From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: Joe Perches <joe@perches.com>
Cc: Mischa Jonker <Mischa.Jonker@synopsys.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Joern Rennecke <joern.rennecke@embecosm.com>
Subject: Re: [PATCH] ARC: Fix __udelay parentheses
Date: Thu, 29 Aug 2013 06:49:07 +0000 [thread overview]
Message-ID: <C2D7FE5348E1B147BCA15975FBA23075140F85@IN01WEMBXA.internal.synopsys.com> (raw)
In-Reply-To: <1377758224.1928.91.camel@joe-AO722>
On 08/29/2013 12:07 PM, Joe Perches wrote:
>> On the topic of multiply vs. divide (which probably is not relevant to topic at
>> hand though), since ARCompact doesn't have native divide, we end up emulating it
>> using libgcc routines. That makes it slightly non-deterministic (not a big deal)
>> and also adds to boot time (which those delays sprinkled all over the place in
>> crazy device probes and such). Seriously we got hammered by a customer for that once.
> That argues more for reducing the uses of hard delays
> than making the hard delay count calculation simpler.
Right, but most often the drivers are written/maintained by non arch people.
I'm with you in terms of simplification and I think the following
loops = ((u64)usecs * 4295 * HZ * loops_per_jiffy) >> 32;
is fairly simple, well commented, and optimal for ARC.
-Vineet
prev parent reply other threads:[~2013-08-29 6:49 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
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 [this message]
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