[PATCH libevdev 0/3] SYN_DROPPED syncing fixes - once again

[Peter Hutterer]

I've spent a few days tracking down a synaptics bug that caused stuck
touches in the driver. The cause turned out to be a double tracking ID event
in a slot after SYN_DROPPED handling. And quite simple to reproduce too: if
a tracking ID comes in after the SYN_DROPPED, we generate the tracking ID
event in the sync process, but still process the actual event when it is
read from the kernel.

The (only?) solution here is to drain all events after SYN_DROPPED, sync the
device and then continue from there. 

Cheers,
  Peter