Re: [linux-pm] [RFC] input: syfs switches for SKE keypad

Pavel Machek
2010-10-13T19:20:59Z

Hi!

On Wed 2010-10-13 19:35:49, Ferenc Wagner wrote:
> Pavel Machek <pavel@ucw.cz> writes:
>
> >> For mobile devices it is not acceptable to filter events away at some
> >> upper SW layer depending on the system state. The HW which generates
> >> those events may not generate events at all to allow longer CPU sleep
> >> periods.

Actually, I question this, too.

Obviously, touchscreen needs to be turned off, but how common are
accidental button presses?

> >> In ideal world it would be nice to control device states based on for
> >> example user count. However, there are several listeners for input
> >> devices and it is hard or impossible to have them all to follow overall
> >> state transition (screen blanked etc.). Instead, there is some
> >> system
> >
> > So you have mobile device; why is it impossible to just close the
> > device when you do not want the events? I guess it is hard for generic
> > distros, but on your phone, you should be able to modify Xserver to
> > close touchscreen/keypad device when it is not needed... right?
>
> We'd had this discussion before... cf. eg.
> http://thread.gmane.org/gmane.linux.kernel.input/9266/focus=9767
>
> The problem was that several processes may have a device open, while
> another process should be able to control the state of the device.
> Maybe this could be solved by making the controlling process a proxy,
> and having all "user" processes going though it. Then the

Yes, and the proxy is normally called "X server". We already have it.

> (proxy) process could open/close the device as it wants, letting the
> runtime PM do its job. But this would mean duplicating some kernel
> functionality (at least multiplexing) in user space.

Yes. We already do that.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html