pci_upstream_bridge
while ((parent = pci_upstream_bridge(parent))) {
parent = pci_upstream_bridge(parent);
while ((parent = pci_upstream_bridge(parent))) {
swds = pci_upstream_bridge(adev->pdev);
swus = pci_upstream_bridge(swds);
pdev = pci_upstream_bridge(adev->pdev);
ds_pdev = pci_upstream_bridge(adev->pdev);
us_pdev = pci_upstream_bridge(ds_pdev);