1<refentry id="vidioc-subdev-enum-frame-size">
2  <refmeta>
3    <refentrytitle>ioctl VIDIOC_SUBDEV_ENUM_FRAME_SIZE</refentrytitle>
4    &manvol;
5  </refmeta>
6
7  <refnamediv>
8    <refname>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</refname>
9    <refpurpose>Enumerate media bus frame sizes</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 v4l2_subdev_frame_size_enum *
19	<parameter>argp</parameter></paramdef>
20      </funcprototype>
21    </funcsynopsis>
22  </refsynopsisdiv>
23
24  <refsect1>
25    <title>Arguments</title>
26
27    <variablelist>
28      <varlistentry>
29	<term><parameter>fd</parameter></term>
30	<listitem>
31	  <para>&fd;</para>
32	</listitem>
33      </varlistentry>
34      <varlistentry>
35	<term><parameter>request</parameter></term>
36	<listitem>
37	  <para>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</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
52    <note>
53      <title>Experimental</title>
54      <para>This is an <link linkend="experimental">experimental</link>
55      interface and may change in the future.</para>
56    </note>
57
58    <para>This ioctl allows applications to enumerate all frame sizes
59    supported by a sub-device on the given pad for the given media bus format.
60    Supported formats can be retrieved with the &VIDIOC-SUBDEV-ENUM-MBUS-CODE;
61    ioctl.</para>
62
63    <para>To enumerate frame sizes applications initialize the
64    <structfield>pad</structfield>, <structfield>which</structfield> ,
65    <structfield>code</structfield> and <structfield>index</structfield>
66    fields of the &v4l2-subdev-mbus-code-enum; and call the
67    <constant>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</constant> ioctl with a pointer to
68    the structure. Drivers fill the minimum and maximum frame sizes or return
69    an &EINVAL; if one of the input parameters is invalid.</para>
70
71    <para>Sub-devices that only support discrete frame sizes (such as most
72    sensors) will return one or more frame sizes with identical minimum and
73    maximum values.</para>
74
75    <para>Not all possible sizes in given [minimum, maximum] ranges need to be
76    supported. For instance, a scaler that uses a fixed-point scaling ratio
77    might not be able to produce every frame size between the minimum and
78    maximum values. Applications must use the &VIDIOC-SUBDEV-S-FMT; ioctl to
79    try the sub-device for an exact supported frame size.</para>
80
81    <para>Available frame sizes may depend on the current 'try' formats at other
82    pads of the sub-device, as well as on the current active links and the
83    current values of V4L2 controls. See &VIDIOC-SUBDEV-G-FMT; for more
84    information about try formats.</para>
85
86    <table pgwide="1" frame="none" id="v4l2-subdev-frame-size-enum">
87      <title>struct <structname>v4l2_subdev_frame_size_enum</structname></title>
88      <tgroup cols="3">
89	&cs-str;
90	<tbody valign="top">
91	  <row>
92	    <entry>__u32</entry>
93	    <entry><structfield>index</structfield></entry>
94	    <entry>Number of the format in the enumeration, set by the
95	    application.</entry>
96	  </row>
97	  <row>
98	    <entry>__u32</entry>
99	    <entry><structfield>pad</structfield></entry>
100	    <entry>Pad number as reported by the media controller API.</entry>
101	  </row>
102	  <row>
103	    <entry>__u32</entry>
104	    <entry><structfield>code</structfield></entry>
105	    <entry>The media bus format code, as defined in
106	    <xref linkend="v4l2-mbus-format" />.</entry>
107	  </row>
108	  <row>
109	    <entry>__u32</entry>
110	    <entry><structfield>min_width</structfield></entry>
111	    <entry>Minimum frame width, in pixels.</entry>
112	  </row>
113	  <row>
114	    <entry>__u32</entry>
115	    <entry><structfield>max_width</structfield></entry>
116	    <entry>Maximum frame width, in pixels.</entry>
117	  </row>
118	  <row>
119	    <entry>__u32</entry>
120	    <entry><structfield>min_height</structfield></entry>
121	    <entry>Minimum frame height, in pixels.</entry>
122	  </row>
123	  <row>
124	    <entry>__u32</entry>
125	    <entry><structfield>max_height</structfield></entry>
126	    <entry>Maximum frame height, in pixels.</entry>
127	  </row>
128	  <row>
129	    <entry>__u32</entry>
130	    <entry><structfield>which</structfield></entry>
131	    <entry>Frame sizes to be enumerated, from &v4l2-subdev-format-whence;.</entry>
132	  </row>
133	  <row>
134	    <entry>__u32</entry>
135	    <entry><structfield>reserved</structfield>[8]</entry>
136	    <entry>Reserved for future extensions. Applications and drivers must
137	    set the array to zero.</entry>
138	  </row>
139	</tbody>
140      </tgroup>
141    </table>
142  </refsect1>
143
144  <refsect1>
145    &return-value;
146
147    <variablelist>
148      <varlistentry>
149	<term><errorcode>EINVAL</errorcode></term>
150	<listitem>
151	  <para>The &v4l2-subdev-frame-size-enum; <structfield>pad</structfield>
152	  references a non-existing pad, the <structfield>code</structfield> is
153	  invalid for the given pad or the <structfield>index</structfield>
154	  field is out of bounds.</para>
155	</listitem>
156      </varlistentry>
157    </variablelist>
158  </refsect1>
159</refentry>
160