V4L/DVB (12761): DocBook: add media API specs

The V4L and DVB API's are there for a long time. however, up to now,
no efforts were done to merge them to kernel DocBook.

This patch adds the current versions of the specs as an unique compendium.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 428 insertions, 0 deletions

diff --git a/Documentation/DocBook/v4l/vidioc-queryctrl.xml b/Documentation/DocBook/v4l/vidioc-queryctrl.xml
new file mode 100644
index 00000000000..4876ff1a1a0
--- /dev/null
+++ b/Documentation/DocBook/v4l/vidioc-queryctrl.xml
@@ -0,0 +1,428 @@
+<refentry id="vidioc-queryctrl">
+  <refmeta>
+    <refentrytitle>ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>VIDIOC_QUERYCTRL</refname>
+    <refname>VIDIOC_QUERYMENU</refname>
+    <refpurpose>Enumerate controls and menu control items</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_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_querymenu *<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_QUERYCTRL, VIDIOC_QUERYMENU</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>To query the attributes of a control applications set the
+<structfield>id</structfield> field of a &v4l2-queryctrl; and call the
+<constant>VIDIOC_QUERYCTRL</constant> ioctl with a pointer to this
+structure. The driver fills the rest of the structure or returns an
+&EINVAL; when the <structfield>id</structfield> is invalid.</para>
+
+    <para>It is possible to enumerate controls by calling
+<constant>VIDIOC_QUERYCTRL</constant> with successive
+<structfield>id</structfield> values starting from
+<constant>V4L2_CID_BASE</constant> up to and exclusive
+<constant>V4L2_CID_BASE_LASTP1</constant>. Drivers may return
+<errorcode>EINVAL</errorcode> if a control in this range is not
+supported. Further applications can enumerate private controls, which
+are not defined in this specification, by starting at
+<constant>V4L2_CID_PRIVATE_BASE</constant> and incrementing
+<structfield>id</structfield> until the driver returns
+<errorcode>EINVAL</errorcode>.</para>
+
+    <para>In both cases, when the driver sets the
+<constant>V4L2_CTRL_FLAG_DISABLED</constant> flag in the
+<structfield>flags</structfield> field this control is permanently
+disabled and should be ignored by the application.<footnote>
+	<para><constant>V4L2_CTRL_FLAG_DISABLED</constant> was
+intended for two purposes: Drivers can skip predefined controls not
+supported by the hardware (although returning EINVAL would do as
+well), or disable predefined and private controls after hardware
+detection without the trouble of reordering control arrays and indices
+(EINVAL cannot be used to skip private controls because it would
+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>
+
+    <para>Additional information is required for menu controls: the
+names of the menu items. To query them applications set the
+<structfield>id</structfield> and <structfield>index</structfield>
+fields of &v4l2-querymenu; and call the
+<constant>VIDIOC_QUERYMENU</constant> ioctl with a pointer to this
+structure. The driver fills the rest of the structure or returns an
+&EINVAL; when the <structfield>id</structfield> or
+<structfield>index</structfield> is invalid. Menu items are enumerated
+by calling <constant>VIDIOC_QUERYMENU</constant> with successive
+<structfield>index</structfield> values from &v4l2-queryctrl;
+<structfield>minimum</structfield> (0) to
+<structfield>maximum</structfield>, inclusive.</para>
+
+    <para>See also the examples in <xref linkend="control" />.</para>
+
+    <table pgwide="1" frame="none" id="v4l2-queryctrl">
+      <title>struct <structname>v4l2_queryctrl</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 V4L2_CTRL_FLAG_NEXT_CTRL the driver clears the flag and returns
+the first control with a higher ID. Drivers which do not support this
+flag yet always return an &EINVAL;.</entry>
+	  </row>
+	  <row>
+	    <entry>&v4l2-ctrl-type;</entry>
+	    <entry><structfield>type</structfield></entry>
+	    <entry>Type of control, see <xref
+		linkend="v4l2-ctrl-type" />.</entry>
+	  </row>
+	  <row>
+	    <entry>__u8</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>__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 (always 0) 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>
+	  </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_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>
+	  </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
+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><para>Note that although signed, the step value is supposed to
+be always positive.</para></entry>
+	  </row>
+	  <row>
+	    <entry>__s32</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>
+	  </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>reserved</structfield>[2]</entry>
+	    <entry>Reserved for future extensions. 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="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>id</structfield></entry>
+	    <entry>Identifies the control, set by the application
+from the respective &v4l2-queryctrl;
+<structfield>id</structfield>.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>index</structfield></entry>
+	    <entry>Index of the menu item, starting at zero, set by
+	    the application.</entry>
+	  </row>
+	  <row>
+	    <entry>__u8</entry>
+	    <entry><structfield>name</structfield>[32]</entry>
+	    <entry>Name of the menu item, a NUL-terminated ASCII
+string. This information is intended for the user.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>reserved</structfield></entry>
+	    <entry>Reserved for future extensions. Drivers must set
+the array to zero.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table pgwide="1" frame="none" id="v4l2-ctrl-type">
+      <title>enum v4l2_ctrl_type</title>
+      <tgroup cols="5" align="left">
+	<colspec colwidth="30*" />
+	<colspec colwidth="5*" align="center" />
+	<colspec colwidth="5*" align="center" />
+	<colspec colwidth="5*" align="center" />
+	<colspec colwidth="55*" />
+	<thead>
+	  <row>
+	    <entry>Type</entry>
+	    <entry><structfield>minimum</structfield></entry>
+	    <entry><structfield>step</structfield></entry>
+	    <entry><structfield>maximum</structfield></entry>
+	    <entry>Description</entry>
+	  </row>
+	</thead>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_INTEGER</constant></entry>
+	    <entry>any</entry>
+	    <entry>any</entry>
+	    <entry>any</entry>
+	    <entry>An integer-valued control ranging from minimum to
+maximum inclusive. The step value indicates the increment between
+values which are actually different on the hardware.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_BOOLEAN</constant></entry>
+	    <entry>0</entry>
+	    <entry>1</entry>
+	    <entry>1</entry>
+	    <entry>A boolean-valued control. Zero corresponds to
+"disabled", and one means "enabled".</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_MENU</constant></entry>
+	    <entry>0</entry>
+	    <entry>1</entry>
+	    <entry>N-1</entry>
+	    <entry>The control has a menu of N choices. The names of
+the menu items can be enumerated with the
+<constant>VIDIOC_QUERYMENU</constant> ioctl.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_BUTTON</constant></entry>
+	    <entry>0</entry>
+	    <entry>0</entry>
+	    <entry>0</entry>
+	    <entry>A control which performs an action when set.
+Drivers must ignore the value passed with
+<constant>VIDIOC_S_CTRL</constant> and return an &EINVAL; on a
+<constant>VIDIOC_G_CTRL</constant> attempt.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_INTEGER64</constant></entry>
+	    <entry>n/a</entry>
+	    <entry>n/a</entry>
+	    <entry>n/a</entry>
+	    <entry>A 64-bit integer valued control. Minimum, maximum
+and step size cannot be queried.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_STRING</constant></entry>
+	    <entry>&ge; 0</entry>
+	    <entry>&ge; 1</entry>
+	    <entry>&ge; 0</entry>
+	    <entry>The minimum and maximum string lengths. The step size
+means that the string must be (minimum + N * step) characters long for
+N &ge; 0. These lengths do not include the terminating zero, so in order to
+pass a string of length 8 to &VIDIOC-S-EXT-CTRLS; you need to set the
+<structfield>size</structfield> field of &v4l2-ext-control; to 9. For &VIDIOC-G-EXT-CTRLS; you can
+set the <structfield>size</structfield> field to <structfield>maximum</structfield> + 1.
+Which character encoding is used will depend on the string control itself and
+should be part of the control documentation.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant></entry>
+	    <entry>n/a</entry>
+	    <entry>n/a</entry>
+	    <entry>n/a</entry>
+	    <entry>This is not a control. When
+<constant>VIDIOC_QUERYCTRL</constant> is called with a control ID
+equal to a control class code (see <xref linkend="ctrl-class" />), the
+ioctl returns the name of the control class and this control type.
+Older drivers which do not support this feature return an
+&EINVAL;.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table pgwide="1" frame="none" id="control-flags">
+      <title>Control Flags</title>
+      <tgroup cols="3">
+	&cs-def;
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_DISABLED</constant></entry>
+	    <entry>0x0001</entry>
+	    <entry>This control is permanently disabled and should be
+ignored by the application. Any attempt to change the control will
+result in an &EINVAL;.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_GRABBED</constant></entry>
+	    <entry>0x0002</entry>
+	    <entry>This control is temporarily unchangeable, for
+example because another application took over control of the
+respective resource. Such controls may be displayed specially in a
+user interface. Attempts to change the control may result in an
+&EBUSY;.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_READ_ONLY</constant></entry>
+	    <entry>0x0004</entry>
+	    <entry>This control is permanently readable only. Any
+attempt to change the control will result in an &EINVAL;.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_UPDATE</constant></entry>
+	    <entry>0x0008</entry>
+	    <entry>A hint that changing this control may affect the
+value of other controls within the same control class. Applications
+should update their user interface accordingly.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_INACTIVE</constant></entry>
+	    <entry>0x0010</entry>
+	    <entry>This control is not applicable to the current
+configuration and should be displayed accordingly in a user interface.
+For example the flag may be set on a MPEG audio level 2 bitrate
+control when MPEG audio encoding level 1 was selected with another
+control.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_SLIDER</constant></entry>
+	    <entry>0x0020</entry>
+	    <entry>A hint that this control is best represented as a
+slider-like element in a user interface.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_FLAG_WRITE_ONLY</constant></entry>
+	    <entry>0x0040</entry>
+	    <entry>This control is permanently writable only. Any
+attempt to read the control will result in an &EACCES; error code. This
+flag is typically present for relative controls or action controls where
+writing a value will cause the device to carry out a given action
+(&eg; motor control) but no meaningful value can be returned.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The &v4l2-queryctrl; <structfield>id</structfield>
+is invalid. The &v4l2-querymenu; <structfield>id</structfield> or
+<structfield>index</structfield> is invalid.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EACCES</errorcode></term>
+	<listitem>
+	  <para>An attempt was made to read a write-only control.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->