On Wed, 1 Sep 2010, Colin Cross wrote: > Only wait on a parent device during resume if the parent device is > suspended. > > Consider three drivers, A, B, and C. The parent of A is C, and C > has async_suspend set. On boot, C->power.completion is initialized > to 0. > > During the first suspend: > suspend_devices_and_enter(...) > dpm_resume(...) > device_suspend(A) > device_suspend(B) returns error, aborts suspend > dpm_resume_end(...) > dpm_resume(...) > device_resume(A) > dpm_wait(A->parent == C) > wait_for_completion(C->power.completion) > > The wait_for_completion will never complete, because > complete_all(C->power.completion) will only be called from > device_suspend(C) or device_resume(C), neither of which is called > if suspend is aborted before C. This would work okay if C->power.completion had been initialized to the completed state during boot, right? > After a successful suspend->resume cycle, where B doesn't abort > suspend, C->power.completion is left in the completed state by the > call to device_resume(C), and the same call path will work if B > aborts suspend. > > Signed-off-by: Colin Cross <ccross@xxxxxxxxxxx> > --- > drivers/base/power/main.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index cb784a0..e159910 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -526,7 +526,8 @@ static int device_resume(struct device *dev, pm_message_t state, bool async) > TRACE_DEVICE(dev); > TRACE_RESUME(0); > > - dpm_wait(dev->parent, async); > + if (dev->parent && dev->parent->power.status >= DPM_OFF) > + dpm_wait(dev->parent, async); > device_lock(dev); > > dev->power.status = DPM_RESUMING; I think it would be better to change device_pm_init() and add a complete_all(). Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
