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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>
This commit is contained in:
Henrik Rydberg 2010-03-21 22:31:26 -07:00 committed by Dmitry Torokhov
parent d90e6f6aad
commit 97065e033e
1 changed files with 16 additions and 0 deletions
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16
Documentation/input/multi-touch-protocol.txt
View File

@ -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
---------------