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.
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;
--
1.7.1
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