[PATCH v2 6/6] Docbook: media: Document changes on struct v4l2_ext_controls

From: Ricardo Ribalda Delgado
Date: Thu Oct 29 2015 - 06:10:59 EST

Vidioc-g-ext-ctrls can now be used to get the default value of the

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
Documentation/DocBook/media/v4l/v4l2.xml | 10 ++++++++++
.../DocBook/media/v4l/vidioc-g-ext-ctrls.xml | 22 ++++++++++++++++++++++
2 files changed, 32 insertions(+)

diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index 7e61643358de..42e626d6c936 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -152,6 +152,16 @@ structs, ioctls) must be noted in more detail in the history chapter
(compat.xml), along with the possible impact on existing drivers and
applications. -->
+ <revnumber>4.5</revnumber>
+ <date>2015-10-29</date>
+ <authorinitials>rr</authorinitials>
+ <revremark>Extend vidioc-g-ext-ctrls;. Replace ctrl_class with a new
+union with ctrl_class and which. Which is used to select the current value of
+the control or the default value.
+ </revremark>
+ </revision>
+ <revision>
diff --git a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
index 47f9fee91442..eb82f7e7d06b 100644
--- a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
@@ -223,7 +223,12 @@ Valid if <constant>V4L2_CTRL_FLAG_HAS_PAYLOAD</constant> is set for this control
<tgroup cols="3">
<tbody valign="top">
+ <row>
+ <entry>union</entry>
+ <entry>(anonymous)</entry>
+ </row>
+ <entry></entry>
<entry>The control class to which all controls belong, see
@@ -235,6 +240,23 @@ with a <structfield>count</structfield> of 0. If that succeeds, then the driver
supports this feature.</entry>
+ <entry></entry>
+ <entry>__u32</entry>
+ <entry><structfield>which</structfield></entry>
+ <entry><para>Which value of the control to get/set/try. <constant>V4L2_CTRL_WHICH_CUR_VAL</constant>
+will return the current value of the control and <constant>V4L2_CTRL_WHICH_DEF_VAL</constant> will
+return the default value of the control. Please note that you can only get the default value of the
+control, you cannot set or try it.</para>
+<para>For backwards compatibility you can also use a control class here (see
+<xref linkend="ctrl-class" />). In that case all controls have to belong to that
+control class. This usage is deprecated, instead just use <constant>V4L2_CTRL_WHICH_CUR_VAL</constant>.
+There are some very old drivers that do not yet support <constant>V4L2_CTRL_WHICH_CUR_VAL</constant>
+and that require a control class here. You can test for such drivers by setting ctrl_class to
+<constant>V4L2_CTRL_WHICH_CUR_VAL</constant> and calling VIDIOC_TRY_EXT_CTRLS with a count of 0.
+If that fails, then the driver does not support <constant>V4L2_CTRL_WHICH_CUR_VAL</constant>.</para>
+ </row>
+ <row>
<entry>The number of controls in the controls array. May

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