Input: alps - v7: sometimes a single touch is reported in mt[1]

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / drivers / input / mouse / alps.c

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index 35a49bf..bfa62a6 100644 (file)
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -919,12 +919,14 @@ static void alps_get_finger_coordinate_v7(struct input_mt_pos *mt,
 
 static int alps_get_mt_count(struct input_mt_pos *mt)
 {
-       int i;
+       int i, fingers = 0;
 
-       for (i = 0; i < MAX_TOUCHES && mt[i].x != 0 && mt[i].y != 0; i++)
-               /* empty */;
+       for (i = 0; i < MAX_TOUCHES; i++) {
+               if (mt[i].x != 0 || mt[i].y != 0)
+                       fingers++;
+       }
 
-       return i;
+       return fingers;
 }
 
 static int alps_decode_packet_v7(struct alps_fields *f,
@@ -938,20 +940,46 @@ static int alps_decode_packet_v7(struct alps_fields *f,
                return 0;
        if (pkt_id == V7_PACKET_ID_UNKNOWN)
                return -1;
+       /*
+        * NEW packets are send to indicate a discontinuity in the finger
+        * coordinate reporting. Specifically a finger may have moved from
+        * slot 0 to 1 or vice versa. INPUT_MT_TRACK takes care of this for
+        * us.
+        *
+        * NEW packets have 3 problems:
+        * 1) They do not contain middle / right button info (on non clickpads)
+        *    this can be worked around by preserving the old button state
+        * 2) They do not contain an accurate fingercount, and they are
+        *    typically send when the number of fingers changes. We cannot use
+        *    the old finger count as that may mismatch with the amount of
+        *    touch coordinates we've available in the NEW packet
+        * 3) Their x data for the second touch is inaccurate leading to
+        *    a possible jump of the x coordinate by 16 units when the first
+        *    non NEW packet comes in
+        * Since problems 2 & 3 cannot be worked around, just ignore them.
+        */
+       if (pkt_id == V7_PACKET_ID_NEW)
+               return 1;
 
        alps_get_finger_coordinate_v7(f->mt, p, pkt_id);
 
-       if (pkt_id == V7_PACKET_ID_TWO || pkt_id == V7_PACKET_ID_MULTI) {
-               f->left = (p[0] & 0x80) >> 7;
-               f->right = (p[0] & 0x20) >> 5;
-               f->middle = (p[0] & 0x10) >> 4;
-       }
+       f->left = (p[0] & 0x80) >> 7;
+       f->right = (p[0] & 0x20) >> 5;
+       f->middle = (p[0] & 0x10) >> 4;
 
        if (pkt_id == V7_PACKET_ID_TWO)
                f->fingers = alps_get_mt_count(f->mt);
-       else if (pkt_id == V7_PACKET_ID_MULTI)
+       else /* pkt_id == V7_PACKET_ID_MULTI */
                f->fingers = 3 + (p[5] & 0x03);
 
+       /* Sometimes a single touch is reported in mt[1] rather then mt[0] */
+       if (f->fingers == 1 && f->mt[0].x == 0 && f->mt[0].y == 0) {
+               f->mt[0].x = f->mt[1].x;
+               f->mt[0].y = f->mt[1].y;
+               f->mt[1].x = 0;
+               f->mt[1].y = 0;
+       }
+
        return 0;
 }