Interl XScale pxa cpufreq driver

Interl XScale pxa cpufreq driver

[Young-Jin Kim]

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Hi, 
I know there is no cpufreq driver which supports XScale PXA processor.
If I want to build a DVS system using the cpufreq infra on a PXA board,
how much work should I need? This work may include writing a PXA cpufreq driver, adding a module for changing 
the voltage, etc.
And, I want to know if there is a routine of changing the supply voltage in speedstep-ich for Intel Mobile Pentium 4.
In fact I cannot see well. 
Any comment will be helpful to me.
Regards,

Young-Jin Kim

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Re: Interl XScale pxa cpufreq driver

[Stefan Buettcher]

Young-Jin Kim wrote:
> Hi, 
> I know there is no cpufreq driver which supports XScale PXA processor.

There is one. You could have a look at the kernel sources
of the ARM Linux project or the Familiar distribution. I worked
on a project that involved DVS on a PXA board. At least the
frequency scaling part should be freely available. For voltage
scaling, we used a proprietary driver. The only problem I
encountered was some instability of the USB driver when many
frequency changes were done.

Stefan

Re: Interl XScale pxa cpufreq driver

[Russell King]

On Mon, Mar 22, 2004 at 04:13:14PM +0100, Stefan Buettcher wrote:
> Young-Jin Kim wrote:
> > Hi, 
> > I know there is no cpufreq driver which supports XScale PXA processor.
> 
> There is one. You could have a look at the kernel sources
> of the ARM Linux project or the Familiar distribution.

It's not part of the ARM kernels, and if its sitting in the
handhelds.org CVS, I don't expect it ever to be.  handhelds.org CVS
is a dumping ground for random stuff and is a failure as far as the
Linux kernel and Open Source goes.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core

Re: Interl XScale pxa cpufreq driver

[Bruno Ducrot]

On Mon, Mar 22, 2004 at 11:10:34PM +0900, Young-Jin Kim wrote:
> And, I want to know if there is a routine of changing the supply voltage in speedstep-ich for Intel Mobile Pentium 4.
> In fact I cannot see well. 

There is no (standardized) way to change default setting of the two core
voltages that can be applyed to a mobile pentium 4.

-- 
Bruno Ducrot

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.

Re: Interl XScale pxa cpufreq driver

[Dominik Brodowski]

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On Mon, Mar 22, 2004 at 11:10:34PM +0900, Young-Jin Kim wrote:
> And, I want to know if there is a routine of changing the supply voltage in speedstep-ich for Intel Mobile Pentium 4.

It's done by the chipset, changing the relevant bit in the southbridge is
enough for speedstep-ich.

	Dominik


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