On Saturday 20 June 2009, Alan Stern wrote: > Some more thoughts... > > Magnus, you might have some insights here. It occurred to me that some > devices can switch power levels very quickly, and the drivers might > therefore want the runtime suspend and resume methods to be called as > soon as possible, even in interrupt context. Then, we'll need special suspend and resume calls for them. > In terms of the current framework, this probably means holding the > runtime PM lock (i.e., not releasing it) across the calls to > ->runtime_suspend and ->runtime_resume. It also means that > pm_request_suspend and pm_request_resume should carry out their jobs > immediately instead of queuing a work item. (Unless the current status > is RPM_SUSPENDING or RPM_RESUMING, which should never happen.) > > Should there be a flag in dev_pm_info to select this behavior? I don't think we should complicate pm_request_suspend() and pm_request_resume() further to handle this particular case. IMO it's better to provide separate core calls for that. > When a device structure is unregistered and deallocated, we have to > insure that there aren't any pending runtime PM workqueue items. > Hence device_del should call a routine that changes the status to an > exceptional state (not RPM_ERROR but something else) to prevent new > requests from being queued, and then calls cancel_work_sync or > cancel_delayed_work_sync as required. This is done in the patch I've just sent. > Similarly, we should insure that runtime PM calls made before the > device is registered don't do anything. So when the device structure > is first created and the contents are all 0, this should also be > interpreted as an exceptional state. We could call it RPM_UNREGISTERED > and use it for both purposes. Hmm. How do you think is possible that the pm_runtime_* functions will be called in such a situation? Best, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
