PCI: Preserve MPS and MRRS when applying _HPX settings

Linux manages MPS and MRRS settings to keep them consistent across the PCIe
fabric.  BIOS doesn't participate in this Linux management, so ignore that
part of any _HPX settings it supplies.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1ff2105ba401..cb411fbb6435 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1301,6 +1301,16 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
                 return;
         }
 
+        /*
+         * Don't allow _HPX to change MPS or MRRS settings.  We manage
+         * those to make sure they're consistent with the rest of the
+         * platform.
+         */
+        hpp->pci_exp_devctl_and |= PCI_EXP_DEVCTL_PAYLOAD |
+                                    PCI_EXP_DEVCTL_READRQ;
+        hpp->pci_exp_devctl_or &= ~(PCI_EXP_DEVCTL_PAYLOAD |
+                                    PCI_EXP_DEVCTL_READRQ);
+
         /* Initialize Device Control Register */
         pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
                         ~hpp->pci_exp_devctl_and, hpp->pci_exp_devctl_or);