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1 <refentry id="media-ioc-enum-entities">
2 <refmeta>
3 <refentrytitle>ioctl MEDIA_IOC_ENUM_ENTITIES</refentrytitle>
4 &manvol;
5 </refmeta>
7 <refnamediv>
8 <refname>MEDIA_IOC_ENUM_ENTITIES</refname>
9 <refpurpose>Enumerate entities and their properties</refpurpose>
10 </refnamediv>
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>
23 <refsect1>
24 <title>Arguments</title>
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>
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>
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>v4l</structfield></entry>
147 <entry></entry>
148 <entry>Valid for V4L sub-devices and nodes only.</entry>
149 </row>
150 <row>
151 <entry></entry>
152 <entry></entry>
153 <entry>__u32</entry>
154 <entry><structfield>major</structfield></entry>
155 <entry>V4L device node major number. For V4L sub-devices with no
156 device node, set by the driver to 0.</entry>
157 </row>
158 <row>
159 <entry></entry>
160 <entry></entry>
161 <entry>__u32</entry>
162 <entry><structfield>minor</structfield></entry>
163 <entry>V4L device node minor number. For V4L sub-devices with no
164 device node, set by the driver to 0.</entry>
165 </row>
166 <row>
167 <entry></entry>
168 <entry>struct</entry>
169 <entry><structfield>fb</structfield></entry>
170 <entry></entry>
171 <entry>Valid for frame buffer nodes only.</entry>
172 </row>
173 <row>
174 <entry></entry>
175 <entry></entry>
176 <entry>__u32</entry>
177 <entry><structfield>major</structfield></entry>
178 <entry>Frame buffer device node major number.</entry>
179 </row>
180 <row>
181 <entry></entry>
182 <entry></entry>
183 <entry>__u32</entry>
184 <entry><structfield>minor</structfield></entry>
185 <entry>Frame buffer device node minor number.</entry>
186 </row>
187 <row>
188 <entry></entry>
189 <entry>struct</entry>
190 <entry><structfield>alsa</structfield></entry>
191 <entry></entry>
192 <entry>Valid for ALSA devices only.</entry>
193 </row>
194 <row>
195 <entry></entry>
196 <entry></entry>
197 <entry>__u32</entry>
198 <entry><structfield>card</structfield></entry>
199 <entry>ALSA card number</entry>
200 </row>
201 <row>
202 <entry></entry>
203 <entry></entry>
204 <entry>__u32</entry>
205 <entry><structfield>device</structfield></entry>
206 <entry>ALSA device number</entry>
207 </row>
208 <row>
209 <entry></entry>
210 <entry></entry>
211 <entry>__u32</entry>
212 <entry><structfield>subdevice</structfield></entry>
213 <entry>ALSA sub-device number</entry>
214 </row>
215 <row>
216 <entry></entry>
217 <entry>int</entry>
218 <entry><structfield>dvb</structfield></entry>
219 <entry></entry>
220 <entry>DVB card number</entry>
221 </row>
222 <row>
223 <entry></entry>
224 <entry>__u8</entry>
225 <entry><structfield>raw</structfield>[180]</entry>
226 <entry></entry>
227 <entry></entry>
228 </row>
229 </tbody>
230 </tgroup>
231 </table>
233 <table frame="none" pgwide="1" id="media-entity-type">
234 <title>Media entity types</title>
235 <tgroup cols="2">
236 <colspec colname="c1"/>
237 <colspec colname="c2"/>
238 <tbody valign="top">
239 <row>
240 <entry><constant>MEDIA_ENT_T_DEVNODE</constant></entry>
241 <entry>Unknown device node</entry>
242 </row>
243 <row>
244 <entry><constant>MEDIA_ENT_T_DEVNODE_V4L</constant></entry>
245 <entry>V4L video, radio or vbi device node</entry>
246 </row>
247 <row>
248 <entry><constant>MEDIA_ENT_T_DEVNODE_FB</constant></entry>
249 <entry>Frame buffer device node</entry>
250 </row>
251 <row>
252 <entry><constant>MEDIA_ENT_T_DEVNODE_ALSA</constant></entry>
253 <entry>ALSA card</entry>
254 </row>
255 <row>
256 <entry><constant>MEDIA_ENT_T_DEVNODE_DVB</constant></entry>
257 <entry>DVB card</entry>
258 </row>
259 <row>
260 <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV</constant></entry>
261 <entry>Unknown V4L sub-device</entry>
262 </row>
263 <row>
264 <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_SENSOR</constant></entry>
265 <entry>Video sensor</entry>
266 </row>
267 <row>
268 <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_FLASH</constant></entry>
269 <entry>Flash controller</entry>
270 </row>
271 <row>
272 <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_LENS</constant></entry>
273 <entry>Lens controller</entry>
274 </row>
275 </tbody>
276 </tgroup>
277 </table>
279 <table frame="none" pgwide="1" id="media-entity-flag">
280 <title>Media entity flags</title>
281 <tgroup cols="2">
282 <colspec colname="c1"/>
283 <colspec colname="c2"/>
284 <tbody valign="top">
285 <row>
286 <entry><constant>MEDIA_ENT_FL_DEFAULT</constant></entry>
287 <entry>Default entity for its type. Used to discover the default
288 audio, VBI and video devices, the default camera sensor, ...</entry>
289 </row>
290 </tbody>
291 </tgroup>
292 </table>
293 </refsect1>
295 <refsect1>
296 &return-value;
298 <variablelist>
299 <varlistentry>
300 <term><errorcode>EINVAL</errorcode></term>
301 <listitem>
302 <para>The &media-entity-desc; <structfield>id</structfield> references
303 a non-existing entity.</para>
304 </listitem>
305 </varlistentry>
306 </variablelist>
307 </refsect1>
308 </refentry>