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authorCharlie Mooney <charliemooney@chromium.org>2015-03-20 09:40:17 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2015-03-20 09:45:28 -0700
commita736775db683174269c65c7c5cc8e5ee534e7681 (patch)
tree7771241d9f3e0eb75125ea5f16c1877a8cd78995 /Documentation/input
parent09d042a2eb90ee2c86d80c48ad096ae3f5776cef (diff)
downloadlinux-a736775db683174269c65c7c5cc8e5ee534e7681.tar.bz2
Input: add MT_TOOL_PALM
Currently there are only two "tools" that can be specified by a multi-touch driver: MT_TOOL_FINGER and MT_TOOL_PEN. In working with Elan (The touch vendor) and discussing their next-gen devices it seems that it will be useful to have more tools so that their devices can give the upper layers of the stack hints as to what is touching the sensor. In particular they have new experimental firmware that can better differentiate between palms vs fingertips and would like to plumb a patch so that we can use their hints in higher-level gesture soft- ware. The firmware on the device can reasonably do a better job of palm detection because it has access to all of the raw sensor readings as opposed to just the width/pressure/etc that are exposed by the driver. As such, the firmware can characterize what a palm looks like in much finer-grained detail and this change would allow such a device to share its findings with the kernel. Signed-off-by: Charlie Mooney <charliemooney@chromium.org> Acked-by: Peter Hutterer <peter.hutterer@who-t.net> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/input')
-rw-r--r--Documentation/input/multi-touch-protocol.txt9
1 files changed, 6 insertions, 3 deletions
diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt
index 7b4f59c09ee2..b85d000faeb4 100644
--- a/Documentation/input/multi-touch-protocol.txt
+++ b/Documentation/input/multi-touch-protocol.txt
@@ -312,9 +312,12 @@ ABS_MT_TOOL_TYPE
The type of approaching tool. A lot of kernel drivers cannot distinguish
between different tool types, such as a finger or a pen. In such cases, the
-event should be omitted. The protocol currently supports MT_TOOL_FINGER and
-MT_TOOL_PEN [2]. For type B devices, this event is handled by input core;
-drivers should instead use input_mt_report_slot_state().
+event should be omitted. The protocol currently supports MT_TOOL_FINGER,
+MT_TOOL_PEN, and MT_TOOL_PALM [2]. For type B devices, this event is handled
+by input core; drivers should instead use input_mt_report_slot_state().
+A contact's ABS_MT_TOOL_TYPE may change over time while still touching the
+device, because the firmware may not be able to determine which tool is being
+used when it first appears.
ABS_MT_BLOB_ID