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path: root/drivers/input/input.c
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-rw-r--r--drivers/input/input.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/input/input.c b/drivers/input/input.c
index a9b025f4147a..ab6982056518 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1599,11 +1599,14 @@ EXPORT_SYMBOL(input_free_device);
* @dev: input device supporting MT events and finger tracking
* @num_slots: number of slots used by the device
*
- * This function allocates all necessary memory for MT slot handling
- * in the input device, and adds ABS_MT_SLOT to the device capabilities.
+ * This function allocates all necessary memory for MT slot handling in the
+ * input device, and adds ABS_MT_SLOT to the device capabilities. All slots
+ * are initially marked as unused iby setting ABS_MT_TRACKING_ID to -1.
*/
int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
{
+ int i;
+
if (!num_slots)
return 0;
@@ -1614,6 +1617,10 @@ int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
dev->mtsize = num_slots;
input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
+ /* Mark slots as 'unused' */
+ for (i = 0; i < num_slots; i++)
+ dev->mt[i].abs[ABS_MT_TRACKING_ID - ABS_MT_FIRST] = -1;
+
return 0;
}
EXPORT_SYMBOL(input_mt_create_slots);