On Tue, 10 Nov 2009, Daniel Glöckner wrote: > On Tue, Nov 10, 2009 at 01:45:44PM -0500, Alan Stern wrote: > > I don't understand the code, but your description is wrong. The > > response to a control-IN request should _not_ be followed by a ZLP even > > if the amount transferred is an exact multiple of the maxpacket size > > and the "zero" flag is set, provided the length is equal to the wLength > > value in the setup packet. > > > > ZLP's are used only to delimit _short_ transfers. If the length is the > > same as what the host asked for, then it isn't short. > > Drivers set the zero flag only on short transfers, usually like this: > > request->zero = (length < wLength); > > See for example composite.c:composite_setup() right before usb_ep_queue > or file_storage.c:fsg_setup() right before ep0_queue. I apologize; you are right. Drivers will never set the zero flag if the transfer is full-length. 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
