Input: synaptics - refactor y inversion

Synaptics touchpads report increasing y from bottom to top.
This is inverted from normal userspace "top of screen is 0" coordinates.
Thus, the kernel driver reports inverted y coordinates to userspace.

This patch refactors this inversion.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Acked-by: Chase Douglas <chase.douglas@canonical.com>
Acked-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 12 insertions, 3 deletions

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 5538fc657af1..b0008bcb26fc 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -44,6 +44,16 @@
 #define YMIN_NOMINAL 1408
 #define YMAX_NOMINAL 4448
 
+/*
+ * Synaptics touchpads report the y coordinate from bottom to top, which is
+ * opposite from what userspace expects.
+ * This function is used to invert y before reporting.
+ */
+static int synaptics_invert_y(int y)
+{
+        return YMAX_NOMINAL + YMIN_NOMINAL - y;
+}
+
 
 /*****************************************************************************
  *      Stuff we need even when we do not want native Synaptics support
@@ -502,8 +512,7 @@ static void synaptics_report_semi_mt_slot(struct input_dev *dev, int slot,
         input_mt_report_slot_state(dev, MT_TOOL_FINGER, active);
         if (active) {
                 input_report_abs(dev, ABS_MT_POSITION_X, x);
-                input_report_abs(dev, ABS_MT_POSITION_Y,
-                                 YMAX_NOMINAL + YMIN_NOMINAL - y);
+                input_report_abs(dev, ABS_MT_POSITION_Y, synaptics_invert_y(y));
         }
 }
 
@@ -597,7 +606,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
 
         if (num_fingers > 0) {
                 input_report_abs(dev, ABS_X, hw.x);
-                input_report_abs(dev, ABS_Y, YMAX_NOMINAL + YMIN_NOMINAL - hw.y);
+                input_report_abs(dev, ABS_Y, synaptics_invert_y(hw.y));
         }
         input_report_abs(dev, ABS_PRESSURE, hw.z);