diff options
Diffstat (limited to 'drivers/pci/probe.c')
| -rw-r--r-- | drivers/pci/probe.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 3761b1303529..070476036846 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2248,22 +2248,27 @@ static unsigned next_fn(struct pci_bus *bus, struct pci_dev *dev, unsigned fn) static int only_one_child(struct pci_bus *bus) { - struct pci_dev *parent = bus->self; + struct pci_dev *bridge = bus->self; - if (!parent || !pci_is_pcie(parent)) + /* + * Systems with unusual topologies set PCI_SCAN_ALL_PCIE_DEVS so + * we scan for all possible devices, not just Device 0. + */ + if (pci_has_flag(PCI_SCAN_ALL_PCIE_DEVS)) return 0; - if (pci_pcie_type(parent) == PCI_EXP_TYPE_ROOT_PORT) - return 1; /* - * PCIe downstream ports are bridges that normally lead to only a - * device 0, but if PCI_SCAN_ALL_PCIE_DEVS is set, scan all - * possible devices, not just device 0. See PCIe spec r3.0, - * sec 7.3.1. + * A PCIe Downstream Port normally leads to a Link with only Device + * 0 on it (PCIe spec r3.1, sec 7.3.1). As an optimization, scan + * only for Device 0 in that situation. + * + * Checking has_secondary_link is a hack to identify Downstream + * Ports because sometimes Switches are configured such that the + * PCIe Port Type labels are backwards. */ - if (parent->has_secondary_link && - !pci_has_flag(PCI_SCAN_ALL_PCIE_DEVS)) + if (bridge && pci_is_pcie(bridge) && bridge->has_secondary_link) return 1; + return 0; } |