On Fri, 27 Jan 2012, Klaus Rudolph wrote: > Hi Alan, > > This means that the host thinks it sent an 8-byte SETUP packet followed > > by a 24-byte data-OUT packet. > > > >> And as I told you, I have no idea where to put that packet? > > > > Most likely, the SETUP packet _was_ sent and either your hardware or > > your driver lost it. > > > > My hardware has different buffers for each endpoint. As I understand > you, the host try to send a setup packet 8 bytes AND a 24 bytes packet > to another (bulk) endpoint. No, no. The host sent an 8-byte SETUP packet to ep0 followed by a 24-byte data-OUT packet to ep0. > But why wireshark could not see the two > packets? Wireshark for USB doesn't see packets at all. It sees only URBs, which are purely software entities. Each URB corresponds to multiple packets. The URB you posted was a 24-byte control-OUT transfer, which means the hardware will try to carry out three transactions: SETUP (8 bytes), data-OUT (24 bytes), and data-IN (0 bytes). And if you want to be really technical about it, each transaction consists of multiple packets: The SETUP transaction involves the host sending a SETUP packet and the device replying with an ACK packet. The data-OUT transaction involves the host sending an OUT packet and a DATA0 packet, followed by the device replying with an ACK packet. (Or the device might reply with NAK, in which case host will retry the OUT and DATA0 packets.) The data-IN transaction involves the host sending an IN packet, the device replying with a 0-length DATA1 packet, and then the host sending an ACK packet. > I could believe that my hardware do mysterious things and my > driver also, but how could the tracer show the things in that way? > > I maybe have Monday the chance to look directly on the bus with a > hardware tracer. Maybe this clears the fog a bit :-) That's a good thing to try. 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
