
>
> - /*
> - * Don't create links to "early devices" that won't have struct devices
> - * created for them.
> - */
> - sup_dev = get_dev_from_fwnode(&sup_np->fwnode);
> - if (!sup_dev &&
> - (of_node_check_flag(sup_np, OF_POPULATED) ||
> - sup_np->fwnode.flags & FWNODE_FLAG_NOT_DEVICE)) {
> - pr_debug("Not linking %pOFP to %pOFP - No struct device\n",
> - con_np, sup_np);
> - of_node_put(sup_np);
> - return -ENODEV;
> + tmp_np = of_get_next_parent(tmp_np);
> }
> - put_device(sup_dev);
>
> fwnode_link_add(of_fwnode_handle(con_np), of_fwnode_handle(sup_np));

fwnode_link_add() returns int. Why is the return type of this function
changed to void?

> - of_node_put(sup_np);
> -
> - return 0;
> }
>
> /**

--
Regards,

Sakari Ailus