1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>struct usb_sg_request</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="hostside.html" title="Chapter&#160;4.&#160;Host-Side Data Types and Macros"><link rel="prev" href="API-usb-urb-dir-out.html" title="usb_urb_dir_out"><link rel="next" href="usbcore.html" title="Chapter&#160;5.&#160;USB Core APIs"></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">struct usb_sg_request</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-usb-urb-dir-out.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;4.&#160;Host-Side Data Types and Macros</th><td width="20%" align="right">&#160;<a accesskey="n" href="usbcore.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-struct-usb-sg-request"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>struct usb_sg_request &#8212; 
2     support for scatter/gather I/O
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="programlisting">
4struct usb_sg_request {
5  int status;
6  size_t bytes;
7};  </pre></div><div class="refsect1"><a name="idp1115920756"></a><h2>Members</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term">status</span></dt><dd><p>
8   zero indicates success, else negative errno
9      </p></dd><dt><span class="term">bytes</span></dt><dd><p>
10   counts bytes transferred.
11      </p></dd></dl></div></div><div class="refsect1"><a name="idp1115922724"></a><h2>Description</h2><p>
12   These requests are initialized using <code class="function">usb_sg_init</code>, and then are used
13   as request handles passed to <code class="function">usb_sg_wait</code> or <code class="function">usb_sg_cancel</code>.  Most
14   members of the request object aren't for driver access.
15   </p><p>
16
17   The status and bytecount values are valid only after <code class="function">usb_sg_wait</code>
18   returns.  If the status is zero, then the bytecount matches the total
19   from the request.
20   </p><p>
21
22   After an error completion, drivers may need to clear a halt condition
23   on the endpoint.
24</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-urb-dir-out.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="hostside.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="usbcore.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">usb_urb_dir_out</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;Chapter&#160;5.&#160;USB Core APIs</td></tr></table></div></body></html>
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