Provided by: linux-doc-2.6.15_2.6.15-23.39_all bug


       usb_buffer_map - create DMA mapping(s) for an urb


       struct urb * usb_buffer_map  (struct urb * urb);


       urb    urb whose transfer_buffer/setup_packet will be mapped


       Return  value is either null (indicating no buffer could be mapped), or
       the parameter.  URB_NO_TRANSFER_DMA_MAP  and  URB_NO_SETUP_DMA_MAP  are
       added  to  urb->transfer_flags if the operation succeeds. If the device
       is  connected  to  this  system  through  a  non-DMA  controller,  this
       operation always succeeds.

       This call would normally be used for an urb which is reused, perhaps as
       the target of a large periodic transfer, with usb_buffer_dmasync  calls
       to synchronize memory and dma state.

       Reverse the effect of this call with usb_buffer_unmap.