drivers/input/ft5x06.c: Fix a problem was was causing missing reports when the touch ends.

configs/lpcxpresso-lpc54628/README.txt

@@ -68,14 +68,10 @@ STATUS
     based poll instead of interrupts.  This is very inefficient in that it
     will introduce delays in touchscreen response and will consume more CPU
     bandwidth.  The driver appears to be functional.  Added the nxwm
-    configuration to do some integrated testing.  It does not yet work and
+    configuration to do some integrated testing.  NxWM seems to be fully
-    I have not yet looked into the cause of the problem:
+    functional.  However, the action of the touchscreen could use some
-
+    human factors improvements.  I imagine that this is a consequence of
-      Initialize the NSH library
+    the polled solution.
-      createTaskbar: Create CTaskbar instance
-      createTaskbar: Connect CTaskbar instance to the NX server
-      createTaskbar: ERROR: Failed to connect CTaskbar instance to the NX server
-      nxwm_main: ERROR: Failed to create the task bar
 
 Configurations
 ==============

drivers/input/ft5x06.c

@@ -212,7 +212,7 @@ static const struct file_operations ft5x06_fops =
 static const uint8_t g_event_map[4] =
 {
   (TOUCH_DOWN | TOUCH_ID_VALID | TOUCH_POS_VALID), /* FT5x06_DOWN */
-  (TOUCH_UP   | TOUCH_ID_VALID | TOUCH_POS_VALID), /* FT5x06_UP */
+  (TOUCH_UP   | TOUCH_ID_VALID),                   /* FT5x06_UP */
   (TOUCH_MOVE | TOUCH_ID_VALID | TOUCH_POS_VALID), /* FT5x06_CONTACT */
   TOUCH_ID_VALID                                   /* FT5x06_INVALID */
 };
@@ -321,7 +321,9 @@ static void ft5x06_data_worker(FAR void *arg)
   if (ret >= 0)
     {
       /* In polled mode, we may read invalid touch data.  If there is
-       * no touch data, the FT5x06 returns all 0xff.
+       * no touch data, the FT5x06 returns all 0xff the very first time.
+       * After that, it returns the same old stale data when there is
+       * no touch data.
        */
 
       sample = (FAR struct ft5x06_touch_data_s *)priv->touchbuf;
@@ -347,7 +349,9 @@ static void ft5x06_data_worker(FAR void *arg)
         }
       else if (priv->delay < POLL_MAXDELAY)
         {
-          /* Let it rise gradually to the maximum if there is no touch */
+          /* Otherwise, let the poll rate rise gradually up to the maximum
+           * if there is no touch.
+           */
 
           priv->delay += POLL_INCREMENT;
         }
@@ -467,17 +471,10 @@ static ssize_t ft5x06_sample(FAR struct ft5x06_dev_s *priv, FAR char *buffer,
   /* Raw data pointers (source) */
 
   raw = (FAR struct ft5x06_touch_data_s *)priv->touchbuf;
-
+  touch = raw->touch;
-  if (raw->tdstatus != 1)
-    {
-      priv->valid = false;
-      return 0;  /* No touches read. */
-    }
 
   /* Get the reported X and Y positions */
 
-  touch = raw->touch;
-
   #ifdef CONFIG_FT5X06_SWAPXY
   y = TOUCH_POINT_GET_X(touch[0]);
   x = TOUCH_POINT_GET_Y(touch[0]);
@@ -491,14 +488,28 @@ static ssize_t ft5x06_sample(FAR struct ft5x06_dev_s *priv, FAR char *buffer,
   event = TOUCH_POINT_GET_EVENT(touch[0]);
   id    = TOUCH_POINT_GET_ID(touch[0]);
 
+  if (event == FT5x06_INVALID)
+    {
+      priv->lastevent = FT5x06_INVALID;
+      goto drop;
+    }
+
   if (id == priv->lastid && event == priv->lastevent)
+    {
+      /* Same ID and event..  Is there positional data? */
+
+      if (raw->tdstatus == 0 || event == FT5x06_UP)
+        {
+          /* No... no new touch data */
+
+          goto drop;
+        }
+      else
         {
           int16_t deltax;
           int16_t deltay;
 
-      /* Same ID and event.. Compare the change in position from the last
+          /* Compare the change in position from the last report. */
-       * report.
-       */
 
           deltax = (x - priv->lastx);
           if (deltax < 0)
@@ -520,8 +531,8 @@ static ssize_t ft5x06_sample(FAR struct ft5x06_dev_s *priv, FAR char *buffer,
                 {
                   /* Ignore... no significant change in Y either */
 
-              priv->valid = false;
+                  goto drop;
-              return 0;  /* No new touches read. */
+                }
             }
         }
     }
@@ -551,6 +562,12 @@ static ssize_t ft5x06_sample(FAR struct ft5x06_dev_s *priv, FAR char *buffer,
 
   priv->valid       = false;
   return SIZEOF_TOUCH_SAMPLE_S(1);
+
+drop:
+  priv->lastx = 0;
+  priv->lasty = 0;
+  priv->valid = false;
+  return 0;  /* No new touches read. */
 }
 #else
 static ssize_t ft5x06_sample(FAR struct ft5x06_dev_s *priv, FAR char *buffer,