[PATCH v2 2/4] gpio: swnode: defer probe on references to unregistered software nodes

[Bartosz Golaszewski]

fwnode_property_get_reference_args() now returns -ENXIO when called on a
software node referencing another software node which has not yet been
registered as a firmware node. It makes sense to defer probe in this
situation as the node will most likely be registered later on and we'll
be able to resolve the reference eventually. Change the behavior of
swnode_find_gpio() to return -EPROBE_DEFER if the software node reference
resolution returns -ENXIO.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
 drivers/gpio/gpiolib-swnode.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-swnode.c
index 0d7f3f09a0b4bee0cf1bbdaa8b7b8ae4cd5de581..06d74e9e199de0b91a019e5e15d4b83d330291e7 100644
--- a/drivers/gpio/gpiolib-swnode.c
+++ b/drivers/gpio/gpiolib-swnode.c
@@ -95,6 +95,15 @@ struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
 			break;
 	}
 	if (ret) {
+		if (ret == -ENXIO)
+			/*
+			 * -ENXIO for a software node reference lookup means
+			 *  that a remote struct software_node exists but has
+			 *  not yet been registered as a firmware node. Defer
+			 *  until this happens.
+			 */
+			return ERR_PTR(-EPROBE_DEFER);
+
 		pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
 			__func__, propname, fwnode, idx);
 		return ERR_PTR(ret);

-- 
2.47.3