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>

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);