From: Josh Boyer <jwboyer@linux.vnet.ibm.com>
To: Scott Wood <scottwood@freescale.com>
Cc: "Leisner, Martin" <Martin.Leisner@xerox.com>,
linuxppc-embedded@ozlabs.org
Subject: Re: finding out the processor frequency
Date: Thu, 6 Sep 2007 14:15:05 -0500 [thread overview]
Message-ID: <20070906141505.18bd399a@zod.rchland.ibm.com> (raw)
In-Reply-To: <20070906184308.GA22380@ld0162-tx32.am.freescale.net>
On Thu, 6 Sep 2007 13:43:08 -0500
Scott Wood <scottwood@freescale.com> wrote:
> On Thu, Sep 06, 2007 at 02:24:30PM -0400, Leisner, Martin wrote:
> > What exactly do we mean by "timebase"?
> >
> > There a symbol in arch/powerpc/time.c:ppc_proc_freq which looks like the
> > processor frequency (derived from the dts). But its not exported.
> >
> > There's also ppc_tb_freq.
>
> The timebase is the rate at which the timebase and decrementer registers
> tick. It is not the same as the CPU core frequency.
Unless your timebase and decrementer clock source is tied to the CPU
clock. :)
So it depends on the board, and it can even depend on how the board is
initialized. Some boards can change the timebase clock source on the
fly.
josh
next prev parent reply other threads:[~2007-09-06 19:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-06 18:24 finding out the processor frequency Leisner, Martin
2007-09-06 18:43 ` Scott Wood
2007-09-06 19:15 ` Josh Boyer [this message]
2007-09-06 19:15 ` PCI target implementation on AMCC PPC CPUs Leonid
2007-09-06 20:15 ` David Hawkins
2007-09-06 23:30 ` Wolfgang Denk
2007-09-06 23:39 ` David Hawkins
2007-09-06 20:26 ` David Hawkins
2007-09-11 9:13 ` Matthias Fuchs
2007-09-11 17:32 ` David Hawkins
2007-09-11 18:17 ` David Hawkins
2007-09-12 7:17 ` Matthias Fuchs
2007-09-12 16:04 ` David Hawkins
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