On Monday, 20 August 2007 22:19, Pavel Machek wrote: > Hi! > > > > > > If I rmmod "ehci-hcd" then the power consumption is back to 69 W. This > > > > > confirms that this is really USB-related. I have to admit that I did > > > > > not expect an external drive to eat that much power from the system, > > > > > especially when not used. I am told that VIA chips are notoriously bad > > > > > at this kind of things. I'll try the same external drive on an Intel > > > > > system later today. > > > > > > > > > > The last mystery remaining is how USB "activity" can cause my CPU to > > > > > heat. I would expect the south bridge to heat, not the CPU. > > > > > > > > USB, or strictly speaking EHCI, OHCI and UHCI, use DMA. To allow > > > > that the cache coherency logic has to be active. Therefore your CPU > > > > cannot go to C3. Therefore it draws more power. The problem we are > > > > facing in USB is that to get great savings, our coverage has to be > > > > perfect. > > > > One device that cannot be autosuspended and we lose most savings. > > > > > > Ok.. but CONFIG_USB_SUSPEND should not really have anything to do with > > > CONFIG_SUSPEND (= s2ram). Perhaps it should depend on CONFIG_PM > > > instead? > > > > CONFIG_USB_SUSPEND doesn't depend on CONFIG_SUSPEND. > > Strange... what is going on here, then? > > config USB_SUSPEND > bool "USB selective suspend/resume and wakeup (EXPERIMENTAL)" > depends on USB && PM && EXPERIMENTAL > help > If you say Y here, you can use driver calls or the sysfs > "power/state" file to suspend or resume individual USB > peripherals. > > Also, USB "remote wakeup" signaling is supported, whereby > some > USB devices (like keyboards and network adapters) can wake > up > their parent hub. That wakeup cascades up the USB tree, and > could wake the system from states like suspend-to-RAM. > > If you are unsure about this, say N here. > > config USB_OTG > bool > depends on USB && EXPERIMENTAL > select USB_SUSPEND > default n > > hmmm, it looks like USB_OTG can be selected without CONFIG_PM, but it > selects USB_SUSPEND. Is that okay?
Well, I don't think so. It should depend on the same things as USB_SUSPEND, IMO. Greetings, Rafael - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
