Input: psmouse - ensure that focaltech reports consistent coordinates
authorMathias Gottschlag <mgottschlag@gmail.com>
Sat, 7 Mar 2015 21:27:08 +0000 (13:27 -0800)
committerDmitry Torokhov <dmitry.torokhov@gmail.com>
Sat, 7 Mar 2015 21:40:20 +0000 (13:40 -0800)
We don't know whether x_max or y_max really hold the maximum possible
coordinates, and we don't know for sure whether we correctly interpret the
coordinates sent by the touchpad, so we clamp the reported values to
prevent confusion in userspace code.

Signed-off-by: Mathias Gottschlag <mgottschlag@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
drivers/input/mouse/focaltech.c

index e8fafe8..c66e0e0 100644 (file)
@@ -126,9 +126,17 @@ static void focaltech_report_state(struct psmouse *psmouse)
                input_mt_slot(dev, i);
                input_mt_report_slot_state(dev, MT_TOOL_FINGER, active);
                if (active) {
-                       input_report_abs(dev, ABS_MT_POSITION_X, finger->x);
+                       unsigned int clamped_x, clamped_y;
+                       /*
+                        * The touchpad might report invalid data, so we clamp
+                        * the resulting values so that we do not confuse
+                        * userspace.
+                        */
+                       clamped_x = clamp(finger->x, 0U, priv->x_max);
+                       clamped_y = clamp(finger->y, 0U, priv->y_max);
+                       input_report_abs(dev, ABS_MT_POSITION_X, clamped_x);
                        input_report_abs(dev, ABS_MT_POSITION_Y,
-                                        priv->y_max - finger->y);
+                                        priv->y_max - clamped_y);
                }
        }
        input_mt_report_pointer_emulation(dev, true);