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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>blk_queue_update_dma_alignment</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="The Linux Kernel API" /><link rel="up" href="ch14.html" title="Chapter 14. Block Devices" /><link rel="prev" href="re562.html" title="blk_queue_dma_alignment" /><link rel="next" href="re564.html" title="blk_execute_rq_nowait" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>blk_queue_update_dma_alignment</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re562.html">Prev</a> </td><th width="60%" align="center">Chapter 14. Block Devices</th><td width="20%" align="right"> <a accesskey="n" href="re564.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="blk_queue_update_dma_alignment"><a id="API-blk-queue-update-dma-alignment"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>blk_queue_update_dma_alignment —
update dma length and memory alignment
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">blk_queue_update_dma_alignment </b>(</code></td><td>struct request_queue * <var class="pdparam">q</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">mask</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2705568"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>q</code></em></span></dt><dd><p>
the request queue for the device
</p></dd><dt><span class="term"><em class="parameter"><code>mask</code></em></span></dt><dd><p>
alignment mask
</p></dd></dl></div></div><div class="refsect1" title="description"><a id="id2705611"></a><h2>description</h2><p>
update required memory and length alignment for direct dma transactions.
If the requested alignment is larger than the current alignment, then
the current queue alignment is updated to the new value, otherwise it
is left alone. The design of this is to allow multiple objects
(driver, device, transport etc) to set their respective
alignments without having them interfere.
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