On Tue, 26 May 2015, Rong Wang wrote: > > It seems that your customer wants to change the hardware, not the > > software. > > Yes. We plan to do a hardware modification. But we want to make as little > change as possible. So we plan to make the internal signal HostDisconnect > , which is sent from PHY to indicate a disconnection event, configurable > by software. > We'll mask this signal at first, once the software determines that there's a > disconnection event, we unmask this signal to notify the USB controller. > The advantage of this implementation is that the disconnection indication > signal will not go to USB controller directlly, thus no internal clean up work > will be done, which will make software recovery possible. > The disadvantage is that since there's no disconnection indication signal, > there's no PCD interrupt and no CCS and CSC update avalable. It's totally > determined by software. > We don't konw whether this implementation can handle all the corner cases. Clearly it can't. For example, an unplug would not generate a wakeup event. But maybe you can make it work well enough for your needs. > BTW, how's the USB Device Controller (HS/FS) detetct the disconnection? > Does it detect the disconnection by a SE0 line status or by VBUS status? SE0 line status indicates reset, not disconnect. USB devices detect disconnection by monitoring VBus. 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
