On Thursday, June 08, 2017 11:24:55 AM Alan Stern wrote:
> On Thu, 8 Jun 2017, Rafael J. Wysocki wrote:
>
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > 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@xxxxxxxxx>
> > ---
> > drivers/usb/core/hcd-pci.c | 7 +------
> > 1 file changed, 1 insertion(+), 6 deletions(-)
> >
> > Index: linux-pm/drivers/usb/core/hcd-pci.c
> > ===================================================================
> > --- linux-pm.orig/drivers/usb/core/hcd-pci.c
> > +++ linux-pm/drivers/usb/core/hcd-pci.c
> > @@ -584,12 +584,7 @@ static int hcd_pci_suspend_noirq(struct
> >
> > static int hcd_pci_resume_noirq(struct device *dev)
> > {
> > - struct pci_dev *pci_dev = to_pci_dev(dev);
> > -
> > - powermac_set_asic(pci_dev, 1);
> > -
> > - /* Go back to D0 and disable remote wakeup */
> > - pci_back_from_sleep(pci_dev);
> > + powermac_set_asic(to_pci_dev(dev), 1);
> > return 0;
> > }
>
> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Thanks!
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