diff options
Diffstat (limited to 'drivers/pci/probe.c')
| -rw-r--r-- | drivers/pci/probe.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 795c9026d55f..04e74f485714 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -856,6 +856,8 @@ void set_pcie_port_type(struct pci_dev *pdev) pdev->pcie_cap = pos; pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, ®16); pdev->pcie_type = (reg16 & PCI_EXP_FLAGS_TYPE) >> 4; + pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, ®16); + pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD; } void set_pcie_hotplug_bridge(struct pci_dev *pdev) @@ -1326,6 +1328,157 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) return nr; } +static int pcie_find_smpss(struct pci_dev *dev, void *data) +{ + u8 *smpss = data; + + if (!pci_is_pcie(dev)) + return 0; + + /* For PCIE hotplug enabled slots not connected directly to a + * PCI-E root port, there can be problems when hotplugging + * devices. This is due to the possibility of hotplugging a + * device into the fabric with a smaller MPS that the devices + * currently running have configured. Modifying the MPS on the + * running devices could cause a fatal bus error due to an + * incoming frame being larger than the newly configured MPS. + * To work around this, the MPS for the entire fabric must be + * set to the minimum size. Any devices hotplugged into this + * fabric will have the minimum MPS set. If the PCI hotplug + * slot is directly connected to the root port and there are not + * other devices on the fabric (which seems to be the most + * common case), then this is not an issue and MPS discovery + * will occur as normal. + */ + if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) || + (dev->bus->self && + dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT))) + *smpss = 0; + + if (*smpss > dev->pcie_mpss) + *smpss = dev->pcie_mpss; + + return 0; +} + +static void pcie_write_mps(struct pci_dev *dev, int mps) +{ + int rc; + + if (pcie_bus_config == PCIE_BUS_PERFORMANCE) { + mps = 128 << dev->pcie_mpss; + + if (dev->pcie_type != PCI_EXP_TYPE_ROOT_PORT && dev->bus->self) + /* For "Performance", the assumption is made that + * downstream communication will never be larger than + * the MRRS. So, the MPS only needs to be configured + * for the upstream communication. This being the case, + * walk from the top down and set the MPS of the child + * to that of the parent bus. + * + * Configure the device MPS with the smaller of the + * device MPSS or the bridge MPS (which is assumed to be + * properly configured at this point to the largest + * allowable MPS based on its parent bus). + */ + mps = min(mps, pcie_get_mps(dev->bus->self)); + } + + rc = pcie_set_mps(dev, mps); + if (rc) + dev_err(&dev->dev, "Failed attempting to set the MPS\n"); +} + +static void pcie_write_mrrs(struct pci_dev *dev) +{ + int rc, mrrs; + + /* In the "safe" case, do not configure the MRRS. There appear to be + * issues with setting MRRS to 0 on a number of devices. + */ + if (pcie_bus_config != PCIE_BUS_PERFORMANCE) + return; + + /* For Max performance, the MRRS must be set to the largest supported + * value. However, it cannot be configured larger than the MPS the + * device or the bus can support. This should already be properly + * configured by a prior call to pcie_write_mps. + */ + mrrs = pcie_get_mps(dev); + + /* MRRS is a R/W register. Invalid values can be written, but a + * subsequent read will verify if the value is acceptable or not. + * If the MRRS value provided is not acceptable (e.g., too large), + * shrink the value until it is acceptable to the HW. + */ + while (mrrs != pcie_get_readrq(dev) && mrrs >= 128) { + rc = pcie_set_readrq(dev, mrrs); + if (!rc) + break; + + dev_warn(&dev->dev, "Failed attempting to set the MRRS\n"); + mrrs /= 2; + } + + if (mrrs < 128) + dev_err(&dev->dev, "MRRS was unable to be configured with a " + "safe value. If problems are experienced, try running " + "with pci=pcie_bus_safe.\n"); +} + +static int pcie_bus_configure_set(struct pci_dev *dev, void *data) +{ + int mps, orig_mps; + + if (!pci_is_pcie(dev)) + return 0; + + mps = 128 << *(u8 *)data; + orig_mps = pcie_get_mps(dev); + + pcie_write_mps(dev, mps); + pcie_write_mrrs(dev); + + dev_info(&dev->dev, "PCI-E Max Payload Size set to %4d/%4d (was %4d), " + "Max Read Rq %4d\n", pcie_get_mps(dev), 128 << dev->pcie_mpss, + orig_mps, pcie_get_readrq(dev)); + + return 0; +} + +/* pcie_bus_configure_settings requires that pci_walk_bus work in a top-down, + * parents then children fashion. If this changes, then this code will not + * work as designed. + */ +void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss) +{ + u8 smpss; + + if (!pci_is_pcie(bus->self)) + return; + + if (pcie_bus_config == PCIE_BUS_TUNE_OFF) + return; + + /* FIXME - Peer to peer DMA is possible, though the endpoint would need + * to be aware to the MPS of the destination. To work around this, + * simply force the MPS of the entire system to the smallest possible. + */ + if (pcie_bus_config == PCIE_BUS_PEER2PEER) + smpss = 0; + + if (pcie_bus_config == PCIE_BUS_SAFE) { + smpss = mpss; + + pcie_find_smpss(bus->self, &smpss); + pci_walk_bus(bus, pcie_find_smpss, &smpss); + } + + pcie_bus_configure_set(bus->self, &smpss); + pci_walk_bus(bus, pcie_bus_configure_set, &smpss); +} +EXPORT_SYMBOL_GPL(pcie_bus_configure_settings); + unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus) { unsigned int devfn, pass, max = bus->secondary; |