<?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>Registration and Release</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Writing an ALSA Driver" /><link rel="up" href="ch03.html" title="Chapter 3. Management of Cards and Components" /><link rel="prev" href="ch03s03.html" title="Chip-Specific Data" /><link rel="next" href="ch04.html" title="Chapter 4. PCI Resource Management" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Registration and Release</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch03s03.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Management of Cards and Components</th><td width="20%" align="right"> <a accesskey="n" href="ch04.html">Next</a></td></tr></table><hr /></div><div class="section" title="Registration and Release"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="card-management-registration"></a>Registration and Release</h2></div></div></div><p> After all components are assigned, register the card instance by calling <code class="function">snd_card_register()</code>. Access to the device files is enabled at this point. That is, before <code class="function">snd_card_register()</code> is called, the components are safely inaccessible from external side. If this call fails, exit the probe function after releasing the card via <code class="function">snd_card_free()</code>. </p><p> For releasing the card instance, you can call simply <code class="function">snd_card_free()</code>. As mentioned earlier, all components are released automatically by this call. </p><p> As further notes, the destructors (both <code class="function">snd_mychip_dev_free</code> and <code class="function">snd_mychip_free</code>) cannot be defined with the <em class="parameter"><code>__devexit</code></em> prefix, because they may be called from the constructor, too, at the false path. </p><p> For a device which allows hotplugging, you can use <code class="function">snd_card_free_when_closed</code>. This one will postpone the destruction until all devices are closed. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch03s03.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="ch04.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chip-Specific Data </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 4. PCI Resource Management</td></tr></table></div></body></html>