USB_BUFFER_MAP(9) USB Core APIs USB_BUFFER_MAP(9)
NAME
usb_buffer_map - create DMA mapping(s) for an urb
SYNOPSIS
struct urb * usb_buffer_map(struct urb * urb);
ARGUMENTS
urb
urb whose transfer_buffer/setup_packet will be mapped
DESCRIPTION
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.
COPYRIGHT
Kernel Hackers Manual 2.6. July 2010 USB_BUFFER_MAP(9)
