Messages in this thread | | | Date | Mon, 24 Mar 2003 16:28:01 -0800 | From | Greg KH <> | Subject | Re: usb printer driver and zero length transfer |
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On Mon, Mar 24, 2003 at 11:51:50AM -0800, Kallol Biswas wrote: > Hi, > I am new to USB world and looking for clarification on usb > printer's > behavior when transferring data with size multiple of wMaxPacketSize. > > I have been running redhat 7.1 (linux kernel 2.4.2-2) on x86 PC with a > USB 1.1 controller. There is a target mode printer driver running on the > > other side. > > On the host the device file is /dev/usb/lp0. > If a data packet of 64 bytes is sent with > > "cat data8 > /dev/usb/lp0" , the size of data8 is 64, a zero length > packet > at the end of the transfer is not sent. > > Is this a correct behavior? How do we force the printer driver send > a zero length packet at the end of a transfer if the packet size is > a multiple of wMAxPacketSize?
If your device requires that a zero length packet be send for this situation, then modify the transfer flags of the urb with URB_ZERO_PACKET to cause this to happen.
Hope this helps,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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