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    Subject[PATCH v3 2/2] USB: hcd-pci: Fully suspend across freeze/thaw cycle
    Date
    The documentation for the freeze() method says that it "should quiesce
    the device so that it doesn't generate IRQs or DMA". The unspoken
    consequence of not doing this is that MSIs aimed at non-boot CPUs may
    get fully lost if they're sent during the period where the target CPU is
    offline.

    The current callbacks for USB HCD do not fully quiesce interrupts,
    specifically on XHCI. Change to use the full suspend/resume flow for
    freeze/thaw to ensure interrupts are fully quiesced. This fixes issues
    where USB devices fail to thaw during hibernation because XHCI misses
    its interrupt and cannot recover.

    Signed-off-by: Evan Green <evgreen@chromium.org>
    Acked-by: Alan Stern <stern@rowland.harvard.edu>

    ---

    (no changes since v2)

    Changes in v2:
    - Removed the change to freeze_noirq/thaw_noirq

    drivers/usb/core/hcd-pci.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
    index 8176bc81a635d6..ae5e6d572376be 100644
    --- a/drivers/usb/core/hcd-pci.c
    +++ b/drivers/usb/core/hcd-pci.c
    @@ -616,10 +616,10 @@ const struct dev_pm_ops usb_hcd_pci_pm_ops = {
    .suspend_noirq = hcd_pci_suspend_noirq,
    .resume_noirq = hcd_pci_resume_noirq,
    .resume = hcd_pci_resume,
    - .freeze = check_root_hub_suspended,
    + .freeze = hcd_pci_suspend,
    .freeze_noirq = check_root_hub_suspended,
    .thaw_noirq = NULL,
    - .thaw = NULL,
    + .thaw = hcd_pci_resume,
    .poweroff = hcd_pci_suspend,
    .poweroff_noirq = hcd_pci_suspend_noirq,
    .restore_noirq = hcd_pci_resume_noirq,
    --
    2.31.0
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