On Friday, 13 October 2006 10:39, Thomas Renninger wrote: > 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... Alan Stern has been working on USB autosuspend for quite some time and there are some patches in -mm and in the recent mainline, AFAICT. Greetings, Rafael -- You never change things by fighting the existing reality. R. Buckminster Fuller - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
