On Mon, Aug 26, 2013 at 2:33 AM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote: > Some broken BIOS configures incorrect mps for devices, > eg. bridge mps larger than connected Endpoint device mps. > So TLP packets maybe discarded by Endpoint device. > These devices may not work normally. Joe Jin reported > these problems, reference: > http://lkml.kernel.org/r/4FFA9B96.6040901@xxxxxxxxxx > http://lkml.kernel.org/r/509B5038.8090304@xxxxxxxxxx > For easy detect this issue, try to detect the unsafe mps > (unequal mps between device and its bridge device) > setting. If unsafe mps setting found, print warning message. > > Reported-by: Joe Jin <joe.jin@xxxxxxxxxx> > Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx> > Cc: Jon Mason <jdmason@xxxxxxxx> Applied with minor tweaks to pci/yijing-mps-v8 > --- > drivers/pci/probe.c | 25 ++++++++++++++++++++++--- > 1 files changed, 22 insertions(+), 3 deletions(-) > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 21ca9a1..e442744 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -1587,6 +1587,23 @@ static void pcie_write_mrrs(struct pci_dev *dev) > "with pci=pcie_bus_safe.\n"); > } > > +static void pcie_bus_detect_mps(struct pci_dev *dev) > +{ > + int mps, p_mps; > + > + if (!dev->bus->self) > + return; > + > + mps = pcie_get_mps(dev); > + p_mps = pcie_get_mps(dev->bus->self); > + > + if (mps != p_mps) > + dev_warn(&dev->dev, "Non-optimal MPS value of %d being used. " > + "If problems are experienced, try running with " > + "pci=pcie_bus_safe.\n", mps); > + return; > +} > + > static int pcie_bus_configure_set(struct pci_dev *dev, void *data) > { > int mps, orig_mps; > @@ -1594,6 +1611,11 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data) > if (!pci_is_pcie(dev)) > return 0; > > + if (pcie_bus_config == PCIE_BUS_TUNE_OFF) { > + pcie_bus_detect_mps(dev); > + return 0; > + } > + > mps = 128 << *(u8 *)data; > orig_mps = pcie_get_mps(dev); > > @@ -1621,9 +1643,6 @@ void pcie_bus_configure_settings(struct pci_bus *bus) > 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 of the MPS of the destination. To work around this, > * simply force the MPS of the entire system to the smallest possible. > -- > 1.7.1 > > -- 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
