[Gta04-owner] X keycode of the Power button

Neil Jerram neil at ossau.homelinux.net
Mon Nov 7 14:59:22 CET 2011

Hello all...

I'm playing with UIs on my GTA04, and having trouble binding an action 
to the Power button.  The problem seems to be a misunderstanding 
somewhere about what the right keycode is for the Power button.

When I run xev and press the Power button, xev says that the keycode is 
124, and the keysym is XF86PowerOff.  But if I bind XF86PowerOff to an 
action in matchbox-window-manager's config, and run 
matchbox-window-manager with debugging enabled, its output indicates 
that it has mapped XF86PowerOff to keycode 222.  Therefore matchbox 
grabs keycode 222, and the result is that nothing happens when I press 
the button, presumably because the keycode is really 124.

(Also "xmodmap -pk" agrees that the keycode is 124.)

Looking at the source code, matchbox just uses XKeysymToKeycode to do 
the mapping.  So apparently XKeysymToKeycode(XF86PowerOff) == 222.

I'm not sure where to look next for this problem, so can anyone help?  
What determines what the keycode is? - is it evdev config?  Searching 
has turned up hints that it might be invalid to use XKeysymToKeycode is 
XKB is in use; but I'm not sure whether XKB is in use on the GTA04 (or 
what that means).

I should add that this is all after I've added the following lines to 
my xorg.conf:

Section "InputDevice"
         Identifier      "Power Button"
         Driver          "evdev"
         Option          "Device"        "/dev/input/event2"

Section "InputDevice"
         Identifier      "AUX Button"
         Driver          "evdev"
         Option          "Device"        "/dev/input/event0"

+ adding two InputDevice lines in Section "ServerLayout".  Is that an 
OK thing to do?  Is it OK to mix tslib for the touchscreen with evdev 
for Power and AUX buttons?

Finally, another problem is that even after the additions above, 
pressing the AUX button doesn't cause any xev output at all.  Do I need 
to do something else to get it plumbed through to X?  Note that I do see 
stuff if I do "cat /dev/input/event0" and then press AUX, so physically 
and electronically the button is working.

Many thanks for any assistance!


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