HID: wacom: Update last_slot_field during pre_report phase
If a touchscreen contains both multitouch and single-touch reports in its descriptor in that order, the driver may overwrite information it saved about the format of the multitouch report. This can cause the report processing code to get tripped up and send an incorrect event stream to userspace. In particular, this can cause last_slot_field to be overwritten with the result that the driver prematurely assumes it has finished processing a slot and sending the ABS_MT_SLOT event at the wrong point in time, associating events for the current contact with the following contact instead. To prevent this from occurring, we update the value of last_slot_field durring the pre_report phase to ensure that it is correct for the report that is to be processed. Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com> Reviewed-by: Ping Cheng <pingc@wacom.com> Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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