Documentation/DocBook/media/v4l/media-ioc-enum-entities.xml

   1 <refentry id="media-ioc-enum-entities">
   2   <refmeta>
   3     <refentrytitle>ioctl MEDIA_IOC_ENUM_ENTITIES</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>MEDIA_IOC_ENUM_ENTITIES</refname>
   9     <refpurpose>Enumerate entities and their properties</refpurpose>
  10   </refnamediv>
  11
  12   <refsynopsisdiv>
  13     <funcsynopsis>
  14       <funcprototype>
  15         <funcdef>int <function>ioctl</function></funcdef>
  16         <paramdef>int <parameter>fd</parameter></paramdef>
  17         <paramdef>int <parameter>request</parameter></paramdef>
  18         <paramdef>struct media_entity_desc *<parameter>argp</parameter></paramdef>
  19       </funcprototype>
  20     </funcsynopsis>
  21   </refsynopsisdiv>
  22
  23   <refsect1>
  24     <title>Arguments</title>
  25
  26     <variablelist>
  27       <varlistentry>
  28         <term><parameter>fd</parameter></term>
  29         <listitem>
  30           <para>File descriptor returned by
  31           <link linkend='media-func-open'><function>open()</function></link>.</para>
  32         </listitem>
  33       </varlistentry>
  34       <varlistentry>
  35         <term><parameter>request</parameter></term>
  36         <listitem>
  37           <para>MEDIA_IOC_ENUM_ENTITIES</para>
  38         </listitem>
  39       </varlistentry>
  40       <varlistentry>
  41         <term><parameter>argp</parameter></term>
  42         <listitem>
  43           <para></para>
  44         </listitem>
  45       </varlistentry>
  46     </variablelist>
  47   </refsect1>
  48
  49   <refsect1>
  50     <title>Description</title>
  51     <para>To query the attributes of an entity, applications set the id field
  52     of a &media-entity-desc; structure and call the MEDIA_IOC_ENUM_ENTITIES
  53     ioctl with a pointer to this structure. The driver fills the rest of the
  54     structure or returns an &EINVAL; when the id is invalid.</para>
  55     <para>Entities can be enumerated by or'ing the id with the
  56     <constant>MEDIA_ENT_ID_FLAG_NEXT</constant> flag. The driver will return
  57     information about the entity with the smallest id strictly larger than the
  58     requested one ('next entity'), or the &EINVAL; if there is none.</para>
  59     <para>Entity IDs can be non-contiguous. Applications must
  60     <emphasis>not</emphasis> try to enumerate entities by calling
  61     MEDIA_IOC_ENUM_ENTITIES with increasing id's until they get an error.</para>
  62     <para>Two or more entities that share a common non-zero
  63     <structfield>group_id</structfield> value are considered as logically
  64     grouped. Groups are used to report
  65     <itemizedlist>
  66       <listitem><para>ALSA, VBI and video nodes that carry the same media
  67       stream</para></listitem>
  68       <listitem><para>lens and flash controllers associated with a sensor</para></listitem>
  69     </itemizedlist>
  70     </para>
  71
  72     <table pgwide="1" frame="none" id="media-entity-desc">
  73       <title>struct <structname>media_entity_desc</structname></title>
  74       <tgroup cols="5">
  75         <colspec colname="c1" />
  76         <colspec colname="c2" />
  77         <colspec colname="c3" />
  78         <colspec colname="c4" />
  79         <colspec colname="c5" />
  80         <tbody valign="top">
  81           <row>
  82             <entry>__u32</entry>
  83             <entry><structfield>id</structfield></entry>
  84             <entry></entry>
  85             <entry></entry>
  86             <entry>Entity id, set by the application. When the id is or'ed with
  87             <constant>MEDIA_ENT_ID_FLAG_NEXT</constant>, the driver clears the
  88             flag and returns the first entity with a larger id.</entry>
  89           </row>
  90           <row>
  91             <entry>char</entry>
  92             <entry><structfield>name</structfield>[32]</entry>
  93             <entry></entry>
  94             <entry></entry>
  95             <entry>Entity name as an UTF-8 NULL-terminated string.</entry>
  96           </row>
  97           <row>
  98             <entry>__u32</entry>
  99             <entry><structfield>type</structfield></entry>
 100             <entry></entry>
 101             <entry></entry>
 102             <entry>Entity type, see <xref linkend="media-entity-type" /> for details.</entry>
 103           </row>
 104           <row>
 105             <entry>__u32</entry>
 106             <entry><structfield>revision</structfield></entry>
 107             <entry></entry>
 108             <entry></entry>
 109             <entry>Entity revision in a driver/hardware specific format.</entry>
 110           </row>
 111           <row>
 112             <entry>__u32</entry>
 113             <entry><structfield>flags</structfield></entry>
 114             <entry></entry>
 115             <entry></entry>
 116             <entry>Entity flags, see <xref linkend="media-entity-flag" /> for details.</entry>
 117           </row>
 118           <row>
 119             <entry>__u32</entry>
 120             <entry><structfield>group_id</structfield></entry>
 121             <entry></entry>
 122             <entry></entry>
 123             <entry>Entity group ID</entry>
 124           </row>
 125           <row>
 126             <entry>__u16</entry>
 127             <entry><structfield>pads</structfield></entry>
 128             <entry></entry>
 129             <entry></entry>
 130             <entry>Number of pads</entry>
 131           </row>
 132           <row>
 133             <entry>__u16</entry>
 134             <entry><structfield>links</structfield></entry>
 135             <entry></entry>
 136             <entry></entry>
 137             <entry>Total number of outbound links. Inbound links are not counted
 138             in this field.</entry>
 139           </row>
 140           <row>
 141             <entry>union</entry>
 142           </row>
 143           <row>
 144             <entry></entry>
 145             <entry>struct</entry>
 146             <entry><structfield>dev</structfield></entry>
 147             <entry></entry>
 148             <entry>Valid for (sub-)devices that create a single device node.</entry>
 149           </row>
 150           <row>
 151             <entry></entry>
 152             <entry></entry>
 153             <entry>__u32</entry>
 154             <entry><structfield>major</structfield></entry>
 155             <entry>Device node major number.</entry>
 156           </row>
 157           <row>
 158             <entry></entry>
 159             <entry></entry>
 160             <entry>__u32</entry>
 161             <entry><structfield>minor</structfield></entry>
 162             <entry>Device node minor number.</entry>
 163           </row>
 164           <row>
 165             <entry></entry>
 166             <entry>__u8</entry>
 167             <entry><structfield>raw</structfield>[184]</entry>
 168             <entry></entry>
 169             <entry></entry>
 170           </row>
 171         </tbody>
 172       </tgroup>
 173     </table>
 174
 175     <table frame="none" pgwide="1" id="media-entity-type">
 176       <title>Media entity types</title>
 177       <tgroup cols="2">
 178         <colspec colname="c1"/>
 179         <colspec colname="c2"/>
 180         <tbody valign="top">
 181           <row>
 182             <entry><constant>MEDIA_ENT_T_DEVNODE</constant></entry>
 183             <entry>Unknown device node</entry>
 184           </row>
 185           <row>
 186             <entry><constant>MEDIA_ENT_T_V4L2_VIDEO</constant></entry>
 187             <entry>V4L video, radio or vbi device node</entry>
 188           </row>
 189           <row>
 190             <entry><constant>MEDIA_ENT_T_DEVNODE_FB</constant></entry>
 191             <entry>Frame buffer device node</entry>
 192           </row>
 193           <row>
 194             <entry><constant>MEDIA_ENT_T_DEVNODE_ALSA</constant></entry>
 195             <entry>ALSA card</entry>
 196           </row>
 197           <row>
 198             <entry><constant>MEDIA_ENT_T_DEVNODE_DVB_FE</constant></entry>
 199             <entry>DVB frontend devnode</entry>
 200           </row>
 201           <row>
 202             <entry><constant>MEDIA_ENT_T_DEVNODE_DVB_DEMUX</constant></entry>
 203             <entry>DVB demux devnode</entry>
 204           </row>
 205           <row>
 206             <entry><constant>MEDIA_ENT_T_DEVNODE_DVB_DVR</constant></entry>
 207             <entry>DVB DVR devnode</entry>
 208           </row>
 209           <row>
 210             <entry><constant>MEDIA_ENT_T_DEVNODE_DVB_CA</constant></entry>
 211             <entry>DVB CAM devnode</entry>
 212           </row>
 213           <row>
 214             <entry><constant>MEDIA_ENT_T_DEVNODE_DVB_NET</constant></entry>
 215             <entry>DVB network devnode</entry>
 216           </row>
 217           <row>
 218             <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV</constant></entry>
 219             <entry>Unknown V4L sub-device</entry>
 220           </row>
 221           <row>
 222             <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_SENSOR</constant></entry>
 223             <entry>Video sensor</entry>
 224           </row>
 225           <row>
 226             <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_FLASH</constant></entry>
 227             <entry>Flash controller</entry>
 228           </row>
 229           <row>
 230             <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_LENS</constant></entry>
 231             <entry>Lens controller</entry>
 232           </row>
 233           <row>
 234             <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_DECODER</constant></entry>
 235             <entry>Video decoder, the basic function of the video decoder is to
 236             accept analogue video from a wide variety of sources such as
 237             broadcast, DVD players, cameras and video cassette recorders, in
 238             either NTSC, PAL or HD format and still occasionally SECAM, separate
 239             it into its component parts, luminance and chrominance, and output
 240             it in some digital video standard, with appropriate embedded timing
 241             signals.</entry>
 242           </row>
 243           <row>
 244             <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_TUNER</constant></entry>
 245             <entry>TV and/or radio tuner</entry>
 246           </row>
 247         </tbody>
 248       </tgroup>
 249     </table>
 250
 251     <table frame="none" pgwide="1" id="media-entity-flag">
 252       <title>Media entity flags</title>
 253       <tgroup cols="2">
 254         <colspec colname="c1"/>
 255         <colspec colname="c2"/>
 256         <tbody valign="top">
 257           <row>
 258             <entry><constant>MEDIA_ENT_FL_DEFAULT</constant></entry>
 259             <entry>Default entity for its type. Used to discover the default
 260             audio, VBI and video devices, the default camera sensor, ...</entry>
 261           </row>
 262         </tbody>
 263       </tgroup>
 264     </table>
 265   </refsect1>
 266
 267   <refsect1>
 268     &return-value;
 269
 270     <variablelist>
 271       <varlistentry>
 272         <term><errorcode>EINVAL</errorcode></term>
 273         <listitem>
 274           <para>The &media-entity-desc; <structfield>id</structfield> references
 275           a non-existing entity.</para>
 276         </listitem>
 277       </varlistentry>
 278     </variablelist>
 279   </refsect1>
 280 </refentry>