Please format your email text to wrap after 72 columns or so. On Fri, 20 Nov 2009, Günter Gebhardt wrote: > Hello, > > I use the usb_bulk_msg() kernel function to write and read to and > from a USB device respectively. > Sometimes the usb_bulk_msg() is missing to deliver an incoming > packet. How do you know? > This packet is seen however by an USB analyser (Beagle USB 480). A > fragment of the Beagle log is located in the attachment beagle.csv. > The packets in concern have the index number 1132287 and 1132325, > where the first is a device request and the latter is the missing > corresponding response. How do you know it is missing? > A measurement with usbmon shows that this very response is not > delivered by the host controller driver. The packet with index > d3196a40 in the attachments usbmon.txt (complete traffic) and > usbmon_filtered.txt (only the traffic with the device in concern) > show that the request is sent to device but the corresponding > response is never delivered. usbmon sometimes drops events. The response may very well have been received by usb_bulk_msg() even though it did not show up in the usbmon trace. The only way to tell for certain that it wasn't received is to have your driver print a log message before and after it calls usb_bulk_msg(). 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
