Re: [PATCH] usb: Add support for runtime power management of the hcd

Oliver Neukum
2009-11-11T11:34:43Z

Am Dienstag, 10. November 2009 16:04:12 schrieb Alan Stern:
> D's driver will field the interrupt request and will call something
> like pm_request_resume(), to schedule a workqueue item for a runtime
> resume of D. However, the runtime-PM workqueues are either frozen or
> in some other way prevented from doing anything while the system sleep
> transition is in progress.
>
> Therefore the wakeup request will get lost. The information is still
> present, in the form of a work_struct, but it won't get acted on until
> the system wakes up. In particular, it won't prevent the sleep
> transition from completing and it won't cause the system to wake up
> immediately after going to sleep.
>
> This suggests that pm_request_resume() should abort a sleep transition
> if one is already in progress. Rafael, what do you think?

That seems to be a bit harsh. If you do not specify that a device be
able to wake the whole system, why would it be good for a request
coming from it to abort a system sleep transition?

Regards
Oliver
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