On Fri, 25 Aug 2006, Pavel Machek wrote: > Hi! > > > > The frequency of entering this state should not interfere with my active > > > use case. > > > > > > -B- After I've put down the USB device, I now can program the internal > > > SOC bus wrapper for the USB to allow idling of the interconnect. I also > > > need to associate the USB remote wake interrupt with a wake up interrupt > > > to restart my interconnect. All devices on that interconnect must be in > > > the same state for the big savings to happen. > > > > > > Certainly for this embedded system, not coordinating the device states > > > means I can't get the big power savings. > > > > Part of this programming has to be done in the architecture-specific > > driver for the interconnect. There already is code being developed to > > suspend USB buses when they aren't in use (although determining _when_ > > they aren't in use has not yet been implemented). However this code > > stops > > Are there some patches to test? I'd like to power down USB bus, even > when it has device connected (I do not user fingerprint scanner that > much). There are some old patches. I could update them to the current -mm kernel and post them next week. The idea of the patches is that they will autosuspend a USB hub when it has no active (i.e., unsuspended) children, and autosuspending a root hub stops the USB controller from doing DMA. However, non-hub devices are not yet automatically suspended, so you will have to suspend the fingerprint scanner by hand. Alan Stern
