PCI: Program MPS for RCiEP devices (aa0ce96d) · Commits · 戴 / test

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: ("PCI: Move MPS configuration check to pci_configure_device()") Link: https://lore.kernel.org/r/1585343775-4019-1-git-send-email-ashok.raj@intel.com 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

drivers/pci/probe.c

+21 −1

Original line number	Diff line number	Diff line
		@@ -1937,13 +1937,33 @@ static void pci_configure_mps(struct pci_dev *dev)
		struct pci_dev *bridge = pci_upstream_bridge(dev);
		int mps, mpss, 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);

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