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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>Chapter 5. __do_IRQ entry point</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux generic IRQ handling" /><link rel="up" href="index.html" title="Linux generic IRQ handling" /><link rel="prev" href="ch04s04.html" title="Chiplevel hardware encapsulation" /><link rel="next" href="ch06.html" title="Chapter 6. Locking on SMP" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 5. __do_IRQ entry point</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch04s04.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ch06.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter 5. __do_IRQ entry point"><div class="titlepage"><div><div><h2 class="title"><a id="doirq"></a>Chapter 5. __do_IRQ entry point</h2></div></div></div><p>
The original implementation __do_IRQ() is an alternative entry
point for all types of interrupts.
</p><p>
This handler turned out to be not suitable for all
interrupt hardware and was therefore reimplemented with split
functionality for egde/level/simple/percpu interrupts. This is not
only a functional optimization. It also shortens code paths for
interrupts.
</p><p>
To make use of the split implementation, replace the call to
__do_IRQ by a call to desc->chip->handle_irq() and associate
the appropriate handler function to desc->chip->handle_irq().
In most cases the generic handler implementations should
be sufficient.
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