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.TH "USB_BUFFER_MAP" "9" "09 October 2005" "" ""

.SH NAME
usb_buffer_map \- create DMA mapping(s) for an urb
.SH SYNOPSIS
"SYNOPSIS"
.sp
\fB
.sp
struct urb * usb_buffer_map  (struct urb * \fIurb\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIurb\fB\fR
urb whose transfer_buffer/setup_packet will be mapped
.SH "DESCRIPTION"
.PP
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.
.PP
This call would normally be used for an urb which is reused, perhaps
as the target of a large periodic transfer, with \fBusb_buffer_dmasync\fR
calls to synchronize memory and dma state.
.PP
Reverse the effect of this call with \fBusb_buffer_unmap\fR\&.