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| author | Ashok Raj <ashok.raj@intel.com> | 2020-03-27 14:16:15 -0700 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2020-05-14 18:26:53 -0500 |
| commit | aa0ce96d72dd2e1b0dfd0fb868f82876e7790878 (patch) | |
| tree | a405e395550788b5e68f4eb3b6f851b7ac76ae9f /drivers/pci/probe.c | |
| parent | 9885440b16b8fc1dd7275800fd28f56a92f60896 (diff) | |
| download | lwn-aa0ce96d72dd2e1b0dfd0fb868f82876e7790878.tar.gz lwn-aa0ce96d72dd2e1b0dfd0fb868f82876e7790878.zip | |
PCI: Program MPS for RCiEP devices
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.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
Diffstat (limited to 'drivers/pci/probe.c')
| -rw-r--r-- | drivers/pci/probe.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index e064ded6fbec..27c43ff63cd5 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -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); |