Input: appletouch - fix jumps when additional fingers are detected

Addresses issues related to when a second finger enters or leaves the
field, causing the cursor to jump or the page to scroll unexpectedly; now,
we discard any movement change that happens at the exact moment we detect a
change in the number of fingers touching the trackpad. This doesn't
completely resolve the issue but does greatly mitigate it.

Signed-off-by: Clinton Sprain <clintonsprain@gmail.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 21 insertions, 6 deletions

diff --git a/drivers/input/mouse/appletouch.c b/drivers/input/mouse/appletouch.c
index 2dbf7a0f0537..ef234c9b2f2f 100644
--- a/drivers/input/mouse/appletouch.c
+++ b/drivers/input/mouse/appletouch.c
@@ -218,6 +218,7 @@ struct atp {
         bool                    valid;          /* are the samples valid? */
         bool                    size_detect_done;
         bool                    overflow_warned;
+        int                     fingers_old;    /* last reported finger count */
         int                     x_old;          /* last reported x/y, */
         int                     y_old;          /* used for smoothing */
         signed char             xy_cur[ATP_XSENSORS + ATP_YSENSORS];
@@ -528,7 +529,7 @@ static void atp_complete_geyser_1_2(struct urb *urb)
 {
         int x, y, x_z, y_z, x_f, y_f;
         int retval, i, j;
-        int key;
+        int key, fingers;
         struct atp *dev = urb->context;
         int status = atp_status_check(urb);
 
@@ -611,7 +612,9 @@ static void atp_complete_geyser_1_2(struct urb *urb)
                               dev->info->yfact, &y_z, &y_f);
         key = dev->data[dev->info->datalen - 1] & ATP_STATUS_BUTTON;
 
-        if (x && y) {
+        fingers = max(x_f, y_f);
+
+        if (x && y && fingers == dev->fingers_old) {
                 if (dev->x_old != -1) {
                         x = (dev->x_old * 7 + x) >> 3;
                         y = (dev->y_old * 7 + y) >> 3;
@@ -628,7 +631,7 @@ static void atp_complete_geyser_1_2(struct urb *urb)
                         input_report_abs(dev->input, ABS_Y, y);
                         input_report_abs(dev->input, ABS_PRESSURE,
                                          min(ATP_PRESSURE, x_z + y_z));
-                        atp_report_fingers(dev->input, max(x_f, y_f));
+                        atp_report_fingers(dev->input, fingers);
                 }
                 dev->x_old = x;
                 dev->y_old = y;
@@ -636,6 +639,7 @@ static void atp_complete_geyser_1_2(struct urb *urb)
         } else if (!x && !y) {
 
                 dev->x_old = dev->y_old = -1;
+                dev->fingers_old = 0;
                 input_report_key(dev->input, BTN_TOUCH, 0);
                 input_report_abs(dev->input, ABS_PRESSURE, 0);
                 atp_report_fingers(dev->input, 0);
@@ -644,6 +648,10 @@ static void atp_complete_geyser_1_2(struct urb *urb)
                 memset(dev->xy_acc, 0, sizeof(dev->xy_acc));
         }
 
+        if (fingers != dev->fingers_old)
+                dev->x_old = dev->y_old = -1;
+        dev->fingers_old = fingers;
+
         input_report_key(dev->input, BTN_LEFT, key);
         input_sync(dev->input);
 
@@ -661,7 +669,7 @@ static void atp_complete_geyser_3_4(struct urb *urb)
 {
         int x, y, x_z, y_z, x_f, y_f;
         int retval, i, j;
-        int key;
+        int key, fingers;
         struct atp *dev = urb->context;
         int status = atp_status_check(urb);
 
@@ -724,7 +732,9 @@ static void atp_complete_geyser_3_4(struct urb *urb)
 
         key = dev->data[dev->info->datalen - 1] & ATP_STATUS_BUTTON;
 
-        if (x && y) {
+        fingers = max(x_f, y_f);
+
+        if (x && y && fingers == dev->fingers_old) {
                 if (dev->x_old != -1) {
                         x = (dev->x_old * 7 + x) >> 3;
                         y = (dev->y_old * 7 + y) >> 3;
@@ -741,7 +751,7 @@ static void atp_complete_geyser_3_4(struct urb *urb)
                         input_report_abs(dev->input, ABS_Y, y);
                         input_report_abs(dev->input, ABS_PRESSURE,
                                          min(ATP_PRESSURE, x_z + y_z));
-                        atp_report_fingers(dev->input, max(x_f, y_f));
+                        atp_report_fingers(dev->input, fingers);
                 }
                 dev->x_old = x;
                 dev->y_old = y;
@@ -749,6 +759,7 @@ static void atp_complete_geyser_3_4(struct urb *urb)
         } else if (!x && !y) {
 
                 dev->x_old = dev->y_old = -1;
+                dev->fingers_old = 0;
                 input_report_key(dev->input, BTN_TOUCH, 0);
                 input_report_abs(dev->input, ABS_PRESSURE, 0);
                 atp_report_fingers(dev->input, 0);
@@ -757,6 +768,10 @@ static void atp_complete_geyser_3_4(struct urb *urb)
                 memset(dev->xy_acc, 0, sizeof(dev->xy_acc));
         }
 
+        if (fingers != dev->fingers_old)
+                dev->x_old = dev->y_old = -1;
+        dev->fingers_old = fingers;
+
         input_report_key(dev->input, BTN_LEFT, key);
         input_sync(dev->input);