308 lines
10 KiB
XML
308 lines
10 KiB
XML
|
<refentry id="vidioc-g-ext-ctrls">
|
||
|
|
<refmeta>
|
||
|
|
<refentrytitle>ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS,
|
||
|
|
VIDIOC_TRY_EXT_CTRLS</refentrytitle>
|
||
|
|
&manvol;
|
||
|
|
</refmeta>
|
||
|
|
|
||
|
|
<refnamediv>
|
||
|
|
<refname>VIDIOC_G_EXT_CTRLS</refname>
|
||
|
|
<refname>VIDIOC_S_EXT_CTRLS</refname>
|
||
|
|
<refname>VIDIOC_TRY_EXT_CTRLS</refname>
|
||
|
|
<refpurpose>Get or set the value of several controls, try control
|
||
|
|
values</refpurpose>
|
||
|
|
</refnamediv>
|
||
|
|
|
||
|
|
<refsynopsisdiv>
|
||
|
|
<funcsynopsis>
|
||
|
|
<funcprototype>
|
||
|
|
<funcdef>int <function>ioctl</function></funcdef>
|
||
|
|
<paramdef>int <parameter>fd</parameter></paramdef>
|
||
|
|
<paramdef>int <parameter>request</parameter></paramdef>
|
||
|
|
<paramdef>struct v4l2_ext_controls
|
||
|
|
*<parameter>argp</parameter></paramdef>
|
||
|
|
</funcprototype>
|
||
|
|
</funcsynopsis>
|
||
|
|
</refsynopsisdiv>
|
||
|
|
|
||
|
|
<refsect1>
|
||
|
|
<title>Arguments</title>
|
||
|
|
|
||
|
|
<variablelist>
|
||
|
|
<varlistentry>
|
||
|
|
<term><parameter>fd</parameter></term>
|
||
|
|
<listitem>
|
||
|
|
<para>&fd;</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><parameter>request</parameter></term>
|
||
|
|
<listitem>
|
||
|
|
<para>VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS,
|
||
|
|
VIDIOC_TRY_EXT_CTRLS</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><parameter>argp</parameter></term>
|
||
|
|
<listitem>
|
||
|
|
<para></para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
</variablelist>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
<refsect1>
|
||
|
|
<title>Description</title>
|
||
|
|
|
||
|
|
<para>These ioctls allow the caller to get or set multiple
|
||
|
|
controls atomically. Control IDs are grouped into control classes (see
|
||
|
|
<xref linkend="ctrl-class" />) and all controls in the control array
|
||
|
|
must belong to the same control class.</para>
|
||
|
|
|
||
|
|
<para>Applications must always fill in the
|
||
|
|
<structfield>count</structfield>,
|
||
|
|
<structfield>ctrl_class</structfield>,
|
||
|
|
<structfield>controls</structfield> and
|
||
|
|
<structfield>reserved</structfield> fields of &v4l2-ext-controls;, and
|
||
|
|
initialize the &v4l2-ext-control; array pointed to by the
|
||
|
|
<structfield>controls</structfield> fields.</para>
|
||
|
|
|
||
|
|
<para>To get the current value of a set of controls applications
|
||
|
|
initialize the <structfield>id</structfield>,
|
||
|
|
<structfield>size</structfield> and <structfield>reserved2</structfield> fields
|
||
|
|
of each &v4l2-ext-control; and call the
|
||
|
|
<constant>VIDIOC_G_EXT_CTRLS</constant> ioctl. String controls controls
|
||
|
|
must also set the <structfield>string</structfield> field.</para>
|
||
|
|
|
||
|
|
<para>If the <structfield>size</structfield> is too small to
|
||
|
|
receive the control result (only relevant for pointer-type controls
|
||
|
|
like strings), then the driver will set <structfield>size</structfield>
|
||
|
|
to a valid value and return an &ENOSPC;. You should re-allocate the
|
||
|
|
string memory to this new size and try again. It is possible that the
|
||
|
|
same issue occurs again if the string has grown in the meantime. It is
|
||
|
|
recommended to call &VIDIOC-QUERYCTRL; first and use
|
||
|
|
<structfield>maximum</structfield>+1 as the new <structfield>size</structfield>
|
||
|
|
value. It is guaranteed that that is sufficient memory.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
<para>To change the value of a set of controls applications
|
||
|
|
initialize the <structfield>id</structfield>, <structfield>size</structfield>,
|
||
|
|
<structfield>reserved2</structfield> and
|
||
|
|
<structfield>value/string</structfield> fields of each &v4l2-ext-control; and
|
||
|
|
call the <constant>VIDIOC_S_EXT_CTRLS</constant> ioctl. The controls
|
||
|
|
will only be set if <emphasis>all</emphasis> control values are
|
||
|
|
valid.</para>
|
||
|
|
|
||
|
|
<para>To check if a set of controls have correct values applications
|
||
|
|
initialize the <structfield>id</structfield>, <structfield>size</structfield>,
|
||
|
|
<structfield>reserved2</structfield> and
|
||
|
|
<structfield>value/string</structfield> fields of each &v4l2-ext-control; and
|
||
|
|
call the <constant>VIDIOC_TRY_EXT_CTRLS</constant> ioctl. It is up to
|
||
|
|
the driver whether wrong values are automatically adjusted to a valid
|
||
|
|
value or if an error is returned.</para>
|
||
|
|
|
||
|
|
<para>When the <structfield>id</structfield> or
|
||
|
|
<structfield>ctrl_class</structfield> is invalid drivers return an
|
||
|
|
&EINVAL;. When the value is out of bounds drivers can choose to take
|
||
|
|
the closest valid value or return an &ERANGE;, whatever seems more
|
||
|
|
appropriate. In the first case the new value is set in
|
||
|
|
&v4l2-ext-control;.</para>
|
||
|
|
|
||
|
|
<para>The driver will only set/get these controls if all control
|
||
|
|
values are correct. This prevents the situation where only some of the
|
||
|
|
controls were set/get. Only low-level errors (⪚ a failed i2c
|
||
|
|
command) can still cause this situation.</para>
|
||
|
|
|
||
|
|
<table pgwide="1" frame="none" id="v4l2-ext-control">
|
||
|
|
<title>struct <structname>v4l2_ext_control</structname></title>
|
||
|
|
<tgroup cols="4">
|
||
|
|
&cs-ustr;
|
||
|
|
<tbody valign="top">
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>id</structfield></entry>
|
||
|
|
<entry></entry>
|
||
|
|
<entry>Identifies the control, set by the
|
||
|
|
application.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>size</structfield></entry>
|
||
|
|
<entry></entry>
|
||
|
|
<entry>The total size in bytes of the payload of this
|
||
|
|
control. This is normally 0, but for pointer controls this should be
|
||
|
|
set to the size of the memory containing the payload, or that will
|
||
|
|
receive the payload. If <constant>VIDIOC_G_EXT_CTRLS</constant> finds
|
||
|
|
that this value is less than is required to store
|
||
|
|
the payload result, then it is set to a value large enough to store the
|
||
|
|
payload result and ENOSPC is returned. Note that for string controls
|
||
|
|
this <structfield>size</structfield> field should not be confused with the length of the string.
|
||
|
|
This field refers to the size of the memory that contains the string.
|
||
|
|
The actual <emphasis>length</emphasis> of the string may well be much smaller.
|
||
|
|
</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>reserved2</structfield>[1]</entry>
|
||
|
|
<entry></entry>
|
||
|
|
<entry>Reserved for future extensions. Drivers and
|
||
|
|
applications must set the array to zero.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>union</entry>
|
||
|
|
<entry>(anonymous)</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry></entry>
|
||
|
|
<entry>__s32</entry>
|
||
|
|
<entry><structfield>value</structfield></entry>
|
||
|
|
<entry>New value or current value.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry></entry>
|
||
|
|
<entry>__s64</entry>
|
||
|
|
<entry><structfield>value64</structfield></entry>
|
||
|
|
<entry>New value or current value.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry></entry>
|
||
|
|
<entry>char *</entry>
|
||
|
|
<entry><structfield>string</structfield></entry>
|
||
|
|
<entry>A pointer to a string.</entry>
|
||
|
|
</row>
|
||
|
|
</tbody>
|
||
|
|
</tgroup>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<table pgwide="1" frame="none" id="v4l2-ext-controls">
|
||
|
|
<title>struct <structname>v4l2_ext_controls</structname></title>
|
||
|
|
<tgroup cols="3">
|
||
|
|
&cs-str;
|
||
|
|
<tbody valign="top">
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>ctrl_class</structfield></entry>
|
||
|
|
<entry>The control class to which all controls belong, see
|
||
|
|
<xref linkend="ctrl-class" />.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>count</structfield></entry>
|
||
|
|
<entry>The number of controls in the controls array. May
|
||
|
|
also be zero.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>error_idx</structfield></entry>
|
||
|
|
<entry>Set by the driver in case of an error. It is the
|
||
|
|
index of the control causing the error or equal to 'count' when the
|
||
|
|
error is not associated with a particular control. Undefined when the
|
||
|
|
ioctl returns 0 (success).</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>reserved</structfield>[2]</entry>
|
||
|
|
<entry>Reserved for future extensions. Drivers and
|
||
|
|
applications must set the array to zero.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>&v4l2-ext-control; *</entry>
|
||
|
|
<entry><structfield>controls</structfield></entry>
|
||
|
|
<entry>Pointer to an array of
|
||
|
|
<structfield>count</structfield> v4l2_ext_control structures. Ignored
|
||
|
|
if <structfield>count</structfield> equals zero.</entry>
|
||
|
|
</row>
|
||
|
|
</tbody>
|
||
|
|
</tgroup>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<table pgwide="1" frame="none" id="ctrl-class">
|
||
|
|
<title>Control classes</title>
|
||
|
|
<tgroup cols="3">
|
||
|
|
&cs-def;
|
||
|
|
<tbody valign="top">
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_CTRL_CLASS_USER</constant></entry>
|
||
|
|
<entry>0x980000</entry>
|
||
|
|
<entry>The class containing user controls. These controls
|
||
|
|
are described in <xref linkend="control" />. All controls that can be set
|
||
|
|
using the &VIDIOC-S-CTRL; and &VIDIOC-G-CTRL; ioctl belong to this
|
||
|
|
class.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_CTRL_CLASS_MPEG</constant></entry>
|
||
|
|
<entry>0x990000</entry>
|
||
|
|
<entry>The class containing MPEG compression controls.
|
||
|
|
These controls are described in <xref
|
||
|
|
linkend="mpeg-controls" />.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_CTRL_CLASS_CAMERA</constant></entry>
|
||
|
|
<entry>0x9a0000</entry>
|
||
|
|
<entry>The class containing camera controls.
|
||
|
|
These controls are described in <xref
|
||
|
|
linkend="camera-controls" />.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_CTRL_CLASS_FM_TX</constant></entry>
|
||
|
|
<entry>0x9b0000</entry>
|
||
|
|
<entry>The class containing FM Transmitter (FM TX) controls.
|
||
|
|
These controls are described in <xref
|
||
|
|
linkend="fm-tx-controls" />.</entry>
|
||
|
|
</row>
|
||
|
|
</tbody>
|
||
|
|
</tgroup>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
<refsect1>
|
||
|
|
&return-value;
|
||
|
|
|
||
|
|
<variablelist>
|
||
|
|
<varlistentry>
|
||
|
|
<term><errorcode>EINVAL</errorcode></term>
|
||
|
|
<listitem>
|
||
|
|
<para>The &v4l2-ext-control; <structfield>id</structfield>
|
||
|
|
is invalid or the &v4l2-ext-controls;
|
||
|
|
<structfield>ctrl_class</structfield> is invalid. This error code is
|
||
|
|
also returned by the <constant>VIDIOC_S_EXT_CTRLS</constant> and
|
||
|
|
<constant>VIDIOC_TRY_EXT_CTRLS</constant> ioctls if two or more
|
||
|
|
control values are in conflict.</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><errorcode>ERANGE</errorcode></term>
|
||
|
|
<listitem>
|
||
|
|
<para>The &v4l2-ext-control; <structfield>value</structfield>
|
||
|
|
is out of bounds.</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><errorcode>EBUSY</errorcode></term>
|
||
|
|
<listitem>
|
||
|
|
<para>The control is temporarily not changeable, possibly
|
||
|
|
because another applications took over control of the device function
|
||
|
|
this control belongs to.</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><errorcode>ENOSPC</errorcode></term>
|
||
|
|
<listitem>
|
||
|
|
<para>The space reserved for the control's payload is insufficient.
|
||
|
|
The field <structfield>size</structfield> is set to a value that is enough
|
||
|
|
to store the payload and this error code is returned.</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
</variablelist>
|
||
|
|
</refsect1>
|
||
|
|
</refentry>
|
||
|
|
|
||
|
|
<!--
|
||
|
|
Local Variables:
|
||
|
|
mode: sgml
|
||
|
|
sgml-parent-document: "v4l2.sgml"
|
||
|
|
indent-tabs-mode: nil
|
||
|
|
End:
|
||
|
|
-->
|