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RE: [PATCH] TX4927 processor can support different speeds

To: "'Maciej W. Rozycki'" <macro@linux-mips.org>, Manish Lachwani <mlachwani@mvista.com>
Subject: RE: [PATCH] TX4927 processor can support different speeds
From: Brad Larson <Brad_Larson@pmc-sierra.com>
Date: Mon, 24 Jan 2005 13:23:13 -0800
Cc: Ralf Baechle <ralf@linux-mips.org>, Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>, linux-mips@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
> On Mon, 24 Jan 2005, Manish Lachwani wrote:
> 
> > > > Why is this approach (in the patch) bad?
> [...]
> > > It's fragile because clock frequencies are changing 
> faster in today's
> > > world of electronics than the weather in April.
> [...]
> > So? Can you be a little more clear?
> 
>  Oh well, how can you assure a given binary will be booted on 
> a CPU driven 
> by the right frequency?  Is the clock source inside the chip 
> containing 
> the CPU at least?
> 
>   Maciej

I've seen more boards with slightly, sometimes dramatically, modified cpu clock 
source for performance and production reliability reasons than not having an 
external RTC.  External RTC present and one kernel can accurately enough report 
the cpu frequency for Toshiba "stock" values and others as well.

--Brad

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