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Subject[PATCH] driver/input/ff-memless.c
I was experiencing force feedback joystick issues in my Force 3D Pro and
when developing a new driver for the new Logitech G940 after I
recompiled my kernel.

I was able to track it down to a signed vs unsigned problem in
ff-memless.c and gcc 4.4.2.
The code in question did not seem to give a problem with gcc 4.2.4.

According to gitweb, a signed vs unsigned was changed on May 8th by
Jussi Kivilinna <>
Input: ff-memless - fix signed to unsigned bit overflow

to change the gain from a signed to an unsigned int to fix a rumble
issue, but it appears to broke a the
constant force section of the code.

It is a simple, cast to fix and should not have any ill effects.


--- linux-2.6.31.orig/drivers/input/ff-memless.c 2009-09-09
17:13:59.000000000 -0500
+++ 2009-12-07
15:09:22.000000000 -0500
@@ -239,8 +239,8 @@
level = fixp_new16(apply_envelope(state,
- x = fixp_mult(fixp_sin(i), level) * gain / 0xffff;
- y = fixp_mult(-fixp_cos(i), level) * gain / 0xffff;
+ x = (int)(fixp_mult(fixp_sin(i), level) * gain) / 0xffff;
+ y = (int)(fixp_mult(-fixp_cos(i), level) * gain) / 0xffff;
* here we abuse ff_ramp to hold x and y of constant force
* If in future any driver wants something else than x and y

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