linux-kernel - Re: [PATCH 2/2] CPUFREQ: Mark e_powersaver driver as EXPERIMENTAL and DANGEROUS

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Message-Id: <200906080815.52468.lkml@morethan.org>
Date:	Mon, 8 Jun 2009 08:15:50 -0500
From:	"Michael S. Zick" <lkml@...ethan.org>
To:	Harald Welte <HaraldWelte@...tech.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Duane Griffin <duaneg@...da.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...hat.com>
Subject: Re: [PATCH 2/2] CPUFREQ: Mark e_powersaver driver as EXPERIMENTAL and DANGEROUS

On Mon June 8 2009, Michael S. Zick wrote:
> On Mon June 8 2009, Harald Welte wrote:
> > The e_powersaver driver for VIA's C7 CPU's needs to be marked as
> > DANGEROUS as it configures the CPU to power states that are out
> > of specification.
> > 
> 
> I'll put this and your acpi proposal into a test build today - -
> If my machine survives, I'll post the build for others to try.
> 
> The current build posted (-09159) does not have *either* control
>
Sorry - typo - today is of course the 159th day of the year - -
The previously posted build *without* either control is the -09156.  ;)

Mike
> included, leaving the machine running at silicon "#reset" conditions.
> Slow - but safe.
> 
> Mike
> > According to Centaur, all systems with C7 and Nano CPU's support
> > the ACPI p-state method.  Thus, the acpi-cpufreq driver should
> > be used instead.
> > 
> > Signed-off-by: Harald Welte <HaraldWelte@...tech.com>
> > ---
> >  arch/x86/kernel/cpu/cpufreq/Kconfig |    9 ++++++---
> >  1 files changed, 6 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/cpufreq/Kconfig b/arch/x86/kernel/cpu/cpufreq/Kconfig
> > index 52c8398..f138c6c 100644
> > --- a/arch/x86/kernel/cpu/cpufreq/Kconfig
> > +++ b/arch/x86/kernel/cpu/cpufreq/Kconfig
> > @@ -220,11 +220,14 @@ config X86_LONGHAUL
> >  	  If in doubt, say N.
> >  
> >  config X86_E_POWERSAVER
> > -	tristate "VIA C7 Enhanced PowerSaver"
> > +	tristate "VIA C7 Enhanced PowerSaver (DANGEROUS)"
> >  	select CPU_FREQ_TABLE
> > -	depends on X86_32
> > +	depends on X86_32 && EXPERIMENTAL
> >  	help
> > -	  This adds the CPUFreq driver for VIA C7 processors.
> > +	  This adds the CPUFreq driver for VIA C7 processors.  However, this driver
> > +	  does not have any safeguards to prevent operating the CPU out of spec
> > +	  and is thus considered dangerous.  Please use the regular ACPI cpufreq
> > +	  driver, enabled by CONFIG_X86_ACPI_CPUFREQ.
> >  
> >  	  If in doubt, say N.
> >  
> 
> 
> --
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