Input: Improve the events-per-packet estimate

The events-per-packet estimate has so far been used by MT devices
only. This patch adjusts the packet buffer size to also accomodate the
KEY and MSC events.  Keyboards normally send one or two keys at a
time. MT devices normally send a number of button keys along with the
MT information.  The buffer size chosen here covers those cases, and
matches the default buffer size in evdev. Since the input estimate is
now preferred, remove the special input-mt estimate.

Reviewed-and-tested-by: Ping Cheng <pingc@wacom.com>
Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

drivers/input/input-mt.c

@@ -42,7 +42,6 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
 	mt->num_slots = num_slots;
 	input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
 	input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
-	input_set_events_per_packet(dev, 6 * num_slots);
 
 	/* Mark slots as 'unused' */
 	for (i = 0; i < num_slots; i++)

drivers/input/input.c

@@ -1778,6 +1778,9 @@ static unsigned int input_estimate_events_per_packet(struct input_dev *dev)
 		if (test_bit(i, dev->relbit))
 			events++;
 
+	/* Make room for KEY and MSC events */
+	events += 7;
+
 	return events;
 }
 
@@ -1816,6 +1819,7 @@ int input_register_device(struct input_dev *dev)
 {
 	static atomic_t input_no = ATOMIC_INIT(0);
 	struct input_handler *handler;
+	unsigned int packet_size;
 	const char *path;
 	int error;
 
@@ -1828,9 +1832,9 @@ int input_register_device(struct input_dev *dev)
 	/* Make sure that bitmasks not mentioned in dev->evbit are clean. */
 	input_cleanse_bitmasks(dev);
 
-	if (!dev->hint_events_per_packet)
-		dev->hint_events_per_packet =
-				input_estimate_events_per_packet(dev);
+	packet_size = input_estimate_events_per_packet(dev);
+	if (dev->hint_events_per_packet < packet_size)
+		dev->hint_events_per_packet = packet_size;
 
 	/*
 	 * If delay and period are pre-set by the driver, then autorepeating