On Tuesday, July 25, 2017 10:05:03 AM Alan Stern wrote:
> On Tue, 25 Jul 2017, Rafael J. Wysocki wrote:
>
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > If HCD_DEAD(hcd) is "true" in check_root_hub_suspended(), it is
> > rather pointless to check the secondary root hub, so return early
> > then.
> >
> > This actually fixes occasional suspend failures on one of my test
> > machines.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > ---
> > drivers/usb/core/hcd-pci.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > 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
> > @@ -427,6 +427,9 @@ static int check_root_hub_suspended(stru
> > dev_warn(dev, "Root hub is not suspended\n");
> > return -EBUSY;
> > }
> > + if (HCD_DEAD(hcd))
> > + return 0;
> > +
> > if (hcd->shared_hcd) {
> > hcd = hcd->shared_hcd;
> > if (HCD_RH_RUNNING(hcd)) {
>
> While this is an okay solution, IMO it would be more reliable and more
> general to have usb_hc_died() clear the HCD_FLAG_RH_RUNNING bit and set
> the HCD_FLAG_DEAD bit in the shared hcd. Right now it only does these
> things for the primary.
>
> Would you like to write and test a patch to do that?
I can do that.
> Incidentally, if this fixes occasional suspend failures on your test
> machine, does that mean the test machine's host controller occasionally
> dies? Maybe that should be fixed too...
Yes, it does sometimes.
What appears to happen is that the platform does not initialize properly
sometimes after a reset and then the HCD dies during suspend.
So reproduction may be somewhat tricky, but oh well.
Thanks,
Rafael
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