Re: Pentium III (Coppermine) cpufreq support

[Ducrot Bruno <ducrot@poupinou.org>]

On Thu, Jan 29, 2004 at 02:18:19PM +0100, aeriksson2@fastmail.fm wrote:
> 
> Ducrot Bruno <ducrot@poupinou.org> said:
> > > > And?  This code is shared with *all* speedstep drivers.
> > > > 
> > > 
> > > I know the detection code is shared. I assumed that the failure modes
> > > might be different for the different divers. I.e. a mis-detected cpu
> > > using the ich driver might cause a hang, while a mis-detected cpu on
> > > the -smi driver might cause a small fire, be undetected, whatever.
> > > Maybe that's a wromng assumption.
> > 
> > The fact that a mis-detected cpu in the ich case introduce a freeze
> > of a system is enough to not include your patch in this form, no matter
> > if it is safe (and I believe that it is the case) in the smi case.
> > 
> OK. Right. I agree. Another solution is needed, then.
> 
> <snip>
> > Systems that support SMI call, but do not pass the speedstep capabilty
> > check.  There is even one that do not support the int15 check, that
> > do not pass the speedstep capabitility check, but speedstep-smi driver
> > work.
> > 
> > Therefore, there is no need to get feedback for this particular point,
> > because it is already well known (at least by me) and I must admit
> > that I should have fixed, and documented, this problem (my fault,
> > my big fault, sorry)...
> 
> Fixed as in fixing code somewhere, or "just" document that it doesn't
> work (and perhaps never will)? If you have a plan for code mods to get
> this to work, please announce it and I/we can start hacking on it. I
> don't like having to patch the source for each upgrade...
> 
> Do we need more data points? I know my patch removes two bits from the
> test pattern. I have not checked if that's needed, or which bit is the
> offender. Should I check that, or is the culprit elsewhere?

Dominik have done some research in order to be sure that early coppermines
are speedstep capable.  I think he got the most possible bit in the check
routines.  So I'm afraid the only solution is to make a fix to release
somehow the offending check via a kernel option (this may be
usefull for speedstep-piix4 for example).

Documentation occur when adding stuff in
Documentation/kernel-parameters.txt if you choose the kernel boot
option and optionaly to add an howto in Documentation/cpu-freq/
for more detailed explanations.

-- 
Ducrot Bruno

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