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    SubjectRe: [PATCH 1/2] IB/hfi1: Try slot reset before secondary bus reset
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    On 4/19/2018 4:26 PM, Jason Gunthorpe wrote:
    > On Thu, Apr 19, 2018 at 03:56:23PM -0400, Sinan Kaya wrote:
    >> The infiniband adapter might be connected to a PCI hotplug slot. Performing
    >> secondary bus reset on a hotplug slot causes PCI link up/down interrupts.
    >>
    >> Hotplug driver removes the device from system when a link down interrupt
    >> is observed and performs re-enumeration when link up interrupt is observed.
    >>
    >> This conflicts with what this code is trying to do. Try secondary bus reset
    >> only if pci_reset_slot() fails/unsupported.
    >>
    >> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
    >> drivers/infiniband/hw/hfi1/pcie.c | 3 ++-
    >> 1 file changed, 2 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/drivers/infiniband/hw/hfi1/pcie.c b/drivers/infiniband/hw/hfi1/pcie.c
    >> index 83d66e8..75f49e3 100644
    >> +++ b/drivers/infiniband/hw/hfi1/pcie.c
    >> @@ -908,7 +908,8 @@ static int trigger_sbr(struct hfi1_devdata *dd)
    >
    > The code above this hunk is:
    >
    > /*
    > * Trigger a secondary bus reset (SBR) on ourselves using our parent.
    > *
    > * Based on pci_parent_bus_reset() which is not exported by the
    > * kernel core.
    > */
    > static int trigger_sbr(struct hfi1_devdata *dd)
    > {
    >
    > [..]
    >
    > This really seems like something the PCI core should be helping with,
    > drivers shouldn't be doing stuff like this. I get the feeling this
    > should be a common need if drivers support various error recovery
    > schemes?

    pci_parent_bus_reset() still doesn't deal with hotplug. We need to call
    a variation of pci_slot_reset() before calling pci_parent_bus_reset().

    rc = pci_dev_reset_slot_function(dev, 0);
    if (rc != -ENOTTY)
    return rc;
    return pci_parent_bus_reset(dev, 0);

    VFIO driver does this.

    /* User has access, do the reset */
    ret = slot ? pci_try_reset_slot(vdev->pdev->slot) :
    pci_try_reset_bus(vdev->pdev->bus);

    I assumed the responsibility is at the driver to call the right API it likes.

    --
    Sinan Kaya
    Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
    Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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