From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: John Steele Scott <toojays@toojays.net>
Cc: linuxppc-dev list <linuxppc-dev@lists.linuxppc.org>,
Christiaan Welvaart <cjw@daneel.dyndns.org>
Subject: Re: nearly-working support for cpufreq on 2004 iBook G4 with 7447Acpu
Date: Tue, 01 Jun 2004 12:53:50 +1000 [thread overview]
Message-ID: <1086058430.1954.3.camel@gaston> (raw)
In-Reply-To: <63605.192.43.227.18.1086055525.squirrel@www.toojays.net>
On Tue, 2004-06-01 at 12:05, John Steele Scott wrote:
> > Oh, and when switching to high speed, think about tweaking the
> > voltage too. I don't know if it's high or low when setting the
> > GPIO bit, you may want to check out OF code, it certainly have
> > methods for that. Or you can read the voltage value back from
> > the adt themometer chip I think, as it does voltage control.
>
> I will double-check this tonight (am at uni now), but I thought that the
> core voltage for this chip does not change with frequency . . . :(
It probably does since there is a GPIO for controlling it on
KeyLargo. It's not the chip itself that changes it, you use the GPIO
to change it before/after the freq. switch. That's wher the real saving
comes from, more than the freq change itself in fact.
ben.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2004-06-01 2:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-30 14:01 nearly-working support for cpufreq on 2004 iBook G4 with 7447A cpu John Steele Scott
2004-05-30 22:43 ` Benjamin Herrenschmidt
2004-05-30 22:43 ` Benjamin Herrenschmidt
2004-05-31 0:32 ` John Steele Scott
2004-05-31 0:29 ` Benjamin Herrenschmidt
2004-05-31 3:49 ` Benjamin Herrenschmidt
2004-05-31 8:37 ` John Steele Scott
2004-05-31 23:41 ` Benjamin Herrenschmidt
2004-05-31 23:47 ` Benjamin Herrenschmidt
2004-06-01 2:05 ` nearly-working support for cpufreq on 2004 iBook G4 with 7447Acpu John Steele Scott
2004-06-01 2:53 ` Benjamin Herrenschmidt [this message]
2004-06-02 11:08 ` nearly-working support for cpufreq on 2004 iBook G4 with 7447A cpu John Steele Scott
2004-06-03 22:26 ` Benjamin Herrenschmidt
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