USB / PCI / PM: Allow the PCI core to do the resume cleanup
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>
Mon, 12 Jun 2017 20:49:40 +0000 (22:49 +0200)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Wed, 14 Jun 2017 22:55:43 +0000 (00:55 +0200)
commitd438aa223e931bfb74dd459bb6c7f3139c48b528
tree00bef41c619fff9bf1a399ecc7b0e148cf05c082
parent64fd1c7040880292710e6592ddc88d0d73cfb6fb
USB / PCI / PM: Allow the PCI core to do the resume cleanup

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>
drivers/usb/core/hcd-pci.c