Input: estimate number of events per packet

Calculate a default based on the number of ABS axes, REL axes,
and MT slots for the device during input device registration.

Signed-off-by: Jeff Brown <jeffbrown@android.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

diff --git a/drivers/input/input.c b/drivers/input/input.c
index d6e8bd8..ebbceed 100644 (file)
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1746,6 +1746,42 @@ void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int
 }
 EXPORT_SYMBOL(input_set_capability);
 
+static unsigned int input_estimate_events_per_packet(struct input_dev *dev)
+{
+       int mt_slots;
+       int i;
+       unsigned int events;
+
+       if (dev->mtsize) {
+               mt_slots = dev->mtsize;
+       } else if (test_bit(ABS_MT_TRACKING_ID, dev->absbit)) {
+               mt_slots = dev->absinfo[ABS_MT_TRACKING_ID].maximum -
+                          dev->absinfo[ABS_MT_TRACKING_ID].minimum + 1,
+               clamp(mt_slots, 2, 32);
+       } else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
+               mt_slots = 2;
+       } else {
+               mt_slots = 0;
+       }
+
+       events = mt_slots + 1; /* count SYN_MT_REPORT and SYN_REPORT */
+
+       for (i = 0; i < ABS_CNT; i++) {
+               if (test_bit(i, dev->absbit)) {
+                       if (input_is_mt_axis(i))
+                               events += mt_slots;
+                       else
+                               events++;
+               }
+       }
+
+       for (i = 0; i < REL_CNT; i++)
+               if (test_bit(i, dev->relbit))
+                       events++;
+
+       return events;
+}
+
 #define INPUT_CLEANSE_BITMASK(dev, type, bits)                         \
        do {                                                            \
                if (!test_bit(EV_##type, dev->evbit))                   \
@@ -1793,6 +1829,10 @@ 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);
+
        /*
         * If delay and period are pre-set by the driver, then autorepeating
         * is handled by the driver itself and we don't do it in input.c.

diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
index b3ac06a..318bb82 100644 (file)
--- a/include/linux/input/mt.h
+++ b/include/linux/input/mt.h
@@ -48,6 +48,12 @@ static inline void input_mt_slot(struct input_dev *dev, int slot)
        input_event(dev, EV_ABS, ABS_MT_SLOT, slot);
 }
 
+static inline bool input_is_mt_axis(int axis)
+{
+       return axis == ABS_MT_SLOT ||
+               (axis >= ABS_MT_FIRST && axis <= ABS_MT_LAST);
+}
+
 void input_mt_report_slot_state(struct input_dev *dev,
                                unsigned int tool_type, bool active);