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    SubjectRe: [PATCH v2 2/8] USB / PCI / PM: Allow the PCI core to do the resume cleanup
    On Mon, Jun 12, 2017 at 10:49:40PM +0200, Rafael J. Wysocki wrote:
    > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >
    > hcd_pci_resume_noirq() used as a universal _resume_noirq handler for
    > PCI USB controllers calls pci_back_from_sleep() which is unnecessary
    > and may become problematic.
    >
    > It is unnecessary, because the PCI bus type carries out post-suspend
    > cleanup of all PCI devices during resume and that covers all things
    > done by the pci_back_from_sleep(). There is no reason why USB cannot
    > follow all of the other PCI devices in that respect.
    >
    > It will become problematic after subsequent changes that make it
    > possible to go back to sleep again after executing dpm_resume_noirq()
    > if no valid system wakeup events have been detected at that point.
    > Namely, calling pci_back_from_sleep() at the _resume_noirq stage
    > will cause the wakeup status of the devices in question to be cleared
    > and if any of them has triggered system wakeup, that event may be
    > missed then.
    >
    > For the above reasons, drop the pci_back_from_sleep() invocation
    > from hcd_pci_resume_noirq().
    >
    > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    > Acked-by: Alan Stern <stern@rowland.harvard.edu>

    Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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