diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 8cf573fca307..7d4f0db5ac26 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2381,6 +2381,37 @@ static void pci_configure_serr(struct pci_dev *dev) } } +static void pci_configure_rcb(struct pci_dev *dev) +{ + struct pci_dev *rp; + u16 rp_lnkctl; + + /* + * Per PCIe r7.0, sec 7.5.3.7, RCB is only meaningful in Root Ports + * (where it is read-only), Endpoints, and Bridges. It may only be + * set for Endpoints and Bridges if it is set in the Root Port. For + * Endpoints, it is 'RsvdP' for Virtual Functions. + */ + if (!pci_is_pcie(dev) || + pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT || + pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM || + pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM || + pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC || + dev->is_virtfn) + return; + + /* Root Port often not visible to virtualized guests */ + rp = pcie_find_root_port(dev); + if (!rp) + return; + + pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &rp_lnkctl); + pcie_capability_clear_and_set_word(dev, PCI_EXP_LNKCTL, + PCI_EXP_LNKCTL_RCB, + (rp_lnkctl & PCI_EXP_LNKCTL_RCB) ? + PCI_EXP_LNKCTL_RCB : 0); +} + static void pci_configure_device(struct pci_dev *dev) { pci_configure_mps(dev); @@ -2390,6 +2421,7 @@ static void pci_configure_device(struct pci_dev *dev) pci_configure_aspm_l1ss(dev); pci_configure_eetlp_prefix(dev); pci_configure_serr(dev); + pci_configure_rcb(dev); pci_acpi_program_hp_params(dev); }