xorg-devel Digest, Vol 57, Issue 17

Gene Mosher gene at viewtouch.com
Sun Oct 6 13:26:38 PDT 2013

On 10/06/2013 12:00 PM, xorg-devel-request at lists.x.org wrote:
> Message: 2 Date: Sun, 06 Oct 2013 11:17:13 -0700 From: Keith Packard
> <keithp at keithp.com> To: Mark Kettenis <mark.kettenis at xs4all.nl> Cc:
> xorg-devel at lists.freedesktop.org, kaccardi at gmail.com,
> arjan at linux.intel.com Subject: Re: [PATCH] Close non-keyboard devices
> on DPMS off Message-ID: <86siwe463a.fsf at miki.keithp.com> Content-Type:
> text/plain; charset="utf-8" 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
Keith, why do you want to fix something that isn't broken, by breaking
it?  You say it's hard to imagine a device without *any* keys, well such
'devices' are the ONLY kind of devices I ship running the X server. 
These are not battery operated machines so the advantage of saving power
doesn't exist.  What is wrong with waking up a touchscreen driven
computer by touching the screen?  There's nothing wrong with it! 

--Gene Mosher
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