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| author | Henrik Rydberg <rydberg@euromail.se> | 2010-03-21 22:31:26 -0700 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2010-03-21 22:38:56 -0700 |
| commit | 97065e033ec5fd824d0133ecd0c614fe1e5c20bd (patch) | |
| tree | 4914099f6e34c75a6994dd2f90c8236fc808118f /Documentation/input/multi-touch-protocol.txt | |
| parent | d90e6f6aad0ffdc674bc3a05c85c40dcc18e604c (diff) | |
| download | linux-97065e033ec5fd824d0133ecd0c614fe1e5c20bd.tar.gz linux-97065e033ec5fd824d0133ecd0c614fe1e5c20bd.tar.xz | |
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 <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Diffstat (limited to 'Documentation/input/multi-touch-protocol.txt')
| -rw-r--r-- | Documentation/input/multi-touch-protocol.txt | 16 |
1 files changed, 16 insertions, 0 deletions
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 --------------- |