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SubjectRe: linux-next: Tree for April 9
Hi Mauro,

On Sat, 11 Apr 2009 08:09:53 -0300 Mauro Carvalho Chehab <mchehab@infradead.org> wrote:
>
> On Fri, 10 Apr 2009 23:11:58 -0700
> Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > On Thu, 9 Apr 2009 16:33:05 +1000 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >
> > > I have created today's linux-next tree at
> > > git://git.kernel.org/pub/scm/linux/kernel/git/sfr/linux-next.git
> >
> > It has a link failure with i386 allmodconfig due to missing __divdi3.
> >
> > It's due to this statement in drivers/media/video/cx88/cx88-dsp.c's
> > int_goertzel():
> >
> > return (u32)(((s64)s_prev2*s_prev2 + (s64)s_prev*s_prev -
> > (s64)coeff*s_prev2*s_prev/32768)/N/N);
> >
> > that gem will need to be converted to use div64() or similar, please.
>
> Updated to use do_div().

Thank you. It will be included in next-20090414.

Andrew, I have included the patch below in case you need it before then.

--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

commit ec0a97d2dd33e156283dd04c37d77603cb4dbaf7
Author: Miroslav Sustek <sustmidown@centrum.cz>
Date: Mon Apr 6 20:07:04 2009 -0300

V4L/DVB (11441): cx88-dsp: fixing 64bit math

cx88-dsp: fixing 64bit math on 32bit kernels

Some gcc versions report the missing of __divdi3

Signed-off-by: Miroslav Sustek <sustmidown@centrum.cz>
[mchehab.redhat.com: CodingStyle fixes]
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/cx88/cx88-dsp.c b/drivers/media/video/cx88/cx88-dsp.c
index a78286e..3e5eaf3 100644
--- a/drivers/media/video/cx88/cx88-dsp.c
+++ b/drivers/media/video/cx88/cx88-dsp.c
@@ -22,6 +22,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/jiffies.h>
+#include <asm/div64.h>

#include "cx88.h"
#include "cx88-reg.h"
@@ -100,13 +101,25 @@ static u32 int_goertzel(s16 x[], u32 N, u32 freq)
s32 s_prev2 = 0;
s32 coeff = 2*int_cos(freq);
u32 i;
+
+ u64 tmp;
+ u32 divisor;
+
for (i = 0; i < N; i++) {
s32 s = x[i] + ((s64)coeff*s_prev/32768) - s_prev2;
s_prev2 = s_prev;
s_prev = s;
}
- return (u32)(((s64)s_prev2*s_prev2 + (s64)s_prev*s_prev -
- (s64)coeff*s_prev2*s_prev/32768)/N/N);
+
+ tmp = (s64)s_prev2 * s_prev2 + (s64)s_prev * s_prev -
+ (s64)coeff * s_prev2 * s_prev / 32768;
+
+ /* XXX: N must be low enough so that N*N fits in s32.
+ * Else we need two divisions. */
+ divisor = N * N;
+ do_div(tmp, divisor);
+
+ return (u32) tmp;
}

static u32 freq_magnitude(s16 x[], u32 N, u32 freq)

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