mirror of https://gitee.com/openkylin/linux.git
[media] DocBook media: document VIDIOC_QUERY_EXT_CTRL
Document the new VIDIOC_QUERY_EXT_CTRL ioctl. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Hans Verkuil
Mauro Carvalho Chehab
parent
40265bbe42
commit
715bfb3e1f
|
|
@ -1,11 +1,12 @@
|
|||
<refentry id="vidioc-queryctrl">
|
||||
<refmeta>
|
||||
<refentrytitle>ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU</refentrytitle>
|
||||
<refentrytitle>ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERY_EXT_CTRL, VIDIOC_QUERYMENU</refentrytitle>
|
||||
&manvol;
|
||||
</refmeta>
|
||||
|
||||
<refnamediv>
|
||||
<refname>VIDIOC_QUERYCTRL</refname>
|
||||
<refname>VIDIOC_QUERY_EXT_CTRL</refname>
|
||||
<refname>VIDIOC_QUERYMENU</refname>
|
||||
<refpurpose>Enumerate controls and menu control items</refpurpose>
|
||||
</refnamediv>
|
||||
|
|
@ -19,6 +20,14 @@
|
|||
<paramdef>struct v4l2_queryctrl *<parameter>argp</parameter></paramdef>
|
||||
</funcprototype>
|
||||
</funcsynopsis>
|
||||
<funcsynopsis>
|
||||
<funcprototype>
|
||||
<funcdef>int <function>ioctl</function></funcdef>
|
||||
<paramdef>int <parameter>fd</parameter></paramdef>
|
||||
<paramdef>int <parameter>request</parameter></paramdef>
|
||||
<paramdef>struct v4l2_query_ext_ctrl *<parameter>argp</parameter></paramdef>
|
||||
</funcprototype>
|
||||
</funcsynopsis>
|
||||
<funcsynopsis>
|
||||
<funcprototype>
|
||||
<funcdef>int <function>ioctl</function></funcdef>
|
||||
|
|
@ -42,7 +51,7 @@
|
|||
<varlistentry>
|
||||
<term><parameter>request</parameter></term>
|
||||
<listitem>
|
||||
<para>VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU</para>
|
||||
<para>VIDIOC_QUERYCTRL, VIDIOC_QUERY_EXT_CTRL, VIDIOC_QUERYMENU</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
|
|
@ -89,9 +98,23 @@ prematurely end the enumeration).</para></footnote></para>
|
|||
|
||||
<para>When the application ORs <structfield>id</structfield> with
|
||||
<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> the driver returns the
|
||||
next supported control, or <errorcode>EINVAL</errorcode> if there is
|
||||
none. Drivers which do not support this flag yet always return
|
||||
<errorcode>EINVAL</errorcode>.</para>
|
||||
next supported non-compound control, or <errorcode>EINVAL</errorcode>
|
||||
if there is none. In addition, the <constant>V4L2_CTRL_FLAG_NEXT_COMPOUND</constant>
|
||||
flag can be specified to enumerate all compound controls (i.e. controls
|
||||
with type ≥ <constant>V4L2_CTRL_COMPOUND_TYPES</constant>). Specify both
|
||||
<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> and
|
||||
<constant>V4L2_CTRL_FLAG_NEXT_COMPOUND</constant> in order to enumerate
|
||||
all controls, compound or not. Drivers which do not support these flags yet
|
||||
always return <errorcode>EINVAL</errorcode>.</para>
|
||||
|
||||
<para>The <constant>VIDIOC_QUERY_EXT_CTRL</constant> ioctl was
|
||||
introduced in order to better support controls that can use compound
|
||||
types, and to expose additional control information that cannot be
|
||||
returned in &v4l2-queryctrl; since that structure is full.</para>
|
||||
|
||||
<para><constant>VIDIOC_QUERY_EXT_CTRL</constant> is used in the
|
||||
same way as <constant>VIDIOC_QUERYCTRL</constant>, except that the
|
||||
<structfield>reserved</structfield> array must be zeroed as well.</para>
|
||||
|
||||
<para>Additional information is required for menu controls: the
|
||||
names of the menu items. To query them applications set the
|
||||
|
|
@ -142,38 +165,23 @@ string. This information is intended for the user.</entry>
|
|||
<entry>__s32</entry>
|
||||
<entry><structfield>minimum</structfield></entry>
|
||||
<entry>Minimum value, inclusive. This field gives a lower
|
||||
bound for <constant>V4L2_CTRL_TYPE_INTEGER</constant> controls and the
|
||||
lowest valid index for <constant>V4L2_CTRL_TYPE_MENU</constant> controls.
|
||||
For <constant>V4L2_CTRL_TYPE_STRING</constant> controls the minimum value
|
||||
gives the minimum length of the string. This length <emphasis>does not include the terminating
|
||||
zero</emphasis>. It may not be valid for any other type of control, including
|
||||
<constant>V4L2_CTRL_TYPE_INTEGER64</constant> controls. Note that this is a
|
||||
signed value.</entry>
|
||||
bound for the control. See &v4l2-ctrl-type; how the minimum value is to
|
||||
be used for each possible control type. Note that this a signed 32-bit value.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__s32</entry>
|
||||
<entry><structfield>maximum</structfield></entry>
|
||||
<entry>Maximum value, inclusive. This field gives an upper
|
||||
bound for <constant>V4L2_CTRL_TYPE_INTEGER</constant> controls and the
|
||||
highest valid index for <constant>V4L2_CTRL_TYPE_MENU</constant>
|
||||
controls. For <constant>V4L2_CTRL_TYPE_BITMASK</constant> controls it is the
|
||||
set of usable bits.
|
||||
For <constant>V4L2_CTRL_TYPE_STRING</constant> controls the maximum value
|
||||
gives the maximum length of the string. This length <emphasis>does not include the terminating
|
||||
zero</emphasis>. It may not be valid for any other type of control, including
|
||||
<constant>V4L2_CTRL_TYPE_INTEGER64</constant> controls. Note that this is a
|
||||
signed value.</entry>
|
||||
bound for the control. See &v4l2-ctrl-type; how the maximum value is to
|
||||
be used for each possible control type. Note that this a signed 32-bit value.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__s32</entry>
|
||||
<entry><structfield>step</structfield></entry>
|
||||
<entry><para>This field gives a step size for
|
||||
<constant>V4L2_CTRL_TYPE_INTEGER</constant> controls. For
|
||||
<constant>V4L2_CTRL_TYPE_STRING</constant> controls this field refers to
|
||||
the string length that has to be a multiple of this step size.
|
||||
It may not be valid for any other type of control, including
|
||||
<constant>V4L2_CTRL_TYPE_INTEGER64</constant>
|
||||
controls.</para><para>Generally drivers should not scale hardware
|
||||
<entry><para>This field gives a step size for the control.
|
||||
See &v4l2-ctrl-type; how the step value is to be used for each possible
|
||||
control type. Note that this an unsigned 32-bit value.
|
||||
</para><para>Generally drivers should not scale hardware
|
||||
control values. It may be necessary for example when the
|
||||
<structfield>name</structfield> or <structfield>id</structfield> imply
|
||||
a particular unit and the hardware actually accepts only multiples of
|
||||
|
|
@ -192,10 +200,11 @@ be always positive.</para></entry>
|
|||
<entry><structfield>default_value</structfield></entry>
|
||||
<entry>The default value of a
|
||||
<constant>V4L2_CTRL_TYPE_INTEGER</constant>,
|
||||
<constant>_BOOLEAN</constant> or <constant>_MENU</constant> control.
|
||||
Not valid for other types of controls. Drivers reset controls only
|
||||
when the driver is loaded, not later, in particular not when the
|
||||
func-open; is called.</entry>
|
||||
<constant>_BOOLEAN</constant>, <constant>_BITMASK</constant>,
|
||||
<constant>_MENU</constant> or <constant>_INTEGER_MENU</constant> control.
|
||||
Not valid for other types of controls.
|
||||
Note that drivers reset controls to their default value only when the
|
||||
driver is first loaded, never afterwards.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
|
|
@ -213,6 +222,125 @@ the array to zero.</entry>
|
|||
</tgroup>
|
||||
</table>
|
||||
|
||||
<table pgwide="1" frame="none" id="v4l2-query-ext-ctrl">
|
||||
<title>struct <structname>v4l2_query_ext_ctrl</structname></title>
|
||||
<tgroup cols="3">
|
||||
&cs-str;
|
||||
<tbody valign="top">
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>id</structfield></entry>
|
||||
<entry>Identifies the control, set by the application. See
|
||||
<xref linkend="control-id" /> for predefined IDs. When the ID is ORed
|
||||
with <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> the driver clears the
|
||||
flag and returns the first non-compound control with a higher ID. When the
|
||||
ID is ORed with <constant>V4L2_CTRL_FLAG_NEXT_COMPOUND</constant> the driver
|
||||
clears the flag and returns the first compound control with a higher ID.
|
||||
Set both to get the first control (compound or not) with a higher ID.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>type</structfield></entry>
|
||||
<entry>Type of control, see <xref
|
||||
linkend="v4l2-ctrl-type" />.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>char</entry>
|
||||
<entry><structfield>name</structfield>[32]</entry>
|
||||
<entry>Name of the control, a NUL-terminated ASCII
|
||||
string. This information is intended for the user.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__s64</entry>
|
||||
<entry><structfield>minimum</structfield></entry>
|
||||
<entry>Minimum value, inclusive. This field gives a lower
|
||||
bound for the control. See &v4l2-ctrl-type; how the minimum value is to
|
||||
be used for each possible control type. Note that this a signed 64-bit value.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__s64</entry>
|
||||
<entry><structfield>maximum</structfield></entry>
|
||||
<entry>Maximum value, inclusive. This field gives an upper
|
||||
bound for the control. See &v4l2-ctrl-type; how the maximum value is to
|
||||
be used for each possible control type. Note that this a signed 64-bit value.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u64</entry>
|
||||
<entry><structfield>step</structfield></entry>
|
||||
<entry><para>This field gives a step size for the control.
|
||||
See &v4l2-ctrl-type; how the step value is to be used for each possible
|
||||
control type. Note that this an unsigned 64-bit value.
|
||||
</para><para>Generally drivers should not scale hardware
|
||||
control values. It may be necessary for example when the
|
||||
<structfield>name</structfield> or <structfield>id</structfield> imply
|
||||
a particular unit and the hardware actually accepts only multiples of
|
||||
said unit. If so, drivers must take care values are properly rounded
|
||||
when scaling, such that errors will not accumulate on repeated
|
||||
read-write cycles.</para><para>This field gives the smallest change of
|
||||
an integer control actually affecting hardware. Often the information
|
||||
is needed when the user can change controls by keyboard or GUI
|
||||
buttons, rather than a slider. When for example a hardware register
|
||||
accepts values 0-511 and the driver reports 0-65535, step should be
|
||||
128.</para></entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__s64</entry>
|
||||
<entry><structfield>default_value</structfield></entry>
|
||||
<entry>The default value of a
|
||||
<constant>V4L2_CTRL_TYPE_INTEGER</constant>, <constant>_INTEGER64</constant>,
|
||||
<constant>_BOOLEAN</constant>, <constant>_BITMASK</constant>,
|
||||
<constant>_MENU</constant> or <constant>_INTEGER_MENU</constant> control.
|
||||
Not valid for other types of controls.
|
||||
Note that drivers reset controls to their default value only when the
|
||||
driver is first loaded, never afterwards.
|
||||
</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>flags</structfield></entry>
|
||||
<entry>Control flags, see <xref
|
||||
linkend="control-flags" />.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>elem_size</structfield></entry>
|
||||
<entry>The size in bytes of a single element of the array.
|
||||
Given a char pointer <constant>p</constant> to a 3-dimensional array you can find the
|
||||
position of cell <constant>(z, y, x)</constant> as follows:
|
||||
<constant>p + ((z * dims[1] + y) * dims[0] + x) * elem_size</constant>. <structfield>elem_size</structfield>
|
||||
is always valid, also when the control isn't an array. For string controls
|
||||
<structfield>elem_size</structfield> is equal to <structfield>maximum + 1</structfield>.
|
||||
</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>elems</structfield></entry>
|
||||
<entry>The number of elements in the N-dimensional array. If this control
|
||||
is not an array, then <structfield>elems</structfield> is 1. The <structfield>elems</structfield>
|
||||
field can never be 0.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>nr_of_dims</structfield></entry>
|
||||
<entry>The number of dimension in the N-dimensional array. If this control
|
||||
is not an array, then this field is 0.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>dims[V4L2_CTRL_MAX_DIMS]</structfield></entry>
|
||||
<entry>The size of each dimension. The first <structfield>nr_of_dims</structfield>
|
||||
elements of this array must be non-zero, all remaining elements must be zero.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>__u32</entry>
|
||||
<entry><structfield>reserved</structfield>[32]</entry>
|
||||
<entry>Reserved for future extensions. Applications and drivers
|
||||
must set the array to zero.</entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</table>
|
||||
|
||||
<table pgwide="1" frame="none" id="v4l2-querymenu">
|
||||
<title>struct <structname>v4l2_querymenu</structname></title>
|
||||
<tgroup cols="4">
|
||||
|
|
@ -347,11 +475,14 @@ Drivers must ignore the value passed with
|
|||
</row>
|
||||
<row>
|
||||
<entry><constant>V4L2_CTRL_TYPE_INTEGER64</constant></entry>
|
||||
<entry>n/a</entry>
|
||||
<entry>n/a</entry>
|
||||
<entry>n/a</entry>
|
||||
<entry>any</entry>
|
||||
<entry>any</entry>
|
||||
<entry>any</entry>
|
||||
<entry>A 64-bit integer valued control. Minimum, maximum
|
||||
and step size cannot be queried.</entry>
|
||||
and step size cannot be queried using <constant>VIDIOC_QUERYCTRL</constant>.
|
||||
Only <constant>VIDIOC_QUERY_EXT_CTRL</constant> can retrieve the 64-bit
|
||||
min/max/step values, they should be interpreted as n/a when using
|
||||
<constant>VIDIOC_QUERYCTRL</constant>.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry><constant>V4L2_CTRL_TYPE_STRING</constant></entry>
|
||||
|
|
@ -450,6 +581,14 @@ is in auto-gain mode. In such a case the hardware calculates the gain value base
|
|||
the lighting conditions which can change over time. Note that setting a new value for
|
||||
a volatile control will have no effect. The new value will just be ignored.</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry><constant>V4L2_CTRL_FLAG_HAS_PAYLOAD</constant></entry>
|
||||
<entry>0x0100</entry>
|
||||
<entry>This control has a pointer type, so its value has to be accessed
|
||||
using one of the pointer fields of &v4l2-ext-control;. This flag is set for controls
|
||||
that are an array, string, or have a compound type. In all cases you have to set a
|
||||
pointer to memory containing the payload of the control.</entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</table>
|
||||
|
|
|
|||
Loading…
Reference in New Issue