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usb_buffer_map
Langue: en
Version: October 2010 (fedora - 01/12/10)
Section: 9 (Appels noyau Linux)
NAME
usb_buffer_map - create DMA mapping(s) for an urbSYNOPSIS
- 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 is 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.
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