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<html xmlns="http://www.w3.org/1999/xhtml"><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 V1.75.2" /><link rel="home" href="index.html" title="The Linux-USB Host Side API" /><link rel="up" href="ch04.html" title="Chapter 4. Host-Side Data Types and Macros" /><link rel="prev" href="re39.html" title="usb_urb_dir_out" /><link rel="next" href="ch05.html" title="Chapter 5. USB Core APIs" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>struct usb_sg_request</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re39.html">Prev</a> </td><th width="60%" align="center">Chapter 4. Host-Side Data Types and Macros</th><td width="20%" align="right"> <a accesskey="n" href="ch05.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="struct usb_sg_request"><a id="API-struct-usb-sg-request"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>struct usb_sg_request —
support for scatter/gather I/O
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><pre class="programlisting">
struct usb_sg_request {
int status;
size_t bytes;
}; </pre></div><div class="refsect1" title="Members"><a id="id3107151"></a><h2>Members</h2><div class="variablelist"><dl><dt><span class="term">status</span></dt><dd><p>
zero indicates success, else negative errno
</p></dd><dt><span class="term">bytes</span></dt><dd><p>
counts bytes transferred.
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id3107184"></a><h2>Description</h2><p>
These requests are initialized using <code class="function">usb_sg_init</code>, and then are used
as request handles passed to <code class="function">usb_sg_wait</code> or <code class="function">usb_sg_cancel</code>. Most
members of the request object aren't for driver access.
</p><p>
The status and bytecount values are valid only after <code class="function">usb_sg_wait</code>
returns. If the status is zero, then the bytecount matches the total
from the request.
</p><p>
After an error completion, drivers may need to clear a halt condition
on the endpoint.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re39.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch04.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch05.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>usb_urb_dir_out</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 5. USB Core APIs</td></tr></table></div></body></html>
