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