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. Daniel -- Dipl.-Math. Daniel Glöckner, emlix GmbH, http://www.emlix.com Fon +49 551 30664-0, Fax -11, Bahnhofsallee 1b, 37081 Göttingen, Germany Sitz der Gesellschaft: Göttingen, Amtsgericht Göttingen HR B 3160 Geschäftsführung: Dr. Uwe Kracke, Ust-IdNr.: DE 205 198 055 emlix - your embedded linux partner -- 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
