Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.
1 <refentry id="vidioc-subdev-g-frame-interval"> 2 <refmeta> 3 <refentrytitle>ioctl VIDIOC_SUBDEV_G_FRAME_INTERVAL, VIDIOC_SUBDEV_S_FRAME_INTERVAL</refentrytitle> 4 &manvol; 5 </refmeta> 6 7 <refnamediv> 8 <refname>VIDIOC_SUBDEV_G_FRAME_INTERVAL</refname> 9 <refname>VIDIOC_SUBDEV_S_FRAME_INTERVAL</refname> 10 <refpurpose>Get or set the frame interval on a subdev pad</refpurpose> 11 </refnamediv> 12 13 <refsynopsisdiv> 14 <funcsynopsis> 15 <funcprototype> 16 <funcdef>int <function>ioctl</function></funcdef> 17 <paramdef>int <parameter>fd</parameter></paramdef> 18 <paramdef>int <parameter>request</parameter></paramdef> 19 <paramdef>struct v4l2_subdev_frame_interval *<parameter>argp</parameter> 20 </paramdef> 21 </funcprototype> 22 </funcsynopsis> 23 </refsynopsisdiv> 24 25 <refsect1> 26 <title>Arguments</title> 27 28 <variablelist> 29 <varlistentry> 30 <term><parameter>fd</parameter></term> 31 <listitem> 32 <para>&fd;</para> 33 </listitem> 34 </varlistentry> 35 <varlistentry> 36 <term><parameter>request</parameter></term> 37 <listitem> 38 <para>VIDIOC_SUBDEV_G_FRAME_INTERVAL, VIDIOC_SUBDEV_S_FRAME_INTERVAL</para> 39 </listitem> 40 </varlistentry> 41 <varlistentry> 42 <term><parameter>argp</parameter></term> 43 <listitem> 44 <para></para> 45 </listitem> 46 </varlistentry> 47 </variablelist> 48 </refsect1> 49 50 <refsect1> 51 <title>Description</title> 52 53 <para>These ioctls are used to get and set the frame interval at specific 54 subdev pads in the image pipeline. The frame interval only makes sense for 55 sub-devices that can control the frame period on their own. This includes, 56 for instance, image sensors and TV tuners. Sub-devices that don't support 57 frame intervals must not implement these ioctls.</para> 58 59 <para>To retrieve the current frame interval applications set the 60 <structfield>pad</structfield> field of a &v4l2-subdev-frame-interval; to 61 the desired pad number as reported by the media controller API. When they 62 call the <constant>VIDIOC_SUBDEV_G_FRAME_INTERVAL</constant> ioctl with a 63 pointer to this structure the driver fills the members of the 64 <structfield>interval</structfield> field.</para> 65 66 <para>To change the current frame interval applications set both the 67 <structfield>pad</structfield> field and all members of the 68 <structfield>interval</structfield> field. When they call the 69 <constant>VIDIOC_SUBDEV_S_FRAME_INTERVAL</constant> ioctl with a pointer to 70 this structure the driver verifies the requested interval, adjusts it based 71 on the hardware capabilities and configures the device. Upon return the 72 &v4l2-subdev-frame-interval; contains the current frame interval as would be 73 returned by a <constant>VIDIOC_SUBDEV_G_FRAME_INTERVAL</constant> call. 74 </para> 75 76 <para>Drivers must not return an error solely because the requested interval 77 doesn't match the device capabilities. They must instead modify the interval 78 to match what the hardware can provide. The modified interval should be as 79 close as possible to the original request.</para> 80 81 <para>Sub-devices that support the frame interval ioctls should implement 82 them on a single pad only. Their behaviour when supported on multiple pads 83 of the same sub-device is not defined.</para> 84 85 <table pgwide="1" frame="none" id="v4l2-subdev-frame-interval"> 86 <title>struct <structname>v4l2_subdev_frame_interval</structname></title> 87 <tgroup cols="3"> 88 &cs-str; 89 <tbody valign="top"> 90 <row> 91 <entry>__u32</entry> 92 <entry><structfield>pad</structfield></entry> 93 <entry>Pad number as reported by the media controller API.</entry> 94 </row> 95 <row> 96 <entry>&v4l2-fract;</entry> 97 <entry><structfield>interval</structfield></entry> 98 <entry>Period, in seconds, between consecutive video frames.</entry> 99 </row> 100 <row> 101 <entry>__u32</entry> 102 <entry><structfield>reserved</structfield>[9]</entry> 103 <entry>Reserved for future extensions. Applications and drivers must 104 set the array to zero.</entry> 105 </row> 106 </tbody> 107 </tgroup> 108 </table> 109 </refsect1> 110 111 <refsect1> 112 &return-value; 113 114 <variablelist> 115 <varlistentry> 116 <term><errorcode>EBUSY</errorcode></term> 117 <listitem> 118 <para>The frame interval can't be changed because the pad is currently 119 busy. This can be caused, for instance, by an active video stream on 120 the pad. The ioctl must not be retried without performing another 121 action to fix the problem first. Only returned by 122 <constant>VIDIOC_SUBDEV_S_FRAME_INTERVAL</constant></para> 123 </listitem> 124 </varlistentry> 125 <varlistentry> 126 <term><errorcode>EINVAL</errorcode></term> 127 <listitem> 128 <para>The &v4l2-subdev-frame-interval; <structfield>pad</structfield> 129 references a non-existing pad, or the pad doesn't support frame 130 intervals.</para> 131 </listitem> 132 </varlistentry> 133 </variablelist> 134 </refsect1> 135 </refentry>
