[PATCH] PCI: of: Skip dynamic nodes for bridges without a subordinate bus

[Angel J <iamanaws@httpd.dev>]

A device can satisfy pci_is_bridge() without having a subordinate bus.
The dynamic OF helpers for bus-range and interrupt-map dereference
pdev->subordinate without checking it.

On a Dell XPS 8940, device 0000:00:00.0 [8086:4c43] has no subordinate
bus, and enabling CONFIG_PCI_DYNAMIC_OF_NODES causes an early boot hang.

Skip dynamic OF node creation for bridges without a subordinate bus.
This allows the machine to boot while preserving node creation for the
other bridges.

Fixes: 407d1a51921e ("PCI: Create device tree node for bridge")
Cc: stable@vger.kernel.org
Signed-off-by: Angel J <iamanaws@httpd.dev>
---
 drivers/pci/of.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index a51dff91b..971c79c2a 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -765,6 +765,10 @@ void of_pci_make_dev_node(struct pci_dev *pdev)
 	if (!ppnode)
 		return;
 
+	/* Bridge properties require a subordinate bus. */
+	if (pci_is_bridge(pdev) && !pdev->subordinate)
+		return;
+
 	if (pci_is_bridge(pdev))
 		pci_type = "pci";
 	else
-- 
2.54.0