> On Thu, Jan 29, 2009 at 5:04 AM, Pavel Machek <pavel@xxxxxx> wrote: > > AFAICT, this is something very different. It is attempt to do > > autosuspend right. Imagine burning cd... right now you can suspend, > > and it will just stop the burn. > > > > Wakelocks code allows you to tell the machine 'feel free to suspend > > when you have nothing to do'... so the machine will burn the cd and > > then suspend. > > > > Yes, wakelocks solves this problem, but our auto-suspend code is all > in user-space so the kernel would not have to be involved in that > particular example. > > I added an example to the document that may help illustrate why we > added wakelock support in the kernel: > > --- > Documentation/power/wakelocks.txt > Wakelocks > ========= > > A wakelock prevents the system from entering suspend or other low-power > states when active. If the type is set to WAKE_LOCK_SUSPEND, the wakelock > prevents a full system suspend. If the type is WAKE_LOCK_IDLE, low-power > states that cause large interrupt latencies or that disable a set of > interrupts will not be entered from idle until the wakelocks are released. > > Wakelocks can be used to allow user-space to decide which keys should wake > the system. The sequence of events can look like this: > - The Keypad driver gets an interrupt. It then locks the keypad-scan wakelock > and starts scanning the keypad. > - The keypad-scan code detects a key change and reports it to the input-event > driver. > - The input-event driver sees the key change, enqueues an event, and locks > the input-event-queue wakelock. > - The keypad-scan code detects that no keys are held and unlocks the > keypad-scan wakelock. > - The user-space input-event thread returns from select/poll, locks the > process-input-events wakelock and then calls read in the input-event device. > - The input-event driver dequeues the key-event and, since the queue is now > empty, it unlocks the input-event-queue wakelock. > - The user-space input-event thread returns from read. It determines that the > key should not wake up the system, releases the process-input-events > wakelock and calls select or poll. I don't get it. So you are running userspace while system is suspended? 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
