#define ATP_GEYSER_MODE_REQUEST_INDEX          0
 #define ATP_GEYSER_MODE_VENDOR_VALUE           0x04
 
+/**
+ * enum atp_status_bits - status bit meanings
+ *
+ * These constants represent the meaning of the status bits.
+ * (only Geyser 3/4)
+ *
+ * @ATP_STATUS_BUTTON: The button was pressed
+ * @ATP_STATUS_BASE_UPDATE: Update of the base values (untouched pad)
+ * @ATP_STATUS_FROM_RESET: Reset previously performed
+ */
+enum atp_status_bits {
+       ATP_STATUS_BUTTON       = BIT(0),
+       ATP_STATUS_BASE_UPDATE  = BIT(2),
+       ATP_STATUS_FROM_RESET   = BIT(4),
+};
+
 /* Structure to hold all of our device specific stuff */
 struct atp {
        char                    phys[64];
        struct usb_device       *udev;          /* usb device */
        struct urb              *urb;           /* usb request block */
-       signed char             *data;          /* transferred data */
+       u8                      *data;          /* transferred data */
        struct input_dev        *input;         /* input dev */
        enum atp_touchpad_type  type;           /* type of touchpad */
        bool                    open;
        int retval;
 
        dprintk("appletouch: putting appletouch to sleep (reinit)\n");
-       dev->idlecount = 0;
-
        atp_geyser_init(udev);
 
        retval = usb_submit_urb(dev->urb, GFP_ATOMIC);
                              ATP_XFACT, &x_z, &x_f);
        y = atp_calculate_abs(dev->xy_acc + ATP_XSENSORS, ATP_YSENSORS,
                              ATP_YFACT, &y_z, &y_f);
-       key = dev->data[dev->datalen - 1] & 1;
+       key = dev->data[dev->datalen - 1] & ATP_STATUS_BUTTON;
 
        if (x && y) {
                if (dev->x_old != -1) {
 
        dbg_dump("sample", dev->xy_cur);
 
-       if (!dev->valid) {
-               /* first sample */
-               dev->valid = true;
-               dev->x_old = dev->y_old = -1;
-               memcpy(dev->xy_old, dev->xy_cur, sizeof(dev->xy_old));
+       /* Just update the base values (i.e. touchpad in untouched state) */
+       if (dev->data[dev->datalen - 1] & ATP_STATUS_BASE_UPDATE) {
 
+               dprintk(KERN_DEBUG "appletouch: updated base values\n");
+
+               memcpy(dev->xy_old, dev->xy_cur, sizeof(dev->xy_old));
                goto exit;
        }
 
        for (i = 0; i < ATP_XSENSORS + ATP_YSENSORS; i++) {
-               /* accumulate the change */
-               signed char change = dev->xy_old[i] - dev->xy_cur[i];
-               dev->xy_acc[i] -= change;
+               /* calculate the change */
+               dev->xy_acc[i] = dev->xy_cur[i] - dev->xy_old[i];
+
+               /* this is a round-robin value, so couple with that */
+               if (dev->xy_acc[i] > 127)
+                       dev->xy_acc[i] -= 256;
+
+               if (dev->xy_acc[i] < -127)
+                       dev->xy_acc[i] += 256;
 
                /* prevent down drifting */
                if (dev->xy_acc[i] < 0)
                        dev->xy_acc[i] = 0;
        }
 
-       memcpy(dev->xy_old, dev->xy_cur, sizeof(dev->xy_old));
-
        dbg_dump("accumulator", dev->xy_acc);
 
        x = atp_calculate_abs(dev->xy_acc, ATP_XSENSORS,
                              ATP_XFACT, &x_z, &x_f);
        y = atp_calculate_abs(dev->xy_acc + ATP_XSENSORS, ATP_YSENSORS,
                              ATP_YFACT, &y_z, &y_f);
-       key = dev->data[dev->datalen - 1] & 1;
+       key = dev->data[dev->datalen - 1] & ATP_STATUS_BUTTON;
 
        if (x && y) {
                if (dev->x_old != -1) {
        if (!x && !y && !key) {
                dev->idlecount++;
                if (dev->idlecount == 10) {
-                       dev->valid = false;
+                       dev->x_old = dev->y_old = -1;
+                       dev->idlecount = 0;
                        schedule_work(&dev->work);
                        /* Don't resubmit urb here, wait for reinit */
                        return;
        struct atp *dev = usb_get_intfdata(iface);
 
        usb_kill_urb(dev->urb);
-       dev->valid = false;
-
        return 0;
 }