linux_dsm_epyc7002/Documentation/DocBook/media/v4l/vidioc-querystd.xml
Hans Verkuil 663dc7f3a0 [media] DocBook: document when to return ENODATA
ENODATA should be returned if the API used for getting, changing, querying
or enumerating the current video timings is not supported by the current input
or output.
This was decided during the 2012 Media Workshop.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-09-26 09:46:39 -03:00

75 lines
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<refentry id="vidioc-querystd">
<refmeta>
<refentrytitle>ioctl VIDIOC_QUERYSTD</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_QUERYSTD</refname>
<refpurpose>Sense the video standard received by the current
input</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>v4l2_std_id *<parameter>argp</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>fd</parameter></term>
<listitem>
<para>&fd;</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>request</parameter></term>
<listitem>
<para>VIDIOC_QUERYSTD</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>The hardware may be able to detect the current video
standard automatically. To do so, applications call <constant>
VIDIOC_QUERYSTD</constant> with a pointer to a &v4l2-std-id; type. The
driver stores here a set of candidates, this can be a single flag or a
set of supported standards if for example the hardware can only
distinguish between 50 and 60 Hz systems. When detection is not
possible or fails, the set must contain all standards supported by the
current video input or output.</para>
</refsect1>
<refsect1>
&return-value;
<variablelist>
<varlistentry>
<term><errorcode>ENODATA</errorcode></term>
<listitem>
<para>Standard video timings are not supported for this input or output.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>