155 lines
4.9 KiB
XML
155 lines
4.9 KiB
XML
<refentry id="vidioc-subdev-enum-frame-size">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_SUBDEV_ENUM_FRAME_SIZE</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</refname>
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<refpurpose>Enumerate media bus frame sizes</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct v4l2_subdev_frame_size_enum *
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<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><parameter>fd</parameter></term>
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<listitem>
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<para>&fd;</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>request</parameter></term>
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<listitem>
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<para>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>argp</parameter></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<note>
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<title>Experimental</title>
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<para>This is an <link linkend="experimental">experimental</link>
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interface and may change in the future.</para>
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</note>
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<para>This ioctl allows applications to enumerate all frame sizes
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supported by a sub-device on the given pad for the given media bus format.
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Supported formats can be retrieved with the &VIDIOC-SUBDEV-ENUM-MBUS-CODE;
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ioctl.</para>
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<para>To enumerate frame sizes applications initialize the
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<structfield>pad</structfield>, <structfield>code</structfield> and
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<structfield>index</structfield> fields of the
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&v4l2-subdev-mbus-code-enum; and call the
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<constant>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</constant> ioctl with a pointer to
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the structure. Drivers fill the minimum and maximum frame sizes or return
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an &EINVAL; if one of the input parameters is invalid.</para>
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<para>Sub-devices that only support discrete frame sizes (such as most
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sensors) will return one or more frame sizes with identical minimum and
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maximum values.</para>
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<para>Not all possible sizes in given [minimum, maximum] ranges need to be
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supported. For instance, a scaler that uses a fixed-point scaling ratio
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might not be able to produce every frame size between the minimum and
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maximum values. Applications must use the &VIDIOC-SUBDEV-S-FMT; ioctl to
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try the sub-device for an exact supported frame size.</para>
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<para>Available frame sizes may depend on the current 'try' formats at other
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pads of the sub-device, as well as on the current active links and the
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current values of V4L2 controls. See &VIDIOC-SUBDEV-G-FMT; for more
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information about try formats.</para>
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<table pgwide="1" frame="none" id="v4l2-subdev-frame-size-enum">
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<title>struct <structname>v4l2_subdev_frame_size_enum</structname></title>
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<tgroup cols="3">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>index</structfield></entry>
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<entry>Number of the format in the enumeration, set by the
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application.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>pad</structfield></entry>
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<entry>Pad number as reported by the media controller API.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>code</structfield></entry>
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<entry>The media bus format code, as defined in
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<xref linkend="v4l2-mbus-format" />.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>min_width</structfield></entry>
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<entry>Minimum frame width, in pixels.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>max_width</structfield></entry>
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<entry>Maximum frame width, in pixels.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>min_height</structfield></entry>
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<entry>Minimum frame height, in pixels.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>max_height</structfield></entry>
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<entry>Maximum frame height, in pixels.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[9]</entry>
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<entry>Reserved for future extensions. Applications and drivers must
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set the array to zero.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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&return-value;
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<variablelist>
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<varlistentry>
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<term><errorcode>EINVAL</errorcode></term>
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<listitem>
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<para>The &v4l2-subdev-frame-size-enum; <structfield>pad</structfield>
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references a non-existing pad, the <structfield>code</structfield> is
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invalid for the given pad or the <structfield>index</structfield>
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field is out of bounds.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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</refentry>
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