Laptop ACPI question

[Peter Schuller]

> SpeedStep, as I understand it, is adjustment of the CPU clock speed and
> is VERY directly tied to battery life. It is what systems supporting
> SpeedStep adjust when moving from AC to battery modes. E.g. my T30, by
> default, runs at 1.8 GHz on AC and 1.2 GHz on battery (with my BIOS
> configuration). SpeedStep is a marketing name and I am unwilling to say
> that it is limited to the CPU speed. It may include some of the other
> power management tools like deep sleep modes.

Ah, okay. In that case it seems to be party supported already (on 5.2, I think 
even 5.1). Or if not SpeedStep, then some alternative to it. On the T40p I am 
able to control the speed of the CPU in performance/economy mode by modifying 
sysctl variables.

(Though I am actually running with APM since ACPI causes hangs - though I'm 
just about to try it on CURRENT.)

> Support of CPU frequency is something that is actively being developed
> and will almost certainly be in 5.3. PCI power mode support is also in
> active development and was committed to CURRENT a few weeks ago, but at
> least partly backed out due to problems on a few laptops. (It worked
> GREAT on mine, though). I hope it is returned soon as it make my sound
> work after a suspend.

I remember reading about the PCI stuff and the DPMS/screen poweroff issue on 
-current. But I must have missed the part about it involving power saving, I 
thought it was just bug/crash fixes.

> So power management is getting closer all the time and I am pretty
> confident (for someone who is NOT writing the code) that it will all be
> ready when V5 is declared STABLE.

Looking forward to a 5-STABLE regardless :)

Thanks!

-- 
/ Peter Schuller, InfiDyne Technologies HB

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