From: Ashok Raj ashok.raj@intel.com
commit aa0ce96d72dd2e1b0dfd0fb868f82876e7790878 upstream.
Root Complex Integrated Endpoints (RCiEPs) do not have an upstream bridge, so pci_configure_mps() previously ignored them, which may result in reduced performance.
Instead, program the Max_Payload_Size of RCiEPs to the maximum supported value (unless it is limited for the PCIE_BUS_PEER2PEER case). This also affects the subsequent programming of Max_Read_Request_Size because Linux programs MRRS based on the MPS value.
Fixes: 9dae3a97297f ("PCI: Move MPS configuration check to pci_configure_device()") Link: https://lore.kernel.org/r/1585343775-4019-1-git-send-email-ashok.raj@intel.c... Tested-by: Dave Jiang dave.jiang@intel.com Signed-off-by: Ashok Raj ashok.raj@intel.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/pci/probe.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)
--- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1557,13 +1557,33 @@ static void pci_configure_mps(struct pci struct pci_dev *bridge = pci_upstream_bridge(dev); int mps, p_mps, rc;
- if (!pci_is_pcie(dev) || !bridge || !pci_is_pcie(bridge)) + if (!pci_is_pcie(dev)) return;
/* MPS and MRRS fields are of type 'RsvdP' for VFs, short-circuit out */ if (dev->is_virtfn) return;
+ /* + * For Root Complex Integrated Endpoints, program the maximum + * supported value unless limited by the PCIE_BUS_PEER2PEER case. + */ + if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) { + if (pcie_bus_config == PCIE_BUS_PEER2PEER) + mps = 128; + else + mps = 128 << dev->pcie_mpss; + rc = pcie_set_mps(dev, mps); + if (rc) { + pci_warn(dev, "can't set Max Payload Size to %d; if necessary, use "pci=pcie_bus_safe" and report a bug\n", + mps); + } + return; + } + + if (!bridge || !pci_is_pcie(bridge)) + return; + mps = pcie_get_mps(dev); p_mps = pcie_get_mps(bridge);