[PATCH synaptics] Use ABS_MT events for the palm detection when supported

[Gabriele Mazzotta]

Use ABS_MT_TOUCH_MAJOR and ABS_MT_PRESSURE instead of ABS_TOOL_WIDTH
and ABS_PRESSURE when supported so that the pressure and the width of
all the fingers is taken into account for the palm detection.

This also fixes the palm detection for those touchpads for which the
kernel only sends ABS_MT_TOUCH_MAJOR and not ABS_TOOL_WIDTH.

Signed-off-by: Gabriele Mazzotta <gabriele.mzt at gmail.com>
---
I didn't modify the existing code of the palm detection to handle
multiple fingers. Relying on just the pressure and the width
thresholds to detect palms proved to be enough, so I opted for a
a quick solution that doesn't require major code changes.

 src/eventcomm.c | 12 ++++++++++++
 src/synaptics.c |  3 +++
 2 files changed, 15 insertions(+)

diff --git a/src/eventcomm.c b/src/eventcomm.c
index 37f16b2..5b18c44 100644
--- a/src/eventcomm.c
+++ b/src/eventcomm.c
@@ -606,6 +606,14 @@ EventProcessTouchEvent(InputInfoPtr pInfo, struct SynapticsHwState *hw,
                 hw->slot_state[slot_index] = SLOTSTATE_CLOSE;
                 proto_data->num_touches--;
             }
+
+            /* When there are no fingers on the touchpad, set width and
+             * pressure to zero as ABS_MT_TOUCH_MAJOR and ABS_MT_PRESSURE
+             * are not zero when fingers are released. */
+            if (proto_data->num_touches == 0) {
+                hw->fingerWidth = 0;
+                hw->z = 0;
+            }
         }
         else {
             ValuatorMask *mask = proto_data->last_mt_vals[slot_index];
@@ -618,6 +626,10 @@ EventProcessTouchEvent(InputInfoPtr pInfo, struct SynapticsHwState *hw,
                     hw->cumulative_dx += ev->value - last_val;
                 else if (ev->code == ABS_MT_POSITION_Y)
                     hw->cumulative_dy += ev->value - last_val;
+                else if (ev->code == ABS_MT_TOUCH_MAJOR)
+                    hw->fingerWidth = ev->value;
+                else if (ev->code == ABS_MT_PRESSURE)
+                    hw->z = ev->value;
             }
 
             valuator_mask_set(mask, map, ev->value);
diff --git a/src/synaptics.c b/src/synaptics.c
index 1b1ac64..2746565 100644
--- a/src/synaptics.c
+++ b/src/synaptics.c
@@ -1857,6 +1857,9 @@ SynapticsDetectFinger(SynapticsPrivate * priv, struct SynapticsHwState *hw)
     if ((hw->z > para->palm_min_z) && (hw->fingerWidth > para->palm_min_width))
         return FS_BLOCKED;
 
+    if (priv->has_touch)
+        return finger;
+
     if (hw->x == 0 || priv->finger_state == FS_UNTOUCHED)
         priv->avg_width = 0;
     else
-- 
2.1.0