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authorLinus Torvalds <torvalds@linux-foundation.org>2011-10-27 08:44:20 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-27 08:44:20 +0200
commit396e6e49c58bb23d1814d3c240c736c9f01523c5 (patch)
treea6ec8dac896c3ea3ac7b1bb0dce8728766afcf91 /Documentation/input/multi-touch-protocol.txt
parent18974369cfe23acf16d0fb79e0d1fba7a9a95ec0 (diff)
parent6ad390a25a9d1d8606b9b826878f0a30639dc2b3 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (68 commits) Input: adp5589-keys - add support for the ADP5585 derivatives Input: imx_keypad - add pm suspend and resume support Input: force feedback - potential integer wrap in input_ff_create() Input: tsc2007 - make sure that X plate resistance is specified Input: serio_raw - fix memory leak when closing char device Input: serio_raw - kick clients when disconnecting port Input: serio_raw - explicitly mark disconnected ports as dead Input: serio_raw - fix coding style issues Input: serio_raw - use dev_*() for messages Input: serio_raw - use bool for boolean data Input: serio_raw - perform proper locking when adding clients to list Input: serio_raw - rename serio_raw_list to serio_raw_client Input: serio_raw - use kref instead of rolling out its own refcounting Input: psmouse - switch to using dev_*() for messages Input: wacom - correct max Y value on medium bamboos Input: wacom - add ABS_DISTANCE to Bamboo Pen reports Input: wacom - remove unneeded touch pressure initialization Input: lm8323 - wrap suspend and resume in CONFIG_PM_SLEEP Input: ad7879-i2c - wrap suspend and resume in CONFIG_PM_SLEEP Input: synaptics_i2c - wrap suspend and resume in CONFIG_PM_SLEEP ...
Diffstat (limited to 'Documentation/input/multi-touch-protocol.txt')
-rw-r--r--Documentation/input/multi-touch-protocol.txt14
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt
index 71536e78406..543101c5bf2 100644
--- a/Documentation/input/multi-touch-protocol.txt
+++ b/Documentation/input/multi-touch-protocol.txt
@@ -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
------------------