From: Henrik Rydberg Date: Mon, 22 Mar 2010 05:31:26 +0000 (-0700) Subject: Input: clarify the no-finger event in multitouch protocol X-Git-Tag: firefly_0821_release~9833^2~2172^2~21 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=97065e033ec5fd824d0133ecd0c614fe1e5c20bd;p=firefly-linux-kernel-4.4.55.git 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 --- diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt index 8490480ce432..eacb22606664 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 ---------------