input devices and hotplugging

Dustin Spicuzza dustin at
Sun Mar 9 19:52:47 PDT 2008


So I'm using this touchscreen with the evtouch driver (yes, I realize 
its external to xorg), and I've ran into two items that cause issues:

a) If the touchscreen isn't on when X comes on, then the device file of 
course doesn't exist, so the driver doesn't initialize
b) If the touchscreen gets turns off, then the device file disappears, 
so the driver stops working, and continues to not work because it needs 
to reopen the device... and it has no clue that it needs to do so
c) /dev/input/mice is out of the question since apparently touchscreens 
don't work too well here (though, I'm not clear why.... though, I've 
read that /dev/input/mice is just a hack anyways)

So.. I've been going though the code for evtouch and other input 
devices, and I'm still not clear about how one would go about making 
hotplugging work.

The only way I can think of fixing (a) is a nasty hack: have the driver 
pretend to initialize anyways and wait for the device to come up, and 
then do normal things when it actually comes up. Is there a better way 
to accomplish this?

If I could somehow send DEVICE_ON and DEVICE_OFF signals to the driver 
using udev, then I'm pretty sure I could solve (b). However, I'm not 
sure how to send the signals (if thats the right term) to the driver... 
though its probably also a hack, its a hack I could live with for 
myself. :)

Any thoughts/suggestions/pointers are appreciated, thanks!


Innovation is just a problem away

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