On Mon, 20 Feb 2006, Alan Stern wrote: > On Mon, 20 Feb 2006, Pavel Machek wrote: > > > Hi! > > > > > Can you update the patch to fix this paragraph? > > > > > > > > Well, this is talking about suspend-to-disk... That is expected to > > > > power down machine, without providing USB bus power. If box > > > > suspends-to-disk and leaves USB up, something is wrong with the > > > > machine. > > > > > > Oh, sorry, I didn't realize that. > > > > > > Isn't there an ACPI mode that powers down most things (including RAM) but > > > is able to respond to wakeup events? I can't remember the mode's name, > > > except that it's almost certainly "S" followed by some meaningless number > > > followed by some unhelpful word. :-) Since USB plug/unplug is potentially > > > a wakeup event, such a mode must provide suspend power to the USB > > > controller. > > > > Maybe S4 does that, but I'm not sure... > > > > > Does swsusp still support these not-completely-powered-off modes? > > > > Yes. echo platform > /sys/power/disk. > > So if you did that, you could suspend-to-disk while leaving USB up, right? > Without anything being wrong with the machine. No, not likely. S4 is +/- equivalent to a "soft off", except that it responds to more wake-up events than a soft off will (which BTW is defined as "S5"). Even S3 will power down all of the PCI buses, including the USB host controllers. The chances of having any low-power system state that will still power the USB ports (by design) is pretty slim. Thanks, Pat
