1USB_BUFFER_MAP(9)                USB Core APIs               USB_BUFFER_MAP(9)
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NAME

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

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

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

16       Return value is either null (indicating no buffer could be mapped), or
17       the parameter. URB_NO_TRANSFER_DMA_MAP and URB_NO_SETUP_DMA_MAP are
18       added to urb->transfer_flags if the operation succeeds. If the device
19       is connected to this system through a non-DMA controller, this
20       operation always succeeds.
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22       This call would normally be used for an urb which is reused, perhaps as
23       the target of a large periodic transfer, with usb_buffer_dmasync calls
24       to synchronize memory and dma state.
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26       Reverse the effect of this call with usb_buffer_unmap.
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29Kernel Hackers Manual 2.6.         June 2019                 USB_BUFFER_MAP(9)
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