PCI_ACS_CTRL
pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
pci_read_config_word(dev, pos + PCI_ACS_CTRL, &caps.ctrl);
pci_write_config_word(dev, pos + PCI_ACS_CTRL, caps.ctrl);
pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
pci_read_config_word(pdev, pdev->acs_cap + PCI_ACS_CTRL, &val);