Re: Information regarding C3 cpu state and bus mastering activity

Marco Calviani
2005-12-13T20:52:31Z

Hi list,

2005/12/13, phutchis-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org <phutchis-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org>:

> Might be OK, provided the USB host controller *can* be powered down
> *and* we won't need to wake up due to someone touching the USB mouse
> or keyboard :)

Well, in my case the keyboard is not the problem since i'm running a laptop....
Do you know how is possible to power down the usb controller?

I was googling on this problem and i've found a page from Microsoft
support center that describe the same problem (for W2K and ME) on that
OS http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q297045&
They provide this "solution" (as i anticipated some mails ago): "To
resolve this problem, increase the USB polling interval from one ms to
five ms. Then, the processor can enter a C3 power-saving state during
its inactivity and extend the battery life of the computer. To
increase this polling interval, add a registry entry that is dependent
upon the operating system"

Any hint on how to implement this, and do you think that this can
provide some help?

Best regards,
Marco Calviani

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