[PATCH] Close non-keyboard devices on DPMS off
keithp at keithp.com
Sun Oct 6 11:17:13 PDT 2013
Mark Kettenis <mark.kettenis at xs4all.nl> writes:
> Is that really desirable?
It has a couple of benefits -- the first is that touch screens and touch
pads often get input while your laptop screen is closed; this prevents
that from waking up the X server.
The second is that turning off input devices can allow the system to
shut down USB resources and save a bunch of power. I posted the patch so
that we could get measurements of the power savings.
> For me, moving the mouse has always been the most natural way to wake
> up the screen.
Yeah, that's the usual way I wake my machine up as well. However, if you
try this on an OS X machine, you'll find that only the keyboard will
wake the machine up. So, it's not a universal policy at least.
> And I can imagine that touching the screen is the most
> natural way to do it on a device with a touchscreen. Such devices
> might not even have keyboard.
It's hard to imagine a device without *any* keys, but it's certainly
possible. The trick would be to figure out how to detect this
automatically; my machine lists six "keyboard" devices:
↳ Power Button id=6 [slave keyboard (3)]
↳ Power Button id=8 [slave keyboard (3)]
↳ Sleep Button id=9 [slave keyboard (3)]
↳ FaceTime HD Camera (Built-in) id=11 [slave keyboard (3)]
↳ Apple Inc. Apple Internal Keyboard / Trackpad id=12 [slave keyboard (3)]
↳ Video Bus id=7 [slave keyboard (3)]
I think the interesting part here is the potential for power savings
while the screen is blanked; getting some idea of how much closing the
other devices is worth would be really helpful in figuring out when to
make this choice.
keith.packard at intel.com
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