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>
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@ -68,6 +68,22 @@ like:
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SYN_MT_REPORT
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SYN_REPORT
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Here is the sequence after lifting one of the fingers:
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ABS_MT_POSITION_X
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ABS_MT_POSITION_Y
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SYN_MT_REPORT
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SYN_REPORT
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And here is the sequence after lifting the remaining finger:
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SYN_MT_REPORT
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SYN_REPORT
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If the driver reports one of BTN_TOUCH or ABS_PRESSURE in addition to the
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ABS_MT events, the last SYN_MT_REPORT event may be omitted. Otherwise, the
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last SYN_REPORT will be dropped by the input core, resulting in no
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zero-finger event reaching userland.
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Event Semantics
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---------------
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