PCI: Allow PCI express root ports to find themselves

If the pci_find_pcie_root_port() function is called on a root port
itself, return the root port rather than NULL.

This effectively reverts commit 0e405232871d6 ("PCI: fix oops when
try to find Root Port for a PCI device") which added an extra check
that would now be redundant.

Fixes: a99b646afa8a ("PCI: Disable PCIe Relaxed Ordering if unsupported")
Fixes: c56d4450eb68 ("PCI: Turn off Request Attributes to avoid Chelsio T5 Completion erratum")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 5 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index da5570cf5c6a..fdf65a6c13f6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -514,7 +514,7 @@ EXPORT_SYMBOL(pci_find_resource);
  */
 struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
 {
-        struct pci_dev *bridge, *highest_pcie_bridge = NULL;
+        struct pci_dev *bridge, *highest_pcie_bridge = dev;
 
         bridge = pci_upstream_bridge(dev);
         while (bridge && pci_is_pcie(bridge)) {
@@ -522,11 +522,10 @@ struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
                 bridge = pci_upstream_bridge(bridge);
         }
 
-        if (highest_pcie_bridge &&
-            pci_pcie_type(highest_pcie_bridge) == PCI_EXP_TYPE_ROOT_PORT)
-                return highest_pcie_bridge;
+        if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
+                return NULL;
 
-        return NULL;
+        return highest_pcie_bridge;
 }
 EXPORT_SYMBOL(pci_find_pcie_root_port);