1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>kfifo_dma_out_prepare</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The Linux Kernel API"><link rel="up" href="kfifo.html#idp1125154228" title="kfifo interface"><link rel="prev" href="API-kfifo-dma-in-finish.html" title="kfifo_dma_in_finish"><link rel="next" href="API-kfifo-dma-out-finish.html" title="kfifo_dma_out_finish"></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">kfifo_dma_out_prepare</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-kfifo-dma-in-finish.html">Prev</a>&#160;</td><th width="60%" align="center">kfifo interface</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-kfifo-dma-out-finish.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-kfifo-dma-out-prepare"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>kfifo_dma_out_prepare &#8212; 
2     setup a scatterlist for DMA output
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"> <b class="fsfunc">kfifo_dma_out_prepare </b>(</code></td><td> <var class="pdparam">fifo</var>, </td></tr><tr><td>&#160;</td><td> <var class="pdparam">sgl</var>, </td></tr><tr><td>&#160;</td><td> <var class="pdparam">nents</var>, </td></tr><tr><td>&#160;</td><td> <var class="pdparam">len</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1125416468"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>fifo</code></em></span></dt><dd><p>
4     address of the fifo to be used
5    </p></dd><dt><span class="term"><em class="parameter"><code>sgl</code></em></span></dt><dd><p>
6     pointer to the scatterlist array
7    </p></dd><dt><span class="term"><em class="parameter"><code>nents</code></em></span></dt><dd><p>
8     number of entries in the scatterlist array
9    </p></dd><dt><span class="term"><em class="parameter"><code>len</code></em></span></dt><dd><p>
10     number of elements to transfer
11    </p></dd></dl></div></div><div class="refsect1"><a name="idp1125421172"></a><h2>Description</h2><p>
12   This macro fills a scatterlist for DMA output which at most <em class="parameter"><code>len</code></em> bytes
13   to transfer.
14   It returns the number entries in the scatterlist array.
15   A zero means there is no space available and the scatterlist is not filled.
16   </p><p>
17
18   Note that with only one concurrent reader and one concurrent
19   writer, you don't need extra locking to use these macros.
20</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-kfifo-dma-in-finish.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="kfifo.html#idp1125154228">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-kfifo-dma-out-finish.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">kfifo_dma_in_finish</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">kfifo_dma_out_finish</span></td></tr></table></div></body></html>
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