1<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>vb2_fileio_is_active</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Linux Device Drivers"><link rel="up" href="mediadev.html#id-1.8.2" title="Video2Linux devices"><link rel="prev" href="API-vb2-is-streaming.html" title="vb2_is_streaming"><link rel="next" href="API-vb2-is-busy.html" title="vb2_is_busy"></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"><span class="phrase">vb2_fileio_is_active</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-vb2-is-streaming.html">Prev</a> </td><th width="60%" align="center">Video2Linux devices</th><td width="20%" align="right"> <a accesskey="n" href="API-vb2-is-busy.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-vb2-fileio-is-active"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>vb2_fileio_is_active — 
2     return true if fileio is active.
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">bool <b class="fsfunc">vb2_fileio_is_active </b>(</code></td><td><a class="link" href="API-struct-vb2-queue.html" title="struct vb2_queue">struct vb2_queue</a> * <var class="pdparam">q</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="id-1.8.2.96.5"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>q</code></em></span></dt><dd><p>
4     videobuf queue
5    </p></dd></dl></div></div><div class="refsect1"><a name="id-1.8.2.96.6"></a><h2>Description</h2><p>
6   This returns true if <code class="function">read</code> or <code class="function">write</code> is used to stream the data
7   as opposed to stream I/O. This is almost never an important distinction,
8   except in rare cases. One such case is that using <code class="function">read</code> or <code class="function">write</code> to
9   stream a format using V4L2_FIELD_ALTERNATE is not allowed since there
10   is no way you can pass the field information of each buffer to/from
11   userspace. A driver that supports this field format should check for
12   this in the queue_setup op and reject it if this function returns true.
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