PCI/pwrctrl: Ensure that remote endpoint node parent has supply requirement

If OF graph is used in the PCI device node, the pwrctrl core creates a
pwrctrl device even if the remote endpoint doesn't have power supply
requirements. Since the device doesn't have any power supply requirements,
there was no pwrctrl driver to probe, leading to PCI controller driver
probe deferral as it waits for all pwrctrl drivers to probe before starting
bus scan.

This issue happens with Qcom ath12k devices with WSI interface attached to
the Qcom IPQ platforms.

Fix this issue by checking for the existence of at least one power supply
property in the remote endpoint parent node. To consolidate all the checks,
create a new helper pci_pwrctrl_is_required() and move all the checks
there.

Fixes: 9db8262 ("PCI/pwrctrl: Create pwrctrl device if graph port is found")
Reported-by: Raj Kumar Bhagat <raj.bhagat@oss.qualcomm.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Raj Kumar Bhagat <raj.bhagat@oss.qualcomm.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260223-pwrctrl-fixes-7-0-v2-1-97566dfb1809@oss.qualcomm.com

Author: Mani-Sadhasivam

drivers/pci/pwrctrl/core.c

@@ -268,6 +268,39 @@ int pci_pwrctrl_power_on_devices(struct device *parent)
 }
 EXPORT_SYMBOL_GPL(pci_pwrctrl_power_on_devices);
 
+/*
+ * Check whether the pwrctrl device really needs to be created or not. The
+ * pwrctrl device will only be created if the node satisfies below requirements:
+ *
+ * 1. Presence of compatible property to match against the pwrctrl driver (AND)
+ * 2. At least one of the power supplies defined in the devicetree node of the
+ *    device (OR) in the remote endpoint parent node to indicate pwrctrl
+ *    requirement.
+ */
+static bool pci_pwrctrl_is_required(struct device_node *np)
+{
+	struct device_node *endpoint;
+
+	if (!of_property_present(np, "compatible"))
+		return false;
+
+	if (of_pci_supply_present(np))
+		return true;
+
+	if (of_graph_is_present(np)) {
+		for_each_endpoint_of_node(np, endpoint) {
+			struct device_node *remote __free(device_node) =
+				of_graph_get_remote_port_parent(endpoint);
+			if (remote) {
+				if (of_pci_supply_present(remote))
+					return true;
+			}
+		}
+	}
+
+	return false;
+}
+
 static int pci_pwrctrl_create_device(struct device_node *np,
 				     struct device *parent)
 {
@@ -287,19 +320,7 @@ static int pci_pwrctrl_create_device(struct device_node *np,
 		return 0;
 	}
 
-	/*
-	 * Sanity check to make sure that the node has the compatible property
-	 * to allow driver binding.
-	 */
-	if (!of_property_present(np, "compatible"))
-		return 0;
-
-	/*
-	 * Check whether the pwrctrl device really needs to be created or not.
-	 * This is decided based on at least one of the power supplies defined
-	 * in the devicetree node of the device or the graph property.
-	 */
-	if (!of_pci_supply_present(np) && !of_graph_is_present(np)) {
+	if (!pci_pwrctrl_is_required(np)) {
 		dev_dbg(parent, "Skipping OF node: %s\n", np->name);
 		return 0;
 	}