diff options
Diffstat (limited to 'drivers/pci/p2pdma.c')
| -rw-r--r-- | drivers/pci/p2pdma.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 30b1df3c9d2f..462b429ad243 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -326,15 +326,16 @@ static const struct pci_p2pdma_whitelist_entry { }; /* - * This lookup function tries to find the PCI device corresponding to a given - * host bridge. + * If the first device on host's root bus is either devfn 00.0 or a PCIe + * Root Port, return it. Otherwise return NULL. * - * It assumes the host bridge device is the first PCI device in the - * bus->devices list and that the devfn is 00.0. These assumptions should hold - * for all the devices in the whitelist above. + * We often use a devfn 00.0 "host bridge" in the pci_p2pdma_whitelist[] + * (though there is no PCI/PCIe requirement for such a device). On some + * platforms, e.g., Intel Skylake, there is no such host bridge device, and + * pci_p2pdma_whitelist[] may contain a Root Port at any devfn. * - * This function is equivalent to pci_get_slot(host->bus, 0), however it does - * not take the pci_bus_sem lock seeing __host_bridge_whitelist() must not + * This function is similar to pci_get_slot(host->bus, 0), but it does + * not take the pci_bus_sem lock since __host_bridge_whitelist() must not * sleep. * * For this to be safe, the caller should hold a reference to a device on the @@ -350,10 +351,14 @@ static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host) if (!root) return NULL; - if (root->devfn != PCI_DEVFN(0, 0)) - return NULL; - return root; + if (root->devfn == PCI_DEVFN(0, 0)) + return root; + + if (pci_pcie_type(root) == PCI_EXP_TYPE_ROOT_PORT) + return root; + + return NULL; } static bool __host_bridge_whitelist(struct pci_host_bridge *host, |