Re: patch: p4tcc and speedstep cpufreq drivers
From: Maxim Sobolev (sobomax_at_portaone.com)
Date: 02/25/05
- Previous message: Martin Nilsson: "5.4 and USB keyboard support"
- In reply to: Chuck Swiger: "Re: patch: p4tcc and speedstep cpufreq drivers"
- Next in thread: Freddie Cash: "Re: patch: p4tcc and speedstep cpufreq drivers"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Date: Fri, 25 Feb 2005 10:55:56 +0200 To: Chuck Swiger <cswiger@mac.com>
Chuck Swiger wrote:
> Maxim Sobolev wrote:
>
>> Nate Lawson wrote:
>
> [ ... ]
>
>>> "On-Demand mode may be used at the same time Automatic mode is
>>> enabled, however, if the system (tries to enable the TCC via
>>> On-Demand mode[1]) at the same time (automatic mode is enabled[2])
>>> AND (a high temperature condition exists [3]), the duty cycle of the
>>> automatic mode will override the duty cycle selected by the On-Demand
>>> mode."
>>>
>>> Since automatic mode is set by the BIOS before we even boot, things
>>> should be fine.
>>
>>
>> Well, this is quite tricky part of the spec. My reading is that the
>> paragraph above applies only to situation if you are (trying to set
>> on-demand mode [1]) when both (automatic mode is in effect [2]) *and*
>> (high temperature condition already exists [3]), in that case
>> automatic mode will win and override any manual settings.
>
>
> I suspect you'd read your paragraph with [1] and [2] joined together,
> but they can be read seperately just as the spec can. :-)
>
>> However, in the case when you have on-demand mode already on and high
>> temperature condition emerges it will have no effect on duty cycle
>> until THERMTRIP# kicks in.
>>
>> That's in my view explains why there is big AND in the text above.
>
>
> I think the spec is advising developers who try to control TCC that if
> PROCHOT gets asserted, the CPU may override the programmed settings in
> favor of the automatic ones. I don't think the spec is asserting that
> the CPU is forbidden from reducing power usage if PROCHOT condition is
> detected, regardless of what automatic mode is set to.
>
> A reasonable processor would drop to a known minimal power usage state--
> hopefully one low enough to keep the CPU from completely overheating
> even if a fan has failed-- if PROCHOT is seen.
>
> [ It may also be the case that a CPU does not do so, in which case the
> ACPI driver code ought to try to pay attention to PROCHOT and reduce
> power consumption regardless and not just depend on CPU failsafes to
> work. If that is your position, well, I would agree with this. :-) ]
Check the original spec, there is a note at the end of the respective
paragraph (particularly the first sentence):
If automatic mode is disabled the processor will be operating out of
specification and
cannot be guaranteed to provide reliable results. Regardless of enabling
of the automatic
or On-Demand modes, in the event of a catastrophic cooling failure, the
processor will
automatically shut down when the silicon has reached a temperature of
approximately
135 °C. At this point the system bus signal THERMTRIP# will go active
and stay active
until RESET# has been initiated. THERMTRIP# activation is independent of
processor
activity and does not generate any bus cycles. If THERMTRIP# is
asserted, processor
core voltage (Vcc) must be removed within the timeframe defined in Table 16.
-Maxim
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org"
- Previous message: Martin Nilsson: "5.4 and USB keyboard support"
- In reply to: Chuck Swiger: "Re: patch: p4tcc and speedstep cpufreq drivers"
- Next in thread: Freddie Cash: "Re: patch: p4tcc and speedstep cpufreq drivers"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
Relevant Pages
|
