Input: appletouch - fix integer overflow issue
When reading data from Geyser 2 touchpads used on post Oct 2005 Apple
PowerBooks the driver was casting X and Y coordinates values to
'signed char'. Testing on one of such PowerBooks I have noticed that
touchpad always generates positive values, but some of them are greater
that 127, and thus, when cast to 'signed char' being interpreted as
a negative.
Such bigger values have been observed infrequently, closer to the
edges of a touchpad, so the problem was not very visible.
Nevertheless, the patch would potentially improve touchpad
driver accuracy.
Signed-off-by: Vadim Zaliva <lord@crocodile.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/mouse/appletouch.c b/drivers/input/mouse/appletouch.c
index 908b5b4..53ec7dd 100644
--- a/drivers/input/mouse/appletouch.c
+++ b/drivers/input/mouse/appletouch.c
@@ -205,8 +205,8 @@
bool overflow_warned;
int x_old; /* last reported x/y, */
int y_old; /* used for smoothing */
- signed char xy_cur[ATP_XSENSORS + ATP_YSENSORS];
- signed char xy_old[ATP_XSENSORS + ATP_YSENSORS];
+ u8 xy_cur[ATP_XSENSORS + ATP_YSENSORS];
+ u8 xy_old[ATP_XSENSORS + ATP_YSENSORS];
int xy_acc[ATP_XSENSORS + ATP_YSENSORS];
int idlecount; /* number of empty packets */
struct work_struct work;
@@ -531,7 +531,7 @@
for (i = 0; i < ATP_XSENSORS + ATP_YSENSORS; i++) {
/* accumulate the change */
- signed char change = dev->xy_old[i] - dev->xy_cur[i];
+ int change = dev->xy_old[i] - dev->xy_cur[i];
dev->xy_acc[i] -= change;
/* prevent down drifting */