Messages in this thread Patch in this message | | | Date | Mon, 7 Dec 2009 14:37:30 -0500 | Subject | [PATCH] driver/input/ff-memless.c | From | Gary Stein <> |
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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 <jussi.kivilinna@mbnet.fi> 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.
gary
--- linux-2.6.31.orig/drivers/input/ff-memless.c 2009-09-09 17:13:59.000000000 -0500 +++ linux-2.6.31.int/drivers/input/ff-memless.c 2009-12-07 15:09:22.000000000 -0500 @@ -239,8 +239,8 @@ level = fixp_new16(apply_envelope(state, new->u.constant.level, &new->u.constant.envelope)); - 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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