as a scroll wheel.  Scroll data is reported as packets with w == 2 and
the scroll amount in byte 1, treated as a signed character.  For some
reason, the smallest possible wheel movement is reported as a scroll
amount of 4 units.  This amount is typically spread out over more than
one packet, so the driver has to accumulate scroll delta values to
correctly deal with this.
Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>