1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>usb_alloc_urb</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&#160;5.&#160;USB Core APIs"><link rel="prev" href="API-usb-init-urb.html" title="usb_init_urb"><link rel="next" href="API-usb-free-urb.html" title="usb_free_urb"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">usb_alloc_urb</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-usb-init-urb.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;5.&#160;USB Core APIs</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-usb-free-urb.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-usb-alloc-urb"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_alloc_urb &#8212; 
2     creates a new urb for a USB driver to use
3 </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 * <b class="fsfunc">usb_alloc_urb </b>(</code></td><td>int <var class="pdparam">iso_packets</var>, </td></tr><tr><td>&#160;</td><td>gfp_t <var class="pdparam">mem_flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1115939732"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>iso_packets</code></em></span></dt><dd><p>
4     number of iso packets for this urb
5    </p></dd><dt><span class="term"><em class="parameter"><code>mem_flags</code></em></span></dt><dd><p>
6     the type of memory to allocate, see <code class="function">kmalloc</code> for a list of
7     valid options for this.
8    </p></dd></dl></div></div><div class="refsect1"><a name="idp1115942684"></a><h2>Description</h2><p>
9   Creates an urb for the USB driver to use, initializes a few internal
10   structures, increments the usage counter, and returns a pointer to it.
11   </p><p>
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13   If the driver want to use this urb for interrupt, control, or bulk
14   endpoints, pass '0' as the number of iso packets.
15   </p><p>
16
17   The driver must call <code class="function">usb_free_urb</code> when it is finished with the urb.
18</p></div><div class="refsect1"><a name="idp1115944164"></a><h2>Return</h2><p>
19   A pointer to the new urb, or <code class="constant">NULL</code> if no memory is available.
20</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-init-urb.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="usbcore.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-usb-free-urb.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">usb_init_urb</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">usb_free_urb</span></td></tr></table></div></body></html>
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