<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>usb_buffer_map</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /><link rel="home" href="index.html" title="The Linux-USB Host Side API" /><link rel="up" href="usbcore.html" title="Chapter 5. USB Core APIs" /><link rel="prev" href="API-usb-free-coherent.html" title="usb_free_coherent" /><link rel="next" href="API-usb-buffer-dmasync.html" title="usb_buffer_dmasync" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">usb_buffer_map</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-usb-free-coherent.html">Prev</a> </td><th width="60%" align="center">Chapter 5. USB Core APIs</th><td width="20%" align="right"> <a accesskey="n" href="API-usb-buffer-dmasync.html">Next</a></td></tr></table><hr /></div><div class="refentry"><a id="API-usb-buffer-map"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_buffer_map — create DMA mapping(s) for an urb </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">struct urb * <strong class="fsfunc">usb_buffer_map </strong>(</code></td><td>struct urb * <var class="pdparam">urb</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="idm140259811404480"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>urb</code></em></span></dt><dd><p> urb whose transfer_buffer/setup_packet will be mapped </p></dd></dl></div></div><div class="refsect1"><a id="idm140259811401280"></a><h2>Description</h2><p> 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. </p><p> This call would normally be used for an urb which is reused, perhaps as the target of a large periodic transfer, with <code class="function">usb_buffer_dmasync</code> calls to synchronize memory and dma state. </p><p> Reverse the effect of this call with <code class="function">usb_buffer_unmap</code>. </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-usb-free-coherent.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="usbcore.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="API-usb-buffer-dmasync.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">usb_free_coherent</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span class="phrase">usb_buffer_dmasync</span></td></tr></table></div></body></html>