pci_real_dma_dev
pdev = pci_real_dma_dev(to_pci_dev(dev));
pci_real_dma_dev(to_pci_dev(dev)) != to_pci_dev(dev);
pci_real_dma_dev(msi_desc_to_pci_dev(info->desc)));
pci_real_dma_dev(dev1) == dev2 ||
pci_real_dma_dev(dev2) == dev1;
pdev = pci_real_dma_dev(pdev);
struct pci_dev *pci_real_dma_dev(struct pci_dev *dev);