From 97065e033ec5fd824d0133ecd0c614fe1e5c20bd Mon Sep 17 00:00:00 2001 From: Henrik Rydberg Date: Sun, 21 Mar 2010 22:31:26 -0700 Subject: Input: clarify the no-finger event in multitouch protocol The current documentation does not explicitly specify how to report zero fingers, leaving a potential problem in the driver implementations and giving no parsing directive to userland. This patch defines two equally valid ways. Signed-off-by: Henrik Rydberg Signed-off-by: Dmitry Torokhov --- Documentation/input/multi-touch-protocol.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'Documentation/input') diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt index 8490480ce43..eacb2260666 100644 --- a/Documentation/input/multi-touch-protocol.txt +++ b/Documentation/input/multi-touch-protocol.txt @@ -68,6 +68,22 @@ like: SYN_MT_REPORT SYN_REPORT +Here is the sequence after lifting one of the fingers: + + ABS_MT_POSITION_X + ABS_MT_POSITION_Y + SYN_MT_REPORT + SYN_REPORT + +And here is the sequence after lifting the remaining finger: + + SYN_MT_REPORT + SYN_REPORT + +If the driver reports one of BTN_TOUCH or ABS_PRESSURE in addition to the +ABS_MT events, the last SYN_MT_REPORT event may be omitted. Otherwise, the +last SYN_REPORT will be dropped by the input core, resulting in no +zero-finger event reaching userland. Event Semantics --------------- -- cgit v1.2.3