Hi! > A system or a device may need to control suspend/wakeup events. It may > want to wakeup the system after a predefined amount of time or at a > predefined event decided while entering suspend for polling or delayed > work. Then, it may want to enter suspend again if its predefined wakeup > condition is the only wakeup reason and there is no outstanding events; > thus, it does not wakeup the userspace unnecessary and keeps suspended > as long as possible (saving the power). Nice. Zaurus needs it, exactly due to this reason: > 2. Execute critical "delayed work" at suspend. > A driver or a system/board may have a delayed work (or any similar > things) that it wants to execute at the requested time. > For example, some chargers want to check the battery voltage some > time (e.g., 30 seconds) after the battery is fully charged and the > charger stops. Then, the charger restarts charging if the voltage has > dropped more than a threshold, which is smaller than "restart-charger" > voltage, which is a threshold to restart charging regardless of the > time passed. Yep, and zaurus also needs it to stop charging. > The system enters the suspend again if and only if all of the following > conditions are met: > 1. None of suspend_again ops returned "I want to stop suspend" > (suspend_again returns SUSPEND_AGAIN_STOP). > 2. At least one of suspend_again ops returned "I want to suspend again" > (suspend_again returns SUSPEND_AGAIN_CONTINUE) Better naming could be SUSPEND_AGAIN and VETO_RESUSPEND or SUSPEND_AGAIN_VETO . > Anyway, the following features may need to be added later: > 1. An API to allow devices to express next desired wakeup-time. Then, > the framework will combine them and setup RTC alarm accordingly and > save/restore previously registered RTC alarms. Yep. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
