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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>Chapter 6. Control Interface</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="index.html" title="Writing an ALSA Driver" /><link rel="prev" href="ch05s09.html" title="Constraints" /><link rel="next" href="ch06s02.html" title="Definition of Controls" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 6. Control Interface</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch05s09.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ch06s02.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter 6. Control Interface"><div class="titlepage"><div><div><h2 class="title"><a id="control-interface"></a>Chapter 6. Control Interface</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="ch06.html#control-interface-general">General</a></span></dt><dt><span class="section"><a href="ch06s02.html">Definition of Controls</a></span></dt><dt><span class="section"><a href="ch06s03.html">Control Names</a></span></dt><dd><dl><dt><span class="section"><a href="ch06s03.html#control-interface-control-names-global">Global capture and playback</a></span></dt><dt><span class="section"><a href="ch06s03.html#control-interface-control-names-tone">Tone-controls</a></span></dt><dt><span class="section"><a href="ch06s03.html#control-interface-control-names-3d">3D controls</a></span></dt><dt><span class="section"><a href="ch06s03.html#control-interface-control-names-mic">Mic boost</a></span></dt></dl></dd><dt><span class="section"><a href="ch06s04.html">Access Flags</a></span></dt><dt><span class="section"><a href="ch06s05.html">Callbacks</a></span></dt><dd><dl><dt><span class="section"><a href="ch06s05.html#control-interface-callbacks-info">info callback</a></span></dt><dt><span class="section"><a href="ch06s05.html#control-interface-callbacks-get">get callback</a></span></dt><dt><span class="section"><a href="ch06s05.html#control-interface-callbacks-put">put callback</a></span></dt><dt><span class="section"><a href="ch06s05.html#control-interface-callbacks-all">Callbacks are not atomic</a></span></dt></dl></dd><dt><span class="section"><a href="ch06s06.html">Constructor</a></span></dt><dt><span class="section"><a href="ch06s07.html">Change Notification</a></span></dt><dt><span class="section"><a href="ch06s08.html">Metadata</a></span></dt></dl></div><div class="section" title="General"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="control-interface-general"></a>General</h2></div></div></div><p>
The control interface is used widely for many switches,
sliders, etc. which are accessed from user-space. Its most
important use is the mixer interface. In other words, since ALSA
0.9.x, all the mixer stuff is implemented on the control kernel API.
</p><p>
ALSA has a well-defined AC97 control module. If your chip
supports only the AC97 and nothing else, you can skip this
section.
</p><p>
The control API is defined in
<code class="filename"><sound/control.h></code>.
Include this file if you want to add your own controls.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch05s09.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="ch06s02.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Constraints </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Definition of Controls</td></tr></table></div></body></html>
