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PCI: Program MPS for RCiEP devices

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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: 9dae3a9729 ("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
This commit is contained in:
Ashok Raj 2020-03-27 14:16:15 -07:00 committed by Bjorn Helgaas
parent 9885440b16
commit aa0ce96d72
1 changed files with 21 additions and 1 deletions
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22
drivers/pci/probe.c
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@ -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);