On Sat, 4 Dec 2004, Pavel Machek wrote: > > For systems that don't provide VBUS current during the > > upcoming system sleep state, it'd be more appropriate > > to just disconnect() the drivers. > > No. Devices can have external power supplies. This is a tricky matter. With no VBUS current, it will appear to the host that the device has been disconnected. When the system awakens, it will see a disconnect followed by a new connection on the same port. This will have the effect of unbinding and then rebinding the driver anyway, regardless of whether the device had its own external power supply. (Note that the USB standard does not allow devices to power their bus segment; only the upstream port is allowed to provide power.) Since the final result is the same, it doesn't matter too much whether the driver gets unbound before the sleep transition or after the wakeup. Alan Stern
