On Wed, 14 Jul 2004, John Que wrote: > Hello, > > I am working with usb pwc webcam driver. > > I am trying to set alternate setting different than the > default one. > > To achieve it,I had tried to call usb_set_interface() > with altenate setting 1 (different than default.) > > The usb_set_interface() call succeeds (I can verify it by > making another call to usb_set_interface() as was suggested bt > Alan Stern in this forum ; > see : > http://marc.theaimsgroup.com/?l=linux-usb-devel&m=108860856823230&w=2). > > > > the result is : > I do reach the pwc_isoc_handler (this is the completion > callback). > > The problem is that it reaches pwc_isoc_handler in an endless loop , > instead of exiting after some iterations, as in the normal situation. > > When getting iso packets, the data is in urb->iso_frame_desc array. > > The actual_length field of iso_frame_desc denotes the length of the packet. > > By debugging I saw that it reaches the handler with > actual_length=0 ; the status, however, is 0 (success). > > urb->number_of_packets is 10. > > After 31 interations, the actual_length is 3 , but the status is -75 ; > (this status means EOVERFLOW ; Value too large for defined data type ) > > > (in the default case , the actual length is 291, 1 less than tha MxPS of > the default > alternate setting , which is 292). > > Any idea what the problem can be ?
Can you provide more information? It would help to know, for each entry in the iso_frame_desc array, the values of length, actual_length, and status. In your message it's not clear when you mention "actual_length" whether you mean "urb->actual_length" or urb->iso_frame_desc[n].actual_length". Likewise, does "status" refer to "urb->status" or "urb->iso_frame_desc[n].status"? Try to be more precise in your writing. Also, what do you mean by "After 31 iterations"? Does each iteration examine a different entry in the iso_frame_desc array? If so, and that array has only 10 entries, this doesn't make any sense. If not, then what is being iterated? Alan Stern ------------------------------------------------------- This SF.Net email sponsored by Black Hat Briefings & Training. Attend Black Hat Briefings & Training, Las Vegas July 24-29 - digital self defense, top technical experts, no vendor pitches, unmatched networking opportunities. Visit www.blackhat.com _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
