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Mauro Carvalho Chehab677cb4b2015-12-12 10:56:13 -02001<refentry id="media-g-topology">
2 <refmeta>
3 <refentrytitle>ioctl MEDIA_IOC_G_TOPOLOGY</refentrytitle>
4 &manvol;
5 </refmeta>
6
7 <refnamediv>
8 <refname>MEDIA_IOC_G_TOPOLOGY</refname>
9 <refpurpose>Enumerate the graph topology and graph element 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_v2_topology *<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_G_TOPOLOGY</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>
Mauro Carvalho Chehab677cb4b2015-12-12 10:56:13 -020051 <para>The typical usage of this ioctl is to call it twice.
52 On the first call, the structure defined at &media-v2-topology; should
53 be zeroed. At return, if no errors happen, this ioctl will return the
54 <constant>topology_version</constant> and the total number of entities,
55 interfaces, pads and links.</para>
56 <para>Before the second call, the userspace should allocate arrays to
57 store the graph elements that are desired, putting the pointers to them
58 at the ptr_entities, ptr_interfaces, ptr_links and/or ptr_pads, keeping
59 the other values untouched.</para>
60 <para>If the <constant>topology_version</constant> remains the same, the
61 ioctl should fill the desired arrays with the media graph elements.</para>
62
63 <table pgwide="1" frame="none" id="media-v2-topology">
64 <title>struct <structname>media_v2_topology</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>__u64</entry>
74 <entry><structfield>topology_version</structfield></entry>
75 <entry></entry>
76 <entry></entry>
77 <entry>Version of the media graph topology. When the graph is
78 created, this field starts with zero. Every time a graph
79 element is added or removed, this field is
80 incremented.</entry>
81 </row>
82 <row>
83 <entry>__u64</entry>
84 <entry><structfield>num_entities</structfield></entry>
85 <entry></entry>
86 <entry></entry>
87 <entry>Number of entities in the graph</entry>
88 </row>
89 <row>
90 <entry>__u64</entry>
91 <entry><structfield>ptr_entities</structfield></entry>
92 <entry></entry>
93 <entry></entry>
94 <entry>A pointer to a memory area where the entities array
95 will be stored, converted to a 64-bits integer.
96 It can be zero. if zero, the ioctl won't store the
97 entities. It will just update
98 <constant>num_entities</constant></entry>
99 </row>
100 <row>
101 <entry>__u64</entry>
102 <entry><structfield>num_interfaces</structfield></entry>
103 <entry></entry>
104 <entry></entry>
105 <entry>Number of interfaces in the graph</entry>
106 </row>
107 <row>
108 <entry>__u64</entry>
109 <entry><structfield>ptr_interfaces</structfield></entry>
110 <entry></entry>
111 <entry></entry>
112 <entry>A pointer to a memory area where the interfaces array
113 will be stored, converted to a 64-bits integer.
114 It can be zero. if zero, the ioctl won't store the
115 interfaces. It will just update
116 <constant>num_interfaces</constant></entry>
117 </row>
118 <row>
119 <entry>__u64</entry>
120 <entry><structfield>num_pads</structfield></entry>
121 <entry></entry>
122 <entry></entry>
123 <entry>Total number of pads in the graph</entry>
124 </row>
125 <row>
126 <entry>__u64</entry>
127 <entry><structfield>ptr_pads</structfield></entry>
128 <entry></entry>
129 <entry></entry>
130 <entry>A pointer to a memory area where the pads array
131 will be stored, converted to a 64-bits integer.
132 It can be zero. if zero, the ioctl won't store the
133 pads. It will just update
134 <constant>num_pads</constant></entry>
135 </row>
136 <row>
137 <entry>__u64</entry>
138 <entry><structfield>num_links</structfield></entry>
139 <entry></entry>
140 <entry></entry>
141 <entry>Total number of data and interface links in the graph</entry>
142 </row>
143 <row>
144 <entry>__u64</entry>
145 <entry><structfield>ptr_links</structfield></entry>
146 <entry></entry>
147 <entry></entry>
148 <entry>A pointer to a memory area where the links array
149 will be stored, converted to a 64-bits integer.
150 It can be zero. if zero, the ioctl won't store the
151 links. It will just update
152 <constant>num_links</constant></entry>
153 </row>
154 </tbody>
155 </tgroup>
156 </table>
157
158 <table pgwide="1" frame="none" id="media-v2-entity">
159 <title>struct <structname>media_v2_entity</structname></title>
160 <tgroup cols="5">
161 <colspec colname="c1" />
162 <colspec colname="c2" />
163 <colspec colname="c3" />
164 <colspec colname="c4" />
165 <colspec colname="c5" />
166 <tbody valign="top">
167 <row>
168 <entry>__u32</entry>
169 <entry><structfield>id</structfield></entry>
170 <entry></entry>
171 <entry></entry>
172 <entry>Unique ID for the entity.</entry>
173 </row>
174 <row>
175 <entry>char</entry>
176 <entry><structfield>name</structfield>[64]</entry>
177 <entry></entry>
178 <entry></entry>
179 <entry>Entity name as an UTF-8 NULL-terminated string.</entry>
180 </row>
181 <row>
182 <entry>__u32</entry>
183 <entry><structfield>function</structfield></entry>
184 <entry></entry>
185 <entry></entry>
186 <entry>Entity main function, see <xref linkend="media-entity-type" /> for details.</entry>
187 </row>
188 <row>
189 <entry>__u32</entry>
190 <entry><structfield>reserved</structfield>[12]</entry>
191 <entry>Reserved for future extensions. Drivers and applications must
192 set this array to zero.</entry>
193 </row>
194 </tbody>
195 </tgroup>
196 </table>
197
198 <table pgwide="1" frame="none" id="media-v2-interface">
199 <title>struct <structname>media_v2_interface</structname></title>
200 <tgroup cols="5">
201 <colspec colname="c1" />
202 <colspec colname="c2" />
203 <colspec colname="c3" />
204 <colspec colname="c4" />
205 <colspec colname="c5" />
206 <tbody valign="top">
207 <row>
208 <entry>__u32</entry>
209 <entry><structfield>id</structfield></entry>
210 <entry></entry>
211 <entry></entry>
212 <entry>Unique ID for the interface.</entry>
213 </row>
214 <row>
215 <entry>__u32</entry>
216 <entry><structfield>intf_type</structfield></entry>
217 <entry></entry>
218 <entry></entry>
219 <entry>Interface type, see <xref linkend="media-intf-type" /> for details.</entry>
220 </row>
221 <row>
222 <entry>__u32</entry>
223 <entry><structfield>flags</structfield></entry>
224 <entry></entry>
225 <entry></entry>
226 <entry>Interface flags. Currently unused.</entry>
227 </row>
228 <row>
229 <entry>__u32</entry>
230 <entry><structfield>reserved</structfield>[9]</entry>
231 <entry></entry>
232 <entry></entry>
233 <entry>Reserved for future extensions. Drivers and applications must
234 set this array to zero.</entry>
235 </row>
236 <row>
237 <entry>struct media_v2_intf_devnode</entry>
238 <entry><structfield>devnode</structfield></entry>
239 <entry></entry>
240 <entry></entry>
241 <entry>Used only for device node interfaces. See <xref linkend="media-v2-intf-devnode" /> for details..</entry>
242 </row>
243 </tbody>
244 </tgroup>
245 </table>
246
247 <table pgwide="1" frame="none" id="media-v2-intf-devnode">
248 <title>struct <structname>media_v2_interface</structname></title>
249 <tgroup cols="5">
250 <colspec colname="c1" />
251 <colspec colname="c2" />
252 <colspec colname="c3" />
253 <colspec colname="c4" />
254 <colspec colname="c5" />
255 <tbody valign="top">
256 <row>
257 <entry>__u32</entry>
258 <entry><structfield>major</structfield></entry>
259 <entry></entry>
260 <entry></entry>
261 <entry>Device node major number.</entry>
262 </row>
263 <row>
264 <entry>__u32</entry>
265 <entry><structfield>minor</structfield></entry>
266 <entry></entry>
267 <entry></entry>
268 <entry>Device node minor number.</entry>
269 </row>
270 </tbody>
271 </tgroup>
272 </table>
273
274 <table pgwide="1" frame="none" id="media-v2-pad">
275 <title>struct <structname>media_v2_pad</structname></title>
276 <tgroup cols="5">
277 <colspec colname="c1" />
278 <colspec colname="c2" />
279 <colspec colname="c3" />
280 <colspec colname="c4" />
281 <colspec colname="c5" />
282 <tbody valign="top">
283 <row>
284 <entry>__u32</entry>
285 <entry><structfield>id</structfield></entry>
286 <entry></entry>
287 <entry></entry>
288 <entry>Unique ID for the pad.</entry>
289 </row>
290 <row>
291 <entry>__u32</entry>
292 <entry><structfield>entity_id</structfield></entry>
293 <entry></entry>
294 <entry></entry>
295 <entry>Unique ID for the entity where this pad belongs.</entry>
296 </row>
297 <row>
298 <entry>__u32</entry>
299 <entry><structfield>flags</structfield></entry>
300 <entry></entry>
301 <entry></entry>
302 <entry>Pad flags, see <xref linkend="media-pad-flag" /> for more details.</entry>
303 </row>
304 <row>
305 <entry>__u32</entry>
306 <entry><structfield>reserved</structfield>[9]</entry>
307 <entry></entry>
308 <entry></entry>
309 <entry>Reserved for future extensions. Drivers and applications must
310 set this array to zero.</entry>
311 </row>
312 </tbody>
313 </tgroup>
314 </table>
315
316 <table pgwide="1" frame="none" id="media-v2-link">
317 <title>struct <structname>media_v2_pad</structname></title>
318 <tgroup cols="5">
319 <colspec colname="c1" />
320 <colspec colname="c2" />
321 <colspec colname="c3" />
322 <colspec colname="c4" />
323 <colspec colname="c5" />
324 <tbody valign="top">
325 <row>
326 <entry>__u32</entry>
327 <entry><structfield>id</structfield></entry>
328 <entry></entry>
329 <entry></entry>
330 <entry>Unique ID for the pad.</entry>
331 </row>
332 <row>
333 <entry>__u32</entry>
334 <entry><structfield>source_id</structfield></entry>
335 <entry></entry>
336 <entry></entry>
337 <entry>
338 <para>On pad to pad links: unique ID for the source pad.</para>
339 <para>On interface to entity links: unique ID for the interface.</para>
340 </entry>
341 </row>
342 <row>
343 <entry>__u32</entry>
344 <entry><structfield>sink_id</structfield></entry>
345 <entry></entry>
346 <entry></entry>
347 <entry>
348 <para>On pad to pad links: unique ID for the sink pad.</para>
349 <para>On interface to entity links: unique ID for the entity.</para>
350 </entry>
351 </row>
352 <row>
353 <entry>__u32</entry>
354 <entry><structfield>flags</structfield></entry>
355 <entry></entry>
356 <entry></entry>
357 <entry>Link flags, see <xref linkend="media-link-flag" /> for more details.</entry>
358 </row>
359 <row>
360 <entry>__u32</entry>
361 <entry><structfield>reserved</structfield>[5]</entry>
362 <entry></entry>
363 <entry></entry>
364 <entry>Reserved for future extensions. Drivers and applications must
365 set this array to zero.</entry>
366 </row>
367 </tbody>
368 </tgroup>
369 </table>
370
371 </refsect1>
372
373 <refsect1>
374 &return-value;
375
376 <variablelist>
377 <varlistentry>
378 <term><errorcode>ENOSPC</errorcode></term>
379 <listitem>
380 <para>This is returned when either one or more of the num_entities,
381 num_interfaces, num_links or num_pads are non-zero and are smaller
382 than the actual number of elements inside the graph. This may happen
383 if the <constant>topology_version</constant> changed when compared
384 to the last time this ioctl was called. Userspace should usually
385 free the area for the pointers, zero the struct elements and call
386 this ioctl again.</para>
387 </listitem>
388 </varlistentry>
389 </variablelist>
390 </refsect1>
391</refentry>