On Wed, 22 Jun 2011, Felipe Balbi wrote: > Hi, > > On Wed, Jun 22, 2011 at 04:20:16PM +0400, Dmitry Eremin-Solenikov wrote: > > Some platforms would like to disable D+ pullup on suspend, to drain as > > low power, as possible. E.g. this was requested by mioa701 board > > maintainers. > > I think this makes sense to many platforms, but by doing so, you would > loose connection to the Host PC, so you need to make sure your device > isn't been used before you go down this road. In fact, something like this is _necessary_ for all UDC/PHY drivers unless the device can guarantee that it will automatically wake up from suspend in time to service a USB packet (note that the window for responding to a packet is only a few microseconds). Otherwise the device would appear to the host to be unresponsive and broken -- better to do a clean disconnect. If suspending the device while it is in use would cause problems ... then don't suspend it when it is in use! 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
