Input: multitouch - add tracking ID to the protocol

There are a few multi-touch devices that support finger tracking
well in hardware, Stantum being the prime example. By exposing the
tracking ID in the MT protocol, evdev bandwidth and cpu usage in
user space can be reduced.

This patch adds the ABS_MT_TRACKING_ID to the MT protocol.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Tested-by: Stéphane Chatty <chatty@enac.fr>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

diff --git a/drivers/input/input.c b/drivers/input/input.c
index e54e002..5d445f4 100644 (file)
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -42,6 +42,7 @@ static unsigned int input_abs_bypass_init_data[] __initdata = {
        ABS_MT_POSITION_Y,
        ABS_MT_TOOL_TYPE,
        ABS_MT_BLOB_ID,
+       ABS_MT_TRACKING_ID,
        0
 };
 static unsigned long input_abs_bypass[BITS_TO_LONGS(ABS_CNT)];

diff --git a/include/linux/input.h b/include/linux/input.h
index 0e6ff5d..6fed4f6 100644 (file)
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -656,6 +656,7 @@ struct input_absinfo {
 #define ABS_MT_POSITION_Y      0x36    /* Center Y ellipse position */
 #define ABS_MT_TOOL_TYPE       0x37    /* Type of touching device */
 #define ABS_MT_BLOB_ID         0x38    /* Group a set of packets as a blob */
+#define ABS_MT_TRACKING_ID     0x39    /* Unique ID of initiated contact */
 
 #define ABS_MAX                        0x3f
 #define ABS_CNT                        (ABS_MAX+1)