On Mon, 23 May 2011, Sarah Sharp wrote: > > 2. whether the device HW supports SS protocol. In our scenario it can since > > SS support is enabled in our udc. (We haven't released it yet.) > > What is a UDC? USB Device Controller. It's the device-side analog of a host controller. > > Since in dummy_hcd all of this is much simpler I think that the device speed > > should be determined by driver->speed and "which type of cable the > > connection was made over - SS or HS". The "cable type" is exactly what the > > module parameter is. > > I really don't understand this. You're going to have a module parameter > for what type of cable is plugged in? It would be more accurate to say the module parameter will be used to force the connection to run at a lower speed than the maximum possible. This is kind of like what happens when you plug in a SuperSpeed device using a USB-2 cable -- the connection runs at a lower speed than it could have. > How can you tell which one the > user is going to use? This isn't about actual cables or devices. dummy-hcd is an emulator; it presents as a host controller and a device controller both on the same system. This allows people to test gadget drivers without having any UDC hardware. > What about the case where SuperSpeed enumeration > fails and you have to fall back to high speed? If SuperSpeed enumeration fails, say because the device doesn't have any SuperSpeed descriptors, xhci-hcd doesn't fall back to high speed, does it? dummy-hcd should behave the same way. > It seems like you really > need to handle both speeds and the speed fall back parameter in the same > driver. Isn't there some other gadget driver that has a fall back to > full or low speed when high speed enumeration fails? That's a property of the gadget driver, not the UDC driver. dummy-hcd is a UDC driver (and an HCD too). 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
