Hmm. I just added very similar code for setting PCIEmaxpayload during PCIE hotplug insertion. perhaps these two should be merged? --jordan hargrave Dell Enterprise Linux Engineering > -----Original Message----- > From: linux-pci-owner@xxxxxxxxxxxxxxx [mailto:linux-pci- > owner@xxxxxxxxxxxxxxx] On Behalf Of Jon Mason > Sent: Wednesday, May 25, 2011 2:01 PM > To: Jesse Barnes > Cc: linux-pci@xxxxxxxxxxxxxxx; Andrew Gallatin > Subject: [PATCH] PCI: Max Payload Size BIOS workaround > > Ensure that the max payload size on the root port is the same as the > max > payload size on all intermediate bridges and devices. This is required > to work around buggy BIOS revisions found on various whitebox > motherboards which do not configure mps beyond one level below the root > port. > > Signed-off-by: Jon Mason <mason@xxxxxxxx> > Signed-off-by: Andrew Gallatin <gallatin@xxxxxxxx> > --- > drivers/pci/bus.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 44 insertions(+), 0 deletions(-) > > diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c > index 69546e9..fc16b67 100644 > --- a/drivers/pci/bus.c > +++ b/drivers/pci/bus.c > @@ -175,6 +175,49 @@ int pci_bus_add_child(struct pci_bus *bus) > return retval; > } > > +/* > + * Ensure that the max payload size on the root port is the same as > the max > + * payload size on all intermediate bridges. This is required to work > around > + * buggy BIOS revisions found on various whitebox motherboards which > do not > + * configure mps beyond one level below the root port. > + */ > +static void pci_mps_workaround(struct pci_dev *child, struct pci_dev > *parent) > +{ > + u16 val, pmps, cmps; > + int cap, rc; > + > + if (!parent) > + return; > + > + cap = pci_find_capability(parent, PCI_CAP_ID_EXP); > + if (!cap) > + return; > + > + rc = pci_read_config_word(parent, cap + PCI_EXP_DEVCTL, &val); > + if (rc) > + return; > + > + pmps = val & PCI_EXP_DEVCTL_PAYLOAD; > + > + cap = pci_find_capability(child, PCI_CAP_ID_EXP); > + if (!cap) > + return; > + > + rc = pci_read_config_word(child, cap + PCI_EXP_DEVCTL, &val); > + if (rc) > + return; > + > + cmps = val & PCI_EXP_DEVCTL_PAYLOAD; > + > + if (pmps != cmps) { > + printk(KERN_WARNING "Child MPS of %d != Parent MPS of %d! > " > + "Most likely caused by bad BIOS. Working > around...\n", > + 128 << (cmps >> 5), 128 << (pmps >> 5)); > + val = (val & ~ PCI_EXP_DEVCTL_PAYLOAD) | pmps; > + pci_write_config_word(child, cap + PCI_EXP_DEVCTL, val); > + } > +} > + > /** > * pci_bus_add_devices - insert newly discovered PCI devices > * @bus: bus to check for new devices > @@ -194,6 +237,7 @@ void pci_bus_add_devices(const struct pci_bus *bus) > int retval; > > list_for_each_entry(dev, &bus->devices, bus_list) { > + pci_mps_workaround(dev, dev->bus->self); > /* Skip already-added devices */ > if (dev->is_added) > continue; > -- > 1.7.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
