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Subject[PATCH v2 10/10] Docbook: media: Document changes on struct v4l2_ext_controls
Date
Vidioc-g-ext-ctrls can now be used to get the default value of the
controls.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
Documentation/DocBook/media/v4l/v4l2.xml | 9 +++++++++
.../DocBook/media/v4l/vidioc-g-ext-ctrls.xml | 22 ++++++++++++++++++++++
2 files changed, 31 insertions(+)

diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index e98caa1c39bd..be52bd2fb335 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -153,6 +153,15 @@ structs, ioctls) must be noted in more detail in the history chapter
applications. -->

<revision>
+ <revnumber>4.4</revnumber>
+ <date>2015-08-20</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>
<revnumber>3.21</revnumber>
<date>2015-02-13</date>
<authorinitials>mcc</authorinitials>
diff --git a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
index 8f4eb395665d..3b7bf68a8250 100644
--- a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
@@ -216,7 +216,12 @@ Valid if <constant>V4L2_CTRL_FLAG_HAS_PAYLOAD</constant> is set for this control
<tgroup cols="3">
&cs-str;
<tbody valign="top">
+ <row>
+ <entry>union</entry>
+ <entry>(anonymous)</entry>
+ </row>
<row>
+ <entry></entry>
<entry>__u32</entry>
<entry><structfield>ctrl_class</structfield></entry>
<entry>The control class to which all controls belong, see
@@ -228,6 +233,23 @@ with a <structfield>count</structfield> of 0. If that succeeds, then the driver
supports this feature.</entry>
</row>
<row>
+ <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>
+</entry>
+ </row>
+ <row>
<entry>__u32</entry>
<entry><structfield>count</structfield></entry>
<entry>The number of controls in the controls array. May
--
2.5.0


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