On Tue, Jul 17, 2012 at 10:49:26PM +0800, Lan Tianyu wrote: > On 2012/7/17 22:26, Alan Stern wrote: > >On Tue, 17 Jul 2012, Oliver Neukum wrote: > > > >>>Yeah. Lost some background introduction. I recently try to realize usb > >>>port power off mechanism for ports with device. So design, the port with > >>>device only can be power off when remote wakeup disable. > > > >Why is that? What happens if you power-off a port where the device has > >remove wakeup enabled? > > > I will not power off a port where the device has remote wakeup enabled. > Only when disabled, the port will power off. The reason behind this is because we will lose remote wakeups when the port is powered off. The port power is completely removed and it looks like a physical disconnect to both the host and the device. So we can't power off a port where the device has remote wakeup enabled. Sarah Sharp -- 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
