> 在 2014年7月30日，上午11:42，Yijing Wang <wangyijing@xxxxxxxxxx> 写道： > >> On 2014/7/30 11:33, Ethan Zhao wrote: >> Yijing, >> Seems you want to workaround platform bug in generic PCIe hotplug >> code, while not specific to some platforms or devices, that is not >> safe/fair to other vendor's platform. >> and the updating to MPS of device is out of PCIe specification. >> So the best way is to fix within platform, at least, any platform >> specific way in Linux code. > > No, this is not a platform bug, and this is safe, you can refer to my last reply > to Alex. if is not a platform bug, why Didn't other platforms that can do hotplug report such issue ? If it was safe, is it possible that you have all other vendors verify it ? > >> >> Thanks, >> Ethan >> >>> On Tue, Jul 29, 2014 at 4:17 PM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote: >>> Currently we don't update device's mps value when doing >>> pci device hot-add. The hot-added device's mps will be set >>> to default value (128B). But the upstream port device's mps >>> may be larger than 128B which was set by firmware during >>> system bootup. In this case the new added device may not >>> work normally. This issue was found in huawei 5885 server >>> and Dell R620 server. And if we run the platform with windows, >>> this problem is gone. This patch try to update the hot added >>> device mps equal to its parent mps, if device mpss < parent mps, >>> print warning. >>> >>> References: https://bugzilla.kernel.org/show_bug.cgi?id=60671 >>> Reported-by: Keith Busch <keith.busch@xxxxxxxxx> >>> Reported-by: Jordan_Hargrave@xxxxxxxx >>> Reported-by: Yijing Wang <wangyijing@xxxxxxxxxx> >>> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx> >>> Cc: Jon Mason <jdmason@xxxxxxxx> >>> --- >>> drivers/pci/probe.c | 39 +++++++++++++++++++++++++++++++++++++++ >>> 1 files changed, 39 insertions(+), 0 deletions(-) >>> >>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >>> index e3cf8a2..583ca52 100644 >>> --- a/drivers/pci/probe.c >>> +++ b/drivers/pci/probe.c >>> @@ -1613,6 +1613,44 @@ static void pcie_write_mrrs(struct pci_dev *dev) >>> 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"); >>> } >>> >>> +/** >>> + * pcie_bus_update_set - update device mps when device doing hot-add >>> + * @dev: PCI device to set >>> + * >>> + * After device hot add, mps will be set to default(128B), But the >>> + * upstream port device's mps may be larger than 128B which was set >>> + * by firmware during system bootup. Then we should update the device >>> + * mps to equal to its parent mps, Or the device can not work normally. >>> + */ >>> +static void pcie_bus_update_set(struct pci_dev *dev) >>> +{ >>> + int mps, p_mps, mpss; >>> + struct pci_dev *parent; >>> + >>> + if (!pci_is_pcie(dev) || !dev->bus->self >>> + || !dev->bus->self->is_hotplug_bridge) >>> + return; >>> + >>> + parent = dev->bus->self; >>> + mps = pcie_get_mps(dev); >>> + p_mps = pcie_get_mps(parent); >>> + >>> + if (mps >= p_mps) >>> + return; >>> + >>> + mpss = 128 << dev->pcie_mpss; >>> + if (mpss < p_mps) { >>> + dev_warn(&dev->dev, "MPSS %d smaller than upstream MPS %d\n" >>> + "If necessary, use \"pci=pcie_bus_safe\" boot parameter to avoid this problem\n", >>> + mpss, p_mps); >>> + return; >>> + } >>> + >>> + pcie_write_mps(dev, p_mps); >>> + dev_info(&dev->dev, "Max Payload Size set to %4d/%4d (was %4d)\n", >>> + pcie_get_mps(dev), 128 << dev->pcie_mpss, mps); >>> +} >>> + >>> static void pcie_bus_detect_mps(struct pci_dev *dev) >>> { >>> struct pci_dev *bridge = dev->bus->self; >>> @@ -1637,6 +1675,7 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data) >>> return 0; >>> >>> if (pcie_bus_config == PCIE_BUS_TUNE_OFF) { >>> + pcie_bus_update_set(dev); >>> pcie_bus_detect_mps(dev); >>> return 0; >>> } >>> -- >>> 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 >> >> . > > > -- > Thanks! > Yijing > -- 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
