input: Set default events per packet for MT devices.

Use the number of ABS_MT_SLOTs or ABS_MT_TRACKING_IDs to choose a
default number of events per packet.

Signed-off-by: jeffbrown@android.com

diff --git a/drivers/input/input.c b/drivers/input/input.c
index ab6982056518e3c086c57738f360574b211108aa..5dc12e173ad387d745bb35d53f6fd25e9767f610 100644 (file)
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1700,6 +1700,27 @@ void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int
 }
 EXPORT_SYMBOL(input_set_capability);
 
+static void input_set_default_events_per_packet(struct input_dev *dev)
+{
+       int slots;
+
+       if (dev->hint_events_per_packet)
+               return;
+
+       if (dev->mtsize)
+               slots = dev->mtsize;
+       else if (test_bit(ABS_MT_TRACKING_ID, dev->absbit))
+               slots = min(20, dev->absinfo[ABS_MT_TRACKING_ID].maximum -
+                       dev->absinfo[ABS_MT_TRACKING_ID].minimum + 1);
+       else if (test_bit(ABS_MT_POSITION_X, dev->absbit))
+               slots = 2;
+       else
+               slots = 0;
+
+       if (slots)
+               input_set_events_per_packet(dev, slots * 10);
+}
+
 #define INPUT_CLEANSE_BITMASK(dev, type, bits)                         \
        do {                                                            \
                if (!test_bit(EV_##type, dev->evbit))                   \
@@ -1738,6 +1759,9 @@ int input_register_device(struct input_dev *dev)
        const char *path;
        int error;
 
+       /* Use a larger default input buffer for MT devices */
+       input_set_default_events_per_packet(dev);
+
        /* Every input device generates EV_SYN/SYN_REPORT events. */
        __set_bit(EV_SYN, dev->evbit);