About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

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




Custom Search

Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.

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	
63	    <table pgwide="1" frame="none" id="media-entity-desc">
64	      <title>struct <structname>media_entity_desc</structname></title>
65	      <tgroup cols="5">
66		<colspec colname="c1" />
67		<colspec colname="c2" />
68		<colspec colname="c3" />
69		<colspec colname="c4" />
70		<colspec colname="c5" />
71		<tbody valign="top">
72		  <row>
73		    <entry>__u32</entry>
74		    <entry><structfield>id</structfield></entry>
75		    <entry></entry>
76		    <entry></entry>
77		    <entry>Entity id, set by the application. When the id is or'ed with
78		    <constant>MEDIA_ENT_ID_FLAG_NEXT</constant>, the driver clears the
79		    flag and returns the first entity with a larger id.</entry>
80		  </row>
81		  <row>
82		    <entry>char</entry>
83		    <entry><structfield>name</structfield>[32]</entry>
84		    <entry></entry>
85		    <entry></entry>
86		    <entry>Entity name as an UTF-8 NULL-terminated string.</entry>
87		  </row>
88		  <row>
89		    <entry>__u32</entry>
90		    <entry><structfield>type</structfield></entry>
91		    <entry></entry>
92		    <entry></entry>
93		    <entry>Entity type, see <xref linkend="media-entity-type" /> for details.</entry>
94		  </row>
95		  <row>
96		    <entry>__u32</entry>
97		    <entry><structfield>revision</structfield></entry>
98		    <entry></entry>
99		    <entry></entry>
100		    <entry>Entity revision. Always zero (obsolete)</entry>
101		  </row>
102		  <row>
103		    <entry>__u32</entry>
104		    <entry><structfield>flags</structfield></entry>
105		    <entry></entry>
106		    <entry></entry>
107		    <entry>Entity flags, see <xref linkend="media-entity-flag" /> for details.</entry>
108		  </row>
109		  <row>
110		    <entry>__u32</entry>
111		    <entry><structfield>group_id</structfield></entry>
112		    <entry></entry>
113		    <entry></entry>
114		    <entry>Entity group ID. Always zero (obsolete)</entry>
115		  </row>
116		  <row>
117		    <entry>__u16</entry>
118		    <entry><structfield>pads</structfield></entry>
119		    <entry></entry>
120		    <entry></entry>
121		    <entry>Number of pads</entry>
122		  </row>
123		  <row>
124		    <entry>__u16</entry>
125		    <entry><structfield>links</structfield></entry>
126		    <entry></entry>
127		    <entry></entry>
128		    <entry>Total number of outbound links. Inbound links are not counted
129		    in this field.</entry>
130		  </row>
131		  <row>
132		    <entry>union</entry>
133		  </row>
134		  <row>
135		    <entry></entry>
136		    <entry>struct</entry>
137		    <entry><structfield>dev</structfield></entry>
138		    <entry></entry>
139		    <entry>Valid for (sub-)devices that create a single device node.</entry>
140		  </row>
141		  <row>
142		    <entry></entry>
143		    <entry></entry>
144		    <entry>__u32</entry>
145		    <entry><structfield>major</structfield></entry>
146		    <entry>Device node major number.</entry>
147		  </row>
148		  <row>
149		    <entry></entry>
150		    <entry></entry>
151		    <entry>__u32</entry>
152		    <entry><structfield>minor</structfield></entry>
153		    <entry>Device node minor number.</entry>
154		  </row>
155		  <row>
156		    <entry></entry>
157		    <entry>__u8</entry>
158		    <entry><structfield>raw</structfield>[184]</entry>
159		    <entry></entry>
160		    <entry></entry>
161		  </row>
162		</tbody>
163	      </tgroup>
164	    </table>
165	  </refsect1>
166	
167	  <refsect1>
168	    &return-value;
169	
170	    <variablelist>
171	      <varlistentry>
172		<term><errorcode>EINVAL</errorcode></term>
173		<listitem>
174		  <para>The &media-entity-desc; <structfield>id</structfield> references
175		  a non-existing entity.</para>
176		</listitem>
177	      </varlistentry>
178	    </variablelist>
179	  </refsect1>
180	</refentry>
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.