Input: mt - document devices reporting more touches than slots
Some devices are capable of identifying and/or tracking more contacts than they can report to the driver. Document how a driver should handle this, and what userspace should expect. Signed-off-by: Daniel Kurtz <djkurtz@chromium.org> Acked-by: Chase Douglas <chase.douglas@canonical.com> Acked-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Родитель
a6ca40c11e
Коммит
a93bd154d8
|
@ -65,6 +65,20 @@ the full state of each initiated contact has to reside in the receiving
|
|||
end. Upon receiving an MT event, one simply updates the appropriate
|
||||
attribute of the current slot.
|
||||
|
||||
Some devices identify and/or track more contacts than they can report to the
|
||||
driver. A driver for such a device should associate one type B slot with each
|
||||
contact that is reported by the hardware. Whenever the identity of the
|
||||
contact associated with a slot changes, the driver should invalidate that
|
||||
slot by changing its ABS_MT_TRACKING_ID. If the hardware signals that it is
|
||||
tracking more contacts than it is currently reporting, the driver should use
|
||||
a BTN_TOOL_*TAP event to inform userspace of the total number of contacts
|
||||
being tracked by the hardware at that moment. The driver should do this by
|
||||
explicitly sending the corresponding BTN_TOOL_*TAP event and setting
|
||||
use_count to false when calling input_mt_report_pointer_emulation().
|
||||
The driver should only advertise as many slots as the hardware can report.
|
||||
Userspace can detect that a driver can report more total contacts than slots
|
||||
by noting that the largest supported BTN_TOOL_*TAP event is larger than the
|
||||
total number of type B slots reported in the absinfo for the ABS_MT_SLOT axis.
|
||||
|
||||
Protocol Example A
|
||||
------------------
|
||||
|
|
Загрузка…
Ссылка в новой задаче