On 2014/7/30 11:58, Ethan Zhao wrote: > > >> 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 ? This issue was triggered by firmware set the device mps to 256B. It's not related to platform hardware. I think this is safe, because I only modified the device newly hot-added, this device is not enabled yet. Thanks! Yijing. >>> >>>> 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 >> > > . > -- 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
