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SubjectRe: [PATCH] driver/input/ff-memless.c
Hi Gary,

On Mon, Dec 07, 2009 at 02:37:30PM -0500, Gary Stein wrote:
> 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.
>

Could I please have your "Signed-off-by: ..."? Thanks.

> 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

--
Dmitry


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