From: David Howells <dhowells@redhat.com>
In-Reply-To: <20041102123509.GA8259@dominikbrodowski.de> 
References: <20041102123509.GA8259@dominikbrodowski.de> 
To: Dominik Brodowski <linux@dominikbrodowski.de>
Cc: cpufreq@www.linux.org.uk, davej@redhat.com, linux-kernel@vger.kernel.org,
       uclinux-dev@uclinux.org
Subject: Re: FRV and CPU frequency scaling 
User-Agent: EMH/1.14.1 SEMI/1.14.5 (Awara-Onsen) FLIM/1.14.5 (Demachiyanagi) APEL/10.6 Emacs/21.3 (i386-redhat-linux-gnu) MULE/5.0 (SAKAKI)
MIME-Version: 1.0 (generated by SEMI 1.14.5 - "Awara-Onsen")
Content-Type: text/plain; charset=US-ASCII
Date: Tue, 02 Nov 2004 13:35:37 +0000
Message-ID: <14027.1099402537@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1221
Lines: 32


> While reading through the FRV Documentation patch I stumbled across the file
> "clock.txt" file which says:
> 
> + (*) clock.txt
> +
> +     A description of the CPU clock scaling interface.
> +
> 
> Could you use the generic cpufreq core (drivers/cpufreq/) for this, please?

Maybe. I'm not sure how simple it will be to adapt, since there are several
"clocks", and the setting changes the ratios between them.

> And could you explain the difference between p0, cm and cmode settings to
> me, and how they can be combined, please? Or is the following assumption 
> correct?
> 
> The CPU core frequency can only be modified on FR405 CPUs, while p0 and cm 
> are available on all CPUs and allow for modification of the frequency of 
> some sort of external busses.

It's quite complicated. There are 16 clock ratio mode settings, a bus speed
doubler and a raw clock speed indicator. The mode table varies from CPU to
CPU, and not all modes are available on all CPUs.

David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/