1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Chapter&#160;6.&#160;Control Interface</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><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="pcm-interface-constraints.html" title="Constraints"><link rel="next" href="control-interface-definition.html" title="Definition of Controls"></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">Chapter&#160;6.&#160;Control Interface</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="pcm-interface-constraints.html">Prev</a>&#160;</td><th width="60%" align="center">&#160;</th><td width="20%" align="right">&#160;<a accesskey="n" href="control-interface-definition.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="control-interface"></a>Chapter&#160;6.&#160;Control Interface</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="control-interface.html#control-interface-general">General</a></span></dt><dt><span class="section"><a href="control-interface-definition.html">Definition of Controls</a></span></dt><dt><span class="section"><a href="control-interface-control-names.html">Control Names</a></span></dt><dd><dl><dt><span class="section"><a href="control-interface-control-names.html#control-interface-control-names-global">Global capture and playback</a></span></dt><dt><span class="section"><a href="control-interface-control-names.html#control-interface-control-names-tone">Tone-controls</a></span></dt><dt><span class="section"><a href="control-interface-control-names.html#control-interface-control-names-3d">3D controls</a></span></dt><dt><span class="section"><a href="control-interface-control-names.html#control-interface-control-names-mic">Mic boost</a></span></dt></dl></dd><dt><span class="section"><a href="control-interface-access-flags.html">Access Flags</a></span></dt><dt><span class="section"><a href="control-interface-callbacks.html">Callbacks</a></span></dt><dd><dl><dt><span class="section"><a href="control-interface-callbacks.html#control-interface-callbacks-info">info callback</a></span></dt><dt><span class="section"><a href="control-interface-callbacks.html#control-interface-callbacks-get">get callback</a></span></dt><dt><span class="section"><a href="control-interface-callbacks.html#control-interface-callbacks-put">put callback</a></span></dt><dt><span class="section"><a href="control-interface-callbacks.html#control-interface-callbacks-all">Callbacks are not atomic</a></span></dt></dl></dd><dt><span class="section"><a href="control-interface-constructor.html">Constructor</a></span></dt><dt><span class="section"><a href="control-interface-change-notification.html">Change Notification</a></span></dt><dt><span class="section"><a href="control-interface-tlv.html">Metadata</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="control-interface-general"></a>General</h2></div></div></div><p>
2        The control interface is used widely for many switches,
3      sliders, etc. which are accessed from user-space. Its most
4      important use is the mixer interface. In other words, since ALSA
5      0.9.x, all the mixer stuff is implemented on the control kernel API.
6      </p><p>
7        ALSA has a well-defined AC97 control module. If your chip
8      supports only the AC97 and nothing else, you can skip this
9      section. 
10      </p><p>
11        The control API is defined in
12      <code class="filename">&lt;sound/control.h&gt;</code>.
13      Include this file if you want to add your own controls.
14      </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pcm-interface-constraints.html">Prev</a>&#160;</td><td width="20%" align="center">&#160;</td><td width="40%" align="right">&#160;<a accesskey="n" href="control-interface-definition.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Constraints&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;Definition of Controls</td></tr></table></div></body></html>
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