| Message ID | 1565826.hIbT8kZpDn@aspire.rjw.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Thu, 8 Jun 2017, 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> > --- > 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@rowland.harvard.edu>
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@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> > > --- > > 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@rowland.harvard.edu> Thanks!
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; }