linux-vybrid_public/Documentation/DocBook/v4l/vidioc-log-status.xml

<refentry id="vidioc-log-status">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_LOG_STATUS</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_LOG_STATUS</refname>
    <refpurpose>Log driver status information</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>As the video/audio devices become more complicated it
becomes harder to debug problems. When this ioctl is called the driver
will output the current device status to the kernel log. This is
particular useful when dealing with problems like no sound, no video
and incorrectly tuned channels. Also many modern devices autodetect
video and audio standards and this ioctl will report what the device
thinks what the standard is. Mismatches may give an indication where
the problem is.</para>

    <para>This ioctl is optional and not all drivers support it. It
was introduced in Linux 2.6.15.</para>
  </refsect1>

  <refsect1>
    &return-value;

    <variablelist>
      <varlistentry>
	<term><errorcode>EINVAL</errorcode></term>
	<listitem>
	  <para>The driver does not support this ioctl.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
</refentry>

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