On Thu, 11 Jun 2009, jack craig wrote: > following alan's tip, i have run my program w/no code changes and i dont see any claim errors, weird! > > but i do have a question; consider i am sending via interrupt xfers 2 - 8 byte xfers to my widget > and i read back 2 - 8 byte responses. the dmesg from running my program twice looks like, ... > > > [ 267.640170] usb 3-2: new low speed USB device using uhci_hcd and address 2 > [ 267.808286] usb 3-2: New USB device found, idVendor=1808, idProduct=5555 > [ 267.808302] usb 3-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 > [ 267.808314] usb 3-2: Product: USB to OBD-2 > [ 267.808323] usb 3-2: Manufacturer: Multiplex Engineering > [ 267.808666] usb 3-2: configuration #1 chosen from 1 choice > [ 272.910640] usb 3-2: opened by process 1915: lsusb > [ 272.910881] usb 3-2: opened by process 1915: lsusb > [ 287.653667] usb 3-2: opened by process 1916: obdscan > [ 287.653725] usb 3-2: usbdev_ioctl: GETDRIVER > [ 287.654007] usb 3-2: usbdev_ioctl: IOCTL > [ 287.655850] usb 3-2: usbdev_ioctl: CLAIMINTERFACE > [ 287.657241] usb 3-2: usbdev_ioctl: SUBMITURB > [ 287.657252] usb 3-2: interrupt urb > [ 287.657265] usb 3-2: direction=OUT > [ 287.657271] usb 3-2: userurb=08c74150 > [ 287.657276] usb 3-2: transfer_buffer_length=8 > [ 287.657282] usb 3-2: actual_length=0 > [ 287.657286] usb 3-2: data: e4 80 05 61 6a f1 01 00 > [ 287.664205] usb 3-2: urb complete > [ 287.664214] usb 3-2: direction=OUT > [ 287.664219] usb 3-2: userurb=08c74150 > [ 287.664223] usb 3-2: transfer_buffer_length=8 > [ 287.664227] usb 3-2: actual_length=8 > [ 287.664231] usb 3-2: data: e4 80 05 61 6a f1 01 00 > [ 287.665359] usb 3-2: usbdev_ioctl: REAPURBDELAY ... > [ 300.214387] usb 3-2: opened by process 1920: obdscan > > my question is, seeing the regular pattern of 'actual_length=0', i am guessing that is normal? Yes. The usbfs_snoop code could stand to be improved. It prints out all the data when the URB is first submitted and then again when the URB completes. Of course actual_length is 0 during submission. In addition, there's no reason to dump the data buffer during submissions for an IN transfer or during completion for an OUT transfer. 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
