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>
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