ANDROID: virtio: virtio_input: Set the amount of multitouch slots in virtio input

Virtio input was missing the the amount of multitouch
slots and kernel was filtering out ABS_MT_SLOT events
for a screen is touched in more than one place.

Bug: 143488374
Signed-off-by: Roman Kiryanov <rkir@google.com>
Change-Id: I617099435af311e6b0ee127b76eafe13834ea8f8
Signed-off-by: Yang, Dong <dong.yang@intel.com>

Author: Roman Kiryanov

drivers/virtio/virtio_input.c

@@ -3,6 +3,7 @@
 #include <linux/virtio.h>
 #include <linux/virtio_config.h>
 #include <linux/input.h>
+#include <linux/input/mt.h>
 
 #include <uapi/linux/virtio_ids.h>
 #include <uapi/linux/virtio_input.h>
@@ -164,6 +165,12 @@ static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
 	virtio_cread(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);
 	input_set_abs_params(vi->idev, abs, mi, ma, fu, fl);
 	input_abs_set_res(vi->idev, abs, re);
+	if (abs == ABS_MT_TRACKING_ID)
+		input_mt_init_slots(vi->idev,
+				    ma, /* input max finger */
+				    INPUT_MT_DIRECT
+					| INPUT_MT_DROP_UNUSED
+					| INPUT_MT_TRACK);
 }
 
 static int virtinput_init_vqs(struct virtio_input *vi)