linux-kernel - Re: [RFC][PATCH 3/3] Try to convert non-trivial clocksources to clocksource_register

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Date:	Mon, 10 May 2010 12:19:10 -0700
From:	john stultz <johnstul@...ibm.com>
To:	Martin Schwidefsky <schwidefsky@...ibm.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	Jim Cromie <jim.cromie@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC][PATCH 3/3] Try to convert non-trivial clocksources to
 clocksource_register_hz

On Mon, 2010-05-10 at 17:53 +0200, Martin Schwidefsky wrote:
> On Fri, 30 Apr 2010 18:36:25 -0700
> John Stultz <johnstul@...ibm.com> wrote:
> 
> > NOT FOR INCLUSION!
> > NOT FOR INCLUSION!
> > 
> > I've already gone through and converted the rest of the clocksources 
> > to use clocksource_register_hz, and I'll be hopefully pushing those 
> > to arch maintainers for 2.6.36-2.6.37.
> > 
> > However, in going through all the clocksources, I hit a few
> > non-trivial conversions and wanted to bring them up on the list
> > early so they can be handled soon.
> > 
> > The following patch tries to convert the non-trival clocksources
> > to use clocksource_register_hz/khz. It is likely broken. I will
> > need arch maintainer help to figure out the best way to resovle 
> > these clocksources.
> > 
> > This patch requires the previous "Add clocksource_register_hz/khz 
> > interface" patch to build. 
> > 
> > So any help maintainers can provide in finding solutions to
> > break the mult/shift assumptions in the arch code would be
> > greatly appreciated!
> > 
> > thanks
> > -john
> > 
> > NOT FOR INCLUSION!
> > NOT FOR INCLUSION!
> 
> The s390 conversion to clocksource_register_khz looks good - at least
> the kilo hertz value is correct. Bit 2^12 of the TOD value are
> microseconds, which makes one millisecond (1000<<12). 

Thanks for the review!

However, is there a more straightforward frequency value that we could
use? Is 4096000000 hz really the correct value or is there something
more precise?

thanks again!
-john




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