On Thu, 1 Sep 2011, Sarah Sharp wrote: > On Thu, Sep 01, 2011 at 11:32:54AM +0300, Felipe Balbi wrote: > > On Wed, Aug 31, 2011 at 10:53:01PM -0400, Alan Stern wrote: > > > Consider xHCI as an example. To what extent does it make sense to > > > suspend/resume the low/full/high-speed bus independently of the > > > SuperSpeed bus? I don't know enough about xHCI to say. > > The xHCI PCI host can only be put in D3 when all ports (USB 3.0 and USB > 2.0) are suspended. So it really makes no sense to suspend the two > buses separately. Even when the PCI controller is at full power, can you save a little extra energy by doing something special at a time when all the enabled LS/FS/HS ports are suspended but some of the SS ports aren't (or vice versa)? With other PCI controllers this sort of power saving is possible. While keeping the controller in D0, you can still turn off the frame counter and the synchronous and async schedules. Does xHCI do this sort of thing automatically? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
