1 files changed, 211 insertions, 9 deletions

diff --git a/drivers/hid/hid-ntrig.c b/drivers/hid/hid-ntrig.c
index 4777bbfa1cc2..227d01527c6a 100644
--- a/drivers/hid/hid-ntrig.c
+++ b/drivers/hid/hid-ntrig.c
@@ -24,6 +24,13 @@
 
 #define NTRIG_DUPLICATE_USAGES  0x001
 
+static unsigned int min_width;
+static unsigned int min_height;
+static unsigned int activate_slack = 1;
+static unsigned int deactivate_slack = 4;
+static unsigned int activation_width = 64;
+static unsigned int activation_height = 32;
+
 struct ntrig_data {
         /* Incoming raw values for a single contact */
         __u16 x, y, w, h;
@@ -37,6 +44,28 @@ struct ntrig_data {
 
         __u8 mt_footer[4];
         __u8 mt_foot_count;
+
+        /* The current activation state. */
+        __s8 act_state;
+
+        /* Empty frames to ignore before recognizing the end of activity */
+        __s8 deactivate_slack;
+
+        /* Frames to ignore before acknowledging the start of activity */
+        __s8 activate_slack;
+
+        /* Minimum size contact to accept */
+        __u16 min_width;
+        __u16 min_height;
+
+        /* Threshold to override activation slack */
+        __u16 activation_width;
+        __u16 activation_height;
+
+        __u16 sensor_logical_width;
+        __u16 sensor_logical_height;
+        __u16 sensor_physical_width;
+        __u16 sensor_physical_height;
 };
 
 /*
@@ -49,6 +78,8 @@ static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                 struct hid_field *field, struct hid_usage *usage,
                 unsigned long **bit, int *max)
 {
+        struct ntrig_data *nd = hid_get_drvdata(hdev);
+
         /* No special mappings needed for the pen and single touch */
         if (field->physical)
                 return 0;
@@ -62,6 +93,21 @@ static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                         input_set_abs_params(hi->input, ABS_X,
                                         field->logical_minimum,
                                         field->logical_maximum, 0, 0);
+
+                        if (!nd->sensor_logical_width) {
+                                nd->sensor_logical_width =
+                                        field->logical_maximum -
+                                        field->logical_minimum;
+                                nd->sensor_physical_width =
+                                        field->physical_maximum -
+                                        field->physical_minimum;
+                                nd->activation_width = activation_width *
+                                        nd->sensor_logical_width /
+                                        nd->sensor_physical_width;
+                                nd->min_width = min_width *
+                                        nd->sensor_logical_width /
+                                        nd->sensor_physical_width;
+                        }
                         return 1;
                 case HID_GD_Y:
                         hid_map_usage(hi, usage, bit, max,
@@ -69,6 +115,21 @@ static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                         input_set_abs_params(hi->input, ABS_Y,
                                         field->logical_minimum,
                                         field->logical_maximum, 0, 0);
+
+                        if (!nd->sensor_logical_height) {
+                                nd->sensor_logical_height =
+                                        field->logical_maximum -
+                                        field->logical_minimum;
+                                nd->sensor_physical_height =
+                                        field->physical_maximum -
+                                        field->physical_minimum;
+                                nd->activation_height = activation_height *
+                                        nd->sensor_logical_height /
+                                        nd->sensor_physical_height;
+                                nd->min_height = min_height *
+                                        nd->sensor_logical_height /
+                                        nd->sensor_physical_height;
+                        }
                         return 1;
                 }
                 return 0;
@@ -201,20 +262,68 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                         if (nd->mt_foot_count != 4)
                                 break;
 
-                        /* Pen activity signal, trigger end of touch. */
+                        /* Pen activity signal. */
                         if (nd->mt_footer[2]) {
+                                /*
+                                 * When the pen deactivates touch, we see a
+                                 * bogus frame with ContactCount > 0.
+                                 * We can
+                                 * save a bit of work by ensuring act_state < 0
+                                 * even if deactivation slack is turned off.
+                                 */
+                                nd->act_state = deactivate_slack - 1;
                                 nd->confidence = 0;
                                 break;
                         }
 
-                        /* If the contact was invalid */
-                        if (!(nd->confidence && nd->mt_footer[0])
-                                        || nd->w <= 250
-                                        || nd->h <= 190) {
-                                nd->confidence = 0;
+                        /*
+                         * The first footer value indicates the presence of a
+                         * finger.
+                         */
+                        if (nd->mt_footer[0]) {
+                                /*
+                                 * We do not want to process contacts under
+                                 * the size threshold, but do not want to
+                                 * ignore them for activation state
+                                 */
+                                if (nd->w < nd->min_width ||
+                                    nd->h < nd->min_height)
+                                        nd->confidence = 0;
+                        } else
                                 break;
+
+                        if (nd->act_state > 0) {
+                                /*
+                                 * Contact meets the activation size threshold
+                                 */
+                                if (nd->w >= nd->activation_width &&
+                                    nd->h >= nd->activation_height) {
+                                        if (nd->id)
+                                                /*
+                                                 * first contact, activate now
+                                                 */
+                                                nd->act_state = 0;
+                                        else {
+                                                /*
+                                                 * avoid corrupting this frame
+                                                 * but ensure next frame will
+                                                 * be active
+                                                 */
+                                                nd->act_state = 1;
+                                                break;
+                                        }
+                                } else
+                                        /*
+                                         * Defer adjusting the activation state
+                                         * until the end of the frame.
+                                         */
+                                        break;
                         }
 
+                        /* Discarding this contact */
+                        if (!nd->confidence)
+                                break;
+
                         /* emit a normal (X, Y) for the first point only */
                         if (nd->id == 0) {
                                 /*
@@ -227,8 +336,15 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                                 input_event(input, EV_ABS, ABS_X, nd->x);
                                 input_event(input, EV_ABS, ABS_Y, nd->y);
                         }
+
+                        /* Emit MT events */
                         input_event(input, EV_ABS, ABS_MT_POSITION_X, nd->x);
                         input_event(input, EV_ABS, ABS_MT_POSITION_Y, nd->y);
+
+                        /*
+                         * Translate from height and width to size
+                         * and orientation.
+                         */
                         if (nd->w > nd->h) {
                                 input_event(input, EV_ABS,
                                                 ABS_MT_ORIENTATION, 1);
@@ -248,12 +364,88 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                         break;
 
                 case HID_DG_CONTACTCOUNT: /* End of a multitouch group */
-                        if (!nd->reading_mt)
+                        if (!nd->reading_mt) /* Just to be sure */
                                 break;
 
                         nd->reading_mt = 0;
 
-                        if (nd->first_contact_touch) {
+
+                        /*
+                         * Activation state machine logic:
+                         *
+                         * Fundamental states:
+                         *      state >  0: Inactive
+                         *      state <= 0: Active
+                         *      state <  -deactivate_slack:
+                         *               Pen termination of touch
+                         *
+                         * Specific values of interest
+                         *      state == activate_slack
+                         *               no valid input since the last reset
+                         *
+                         *      state == 0
+                         *               general operational state
+                         *
+                         *      state == -deactivate_slack
+                         *               read sufficient empty frames to accept
+                         *               the end of input and reset
+                         */
+
+                        if (nd->act_state > 0) { /* Currently inactive */
+                                if (value)
+                                        /*
+                                         * Consider each live contact as
+                                         * evidence of intentional activity.
+                                         */
+                                        nd->act_state = (nd->act_state > value)
+                                                        ? nd->act_state - value
+                                                        : 0;
+                                else
+                                        /*
+                                         * Empty frame before we hit the
+                                         * activity threshold, reset.
+                                         */
+                                        nd->act_state = nd->activate_slack;
+
+                                /*
+                                 * Entered this block inactive and no
+                                 * coordinates sent this frame, so hold off
+                                 * on button state.
+                                 */
+                                break;
+                        } else { /* Currently active */
+                                if (value && nd->act_state >=
+                                             nd->deactivate_slack)
+                                        /*
+                                         * Live point: clear accumulated
+                                         * deactivation count.
+                                         */
+                                        nd->act_state = 0;
+                                else if (nd->act_state <= nd->deactivate_slack)
+                                        /*
+                                         * We've consumed the deactivation
+                                         * slack, time to deactivate and reset.
+                                         */
+                                        nd->act_state =
+                                                nd->activate_slack;
+                                else { /* Move towards deactivation */
+                                        nd->act_state--;
+                                        break;
+                                }
+                        }
+
+                        if (nd->first_contact_touch && nd->act_state <= 0) {
+                                /*
+                                 * Check to see if we're ready to start
+                                 * emitting touch events.
+                                 *
+                                 * Note: activation slack will decrease over
+                                 * the course of the frame, and it will be
+                                 * inconsistent from the start to the end of
+                                 * the frame.  However if the frame starts
+                                 * with slack, first_contact_touch will still
+                                 * be 0 and we will not get to this point.
+                                 */
                                 input_report_key(input, BTN_TOOL_DOUBLETAP, 1);
                                 input_report_key(input, BTN_TOUCH, 1);
                         } else {
@@ -263,7 +455,7 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                         break;
 
                 default:
-                        /* fallback to the generic hidinput handling */
+                        /* fall-back to the generic hidinput handling */
                         return 0;
                 }
         }
@@ -293,6 +485,16 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
         }
 
         nd->reading_mt = 0;
+        nd->min_width = 0;
+        nd->min_height = 0;
+        nd->activate_slack = activate_slack;
+        nd->act_state = activate_slack;
+        nd->deactivate_slack = -deactivate_slack;
+        nd->sensor_logical_width = 0;
+        nd->sensor_logical_height = 0;
+        nd->sensor_physical_width = 0;
+        nd->sensor_physical_height = 0;
+
         hid_set_drvdata(hdev, nd);
 
         ret = hid_parse(hdev);