'\" t
.\"     Title: usb_buffer_map
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: USB Core APIs
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "USB_BUFFER_MAP" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "USB Core APIs"
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.SH "NAME"
usb_buffer_map \- create DMA mapping(s) for an urb
.SH "SYNOPSIS"
.HP \w'struct\ urb\ *\ usb_buffer_map('u
.BI "struct urb * usb_buffer_map(struct\ urb\ *\ " "urb" ");"
.SH "ARGUMENTS"
.PP
\fIurb\fR
.RS 4
urb whose transfer_buffer/setup_packet will be mapped
.RE
.SH "DESCRIPTION"
.PP
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\&.
.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\&.
.SH "RETURN"
.PP
Either
\fBNULL\fR
(indicating no buffer could be mapped), or
\fIurb\fR\&.
.SH "COPYRIGHT"
.br