1USB_BUFFER_MAP(9)                USB Core APIs               USB_BUFFER_MAP(9)
2
3
4

NAME

6       usb_buffer_map - create DMA mapping(s) for an urb
7

SYNOPSIS

9       struct urb * usb_buffer_map(struct urb * urb);
10

ARGUMENTS

12       urb
13           urb whose transfer_buffer/setup_packet will be mapped
14

DESCRIPTION

16       URB_NO_TRANSFER_DMA_MAP is added to urb->transfer_flags if the
17       operation succeeds. If the device is connected to this system through a
18       non-DMA controller, this operation always succeeds.
19
20       This call would normally be used for an urb which is reused, perhaps as
21       the target of a large periodic transfer, with usb_buffer_dmasync calls
22       to synchronize memory and dma state.
23
24       Reverse the effect of this call with usb_buffer_unmap.
25

RETURN

27       Either NULL (indicating no buffer could be mapped), or urb.
28

30Kernel Hackers Manual 3.10         June 2019                 USB_BUFFER_MAP(9)
Impressum