Re: Centrino question

Karol Kozimor
2004-05-25T23:56:10Z

Thus wrote Alexander Hoogerhuis:
> I've been through tracking down what disables C3 on my laptop (HP
> nc6000). It all happens when the uhci-hci USB drviver goes in. When I
> queried about it on lkml a while back it was due tro some support
> lacking in the UHCI dirvers as of yet.

Whenever something is plugged into the controller, bus mastering kicks in
and C3 is effectively disabled, also on Windows. This is, to my best
knowledge, a limitation of the USB interface itself. As far as I know, at
least uhci-hcd driver in 2.6 suspends the controller when nothing is
plugged in, thus allowing to use C3. The situation might be different under
2.4.
Best regards,

--
Karol 'sziwan' Kozimor
sziwan-DETuoxkZsSqrDJvtcaxF/A@public.gmane.org