Re: [PATCH v2 2/8] USB / PCI / PM: Allow the PCI core to do the resume cleanup

[Greg KH <greg@kroah.com>]

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>