From: Mischa Jonker <Mischa.Jonker@synopsys.com>
To: Joe Perches <joe@perches.com>,
Mischa Jonker <Mischa.Jonker@synopsys.com>
Cc: "Vineet.Gupta1@synopsys.com" <Vineet.Gupta1@synopsys.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] ARC: Fix __udelay parentheses
Date: Wed, 28 Aug 2013 19:12:22 +0000 [thread overview]
Message-ID: <E6BF041E97966E4DB955F0DF883AD2D684F1F648@de02wembxa.internal.synopsys.com> (raw)
In-Reply-To: <1377716507.1928.57.camel@joe-AO722>
Hello Joe,
> I don't see the loops_per_jiffy initial shift << 32.
loops_per_jiffy * HZ = loops_per_second
loops_per_jiffy * HZ = 1,000,000 * loops_per_us
loops_per_jiffy * HZ * 4295 = 4,295,000 * loops_per_us
loops_per_jiffy * HZ * 4294.967296 = 2^32 * loops_per_us
> > > > - loops = ((long long)(usecs * 4295 * HZ) *
> > > > - (long long)(loops_per_jiffy)) >> 32;
> > > > + loops = (((long long) usecs) * 4295 * HZ *
> > > > + (long long) loops_per_jiffy) >> 32;
>
> I know that. It's the use of a signed long long vs the unsigned long long
> that I think wrong.
Yes that is wrong too.
>
> Why cast a unsigned to a signed?
I don't know, this was in the original file. The issue that I was trying to solve, was that usleep didn't sleep long enough, and that is fixed by this patch.
Wrt signed/unsigned: would you like me to update this patch or create a separate one?
Mischa
next prev parent reply other threads:[~2013-08-28 19:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-28 18:29 Mischa Jonker
2013-08-28 18:45 ` Joe Perches
2013-08-28 18:53 ` Mischa Jonker
2013-08-28 19:01 ` Joe Perches
2013-08-28 19:12 ` Mischa Jonker [this message]
2013-08-29 1:43 ` Joe Perches
2013-08-29 5:55 ` Vineet Gupta
2013-08-29 6:01 ` Joe Perches
2013-08-29 6:24 ` Vineet Gupta
2013-08-29 6:37 ` Joe Perches
2013-08-29 6:49 ` Vineet Gupta
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