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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>parport_yield</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Device Drivers" /><link rel="up" href="ch03.html" title="Chapter 3. Parallel Port Devices" /><link rel="prev" href="ch03.html" title="Chapter 3. Parallel Port Devices" /><link rel="next" href="re279.html" title="parport_yield_blocking" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>parport_yield</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch03.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Parallel Port Devices</th><td width="20%" align="right"> <a accesskey="n" href="re279.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="parport_yield"><a id="API-parport-yield"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>parport_yield —
relinquish a parallel port temporarily
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">parport_yield </b>(</code></td><td>struct pardevice * <var class="pdparam">dev</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id3064864"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>dev</code></em></span></dt><dd><p>
a device on the parallel port
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id3064891"></a><h2>Description</h2><p>
This function relinquishes the port if it would be helpful to other
drivers to do so. Afterwards it tries to reclaim the port using
<code class="function">parport_claim</code>, and the return value is the same as for
<code class="function">parport_claim</code>. If it fails, the port is left unclaimed and it is
the driver's responsibility to reclaim the port.
</p><p>
The <code class="function">parport_yield</code> and <code class="function">parport_yield_blocking</code> functions are for
marking points in the driver at which other drivers may claim the
port and use their devices. Yielding the port is similar to
releasing it and reclaiming it, but is more efficient because no
action is taken if there are no other devices needing the port. In
fact, nothing is done even if there are other devices waiting but
the current device is still within its <span class="quote">“<span class="quote">timeslice</span>”</span>. The default
timeslice is half a second, but it can be adjusted via the /proc
interface.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch03.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re279.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 3. Parallel Port Devices </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>parport_yield_blocking</span></td></tr></table></div></body></html>
