1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>VBlank event handling</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Linux DRM Developer's Guide"><link rel="up" href="drmExternals.html" title="Chapter&#160;3.&#160;Userland interfaces"><link rel="prev" href="drmExternals.html" title="Chapter&#160;3.&#160;Userland interfaces"><link rel="next" href="drmDrivers.html" title="Part&#160;II.&#160;DRM Drivers"></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">VBlank event handling</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="drmExternals.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;3.&#160;Userland interfaces</th><td width="20%" align="right">&#160;<a accesskey="n" href="drmDrivers.html">Next</a></td></tr></table><hr></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1127677356"></a>VBlank event handling</h2></div></div></div><p>
2        The DRM core exposes two vertical blank related ioctls:
3        </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">DRM_IOCTL_WAIT_VBLANK</span></dt><dd><p>
4                This takes a struct drm_wait_vblank structure as its argument,
5                and it is used to block or request a signal when a specified
6                vblank event occurs.
7              </p></dd><dt><span class="term">DRM_IOCTL_MODESET_CTL</span></dt><dd><p>
8		This was only used for user-mode-settind drivers around
9		modesetting changes to allow the kernel to update the vblank
10		interrupt after mode setting, since on many devices the vertical
11		blank counter is reset to 0 at some point during modeset. Modern
12		drivers should not call this any more since with kernel mode
13		setting it is a no-op.
14              </p></dd></dl></div><p>
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