1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Some Hafta's</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="pci-resource.html" title="Chapter&#160;4.&#160;PCI Resource Management"><link rel="prev" href="pci-resource.html" title="Chapter&#160;4.&#160;PCI Resource Management"><link rel="next" href="pci-resource-resource-allocation.html" title="Resource Allocation"></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">Some Hafta's</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="pci-resource.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;4.&#160;PCI Resource Management</th><td width="20%" align="right">&#160;<a accesskey="n" href="pci-resource-resource-allocation.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="pci-resource-some-haftas"></a>Some Hafta's</h2></div></div></div><p>
2        The allocation of PCI resources is done in the
3      <code class="function">probe()</code> function, and usually an extra
4      <code class="function">xxx_create()</code> function is written for this
5      purpose.
6      </p><p>
7        In the case of PCI devices, you first have to call
8      the <code class="function">pci_enable_device()</code> function before
9      allocating resources. Also, you need to set the proper PCI DMA
10      mask to limit the accessed I/O range. In some cases, you might
11      need to call <code class="function">pci_set_master()</code> function,
12      too.
13      </p><p>
14        Suppose the 28bit mask, and the code to be added would be like:
15
16        </p><div class="informalexample"><pre class="programlisting">
17
18  err = pci_enable_device(pci);
19  if (err &lt; 0)
20          return err;
21  if (pci_set_dma_mask(pci, DMA_BIT_MASK(28)) &lt; 0 ||
22      pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(28)) &lt; 0) {
23          printk(KERN_ERR "error to set 28bit mask DMA\n");
24          pci_disable_device(pci);
25          return -ENXIO;
26  }
27  
28
29          </pre></div><p>
30      </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pci-resource.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="pci-resource.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="pci-resource-resource-allocation.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter&#160;4.&#160;PCI Resource Management&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;Resource Allocation</td></tr></table></div></body></html>
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