[PATCH] PCI: Make pcie_find_root_port() work for PCIe root ports as well

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Commit 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and
pci_find_pcie_root_port()") unified the root port finding functionality
into a single function but missed the fact that the passed in device may
already be a root port. This causes the kernel to block power management
of PCIe hierarchies in recent systems because ->bridge_d3 started to
return false for such ports after the commit in question.

Fixes: 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and pci_find_pcie_root_port()")
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: stable@vger.kernel.org
---
 include/linux/pci.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index c79d83304e52..c17c24f5eeed 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2169,8 +2169,13 @@ static inline int pci_pcie_type(const struct pci_dev *dev)
  */
 static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
 {
-	struct pci_dev *bridge = pci_upstream_bridge(dev);
+	struct pci_dev *bridge;
 
+	/* If dev is already root port */
+	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
+		return dev;
+
+	bridge = pci_upstream_bridge(dev);
 	while (bridge) {
 		if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
 			return bridge;
-- 
2.27.0