Input: alps - process_bitmap: round down when spreading adjescent fingers over 2 points

This fixes 2 fingers at the same height or width on the touchpad getting
reported at different y / x coordinates.

Note num_bits is always at least 1.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index 5b35f4fc4d2f..1c9917828956 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -391,13 +391,13 @@ static int alps_process_bitmap(struct alps_data *priv,
          * adjacent fingers. Divide the single contact between the two points.
          */
         if (fingers_x == 1) {
-                i = x_low.num_bits / 2;
+                i = (x_low.num_bits - 1) / 2;
                 x_low.num_bits = x_low.num_bits - i;
                 x_high.start_bit = x_low.start_bit + i;
                 x_high.num_bits = max(i, 1);
         }
         if (fingers_y == 1) {
-                i = y_low.num_bits / 2;
+                i = (y_low.num_bits - 1) / 2;
                 y_low.num_bits = y_low.num_bits - i;
                 y_high.start_bit = y_low.start_bit + i;
                 y_high.num_bits = max(i, 1);