On Wed, 28 Jul 2010, Raj Kumar wrote: > Hi ALan, > > > > 1) As you mentioned that -EBUSY code is appropriate, But if the > > device started doing activities during that time then it is not appropriate > > to check every time if device is idle. > > > > Because if -EBUSY is returned, then workqueue thread will check again and again > > that if the device is idle. > > > > if (notify) > __pm_runtime_idle(dev); > > > That is notify flag will be true. right? Yes. But the thread won't check again and again; it will check only once. Your runtime_idle callback will know that the device is busy, and therefore it won't schedule another suspend on the workqueue. Not until the device really becomes idle again. > 2) The 2nd thing is use case of deep sleep state i.e. system suspend. > > > > Suppose device is active and its run time status is active. Now when the system suspend > > happens, it will increment usage_counter of device in power management framework, > > > > now at that time since clocks and power are enabled, So what will device do? It will continue running normally until the driver's suspend callback is invoked. > My point is when system suspend comes to device and device is doing activities at that time, > > if the device will ask run time power management to shut its clock off and make it suspended, > > > > and then it respond to system suspend???? The _device_ doesn't do any of these things; the _driver_ does them. During system suspend, the driver has to shut off the clock and suspend the device. It can't do these things by using runtime PM calls; it has to do them some other way. > Run time power management will not do at the time as its usage counter is already increased, > > > > Right? so what about this use case when this kind of overlapping occurs? Right. During system suspend, the driver has to do its job without using runtime PM. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
