On Wed 2015-09-09 11:20:25, Alan Stern wrote: > On Wed, 9 Sep 2015, Rafael J. Wysocki wrote: > > > > The best example and actually the very specific problem we want to > > > solve is handling touchscreens on a phone / tablet. When the screen is > > > turned off, it is ideal to suspend the touchscreen for two reasons: to > > > lower the power consumption as much as possible and to prevent > > > interrupts to wake-up the CPU when the user touches the device, and > > > thus save even more power as we allow the CPU to stay in deep idle > > > states for longer periods. > > > > > > Note that when the screen is turned-on again, we want to resume the > > > touchscreen so that it can send events again. > > > > In fact, then, what you need seems to be the feature discussed by Alan > > and me some time ago allowing remote wakeup do be disabled for runtime > > PM from user space as that in combination with autosuspend should > > address your use case. > > That, plus they want the touchscreen to go into runtime suspend > whenever the screen is off (was this not the main reason for the > patch?). > > It seems to me that it should be possible to arrange for this to happen > simply by making userspace close the touchscreen device when the screen > is turned off. Or am I missing something? Well... that's not what existing userspace expects. Your X windows server will not close the touchscreen. ..and it would be nice to have enough hardware abstraction in the kernel so that X can be used on phones... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
