On Friday 20 February 2009, Kyle Moffett wrote: > On Fri, Feb 20, 2009 at 10:56 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > * Introduce /sys/power/sleep that will work like /sys/power/state, but: > > - First, it will call ->acknowledge() for each driver (via bus types) to > > check if any of them wants to postpone the suspend (this will prevent tasks > > from being frozen unnecessarily if it is known in advance that the suspend > > should not happen at the moment). > > - Next, it will check the "I_do_not_want_automatic_suspend_to_occur" flag > > of each process and the suspend will be aborted if it is true for any of > > them (quite frankly, I think that should be integrated with the freezer, > > in particular the tasks that have TIF_FREEZE set shouldn't be able to set > > this flag and it should be checked in the freezer loop for every task with > > TIF_FREEZE unset). > > - Next, it will proceed with suspending just like /sys/power/state does (the > > drivers that missed the opportunity to abort the suspend by returning > > 'false' from ->acknowledge() can still abort the suspend by failing their > > ->suspend() routines). > > > > Then, the decision making logic will be able to use /sys/power/sleep whenever > > it wishes to and the kernel will be able to refuse to suspend if it's not > > desirable at the moment. > > Then, for a userspace process handling input events: > > 1) Unset "no-suspend flag" > 2) Poll event device > 3) When the poll returns true, set the "no-suspend flag" > 4) Read the event device and process the event(s) > 5) Go back to step 1 > > The event driver would responsible for atomically preventing suspend > from the moment a button is pressed until it is actually delivered to > a userspace process. Since at that time the userspace process will be > preventing suspend, there will be no window in which we could go to > sleep with pending events. That's correct. How would you like to prevent it from happening? Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
