On Thu, 2006-10-12 at 22:54 -0700, Kaburlasos, Nikos wrote: > Does anyone know whether the linux USB drivers support the suspend > feature on idle USB ports (i.e. the port has been idle for sometime and > so the driver transitions it in to a low-power 'suspend' state) while > the system is active and in S0 state? As far as I know, Windows don't > support that, I was wondering if linux does. > > Please note, I have no background on linux or in OS programming (I am a > hardware guy), so please be gentle with the level of technical detail in > your response :-)
AFAIK linux is not doing that. Therefore the ohci (also uhci?) drivers need to poll the ports quite often even there is no device attached. This makes C-states less efficient (what should save more power than the suspended USB ports). I thought Windows is doing that, I at least heard Mac OS is doing it like that, but I don't know for sure. The proper solution to avoid polling should be to suspend idle ports, stop polling and wait for some kind of resume/attach event, but AFAIK nobody really works on that. Would be nice if someone gives this a try... Thomas - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
