On 08/21/2015 11:29 AM, Ricardo Ribalda Delgado wrote:
> Vidioc-g-ext-ctrls can now be used to get the default value of the
> controls.
>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.riba...@gmail.com>
> ---
> Documentation/DocBook/media/v4l/v4l2.xml | 9 +++++++++
> Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml | 14 ++++++++++++++
> 2 files changed, 23 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 c5bdbfcc42b3..224fa2bd1481 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 +233,15 @@ with a <structfield>count</structfield> of 0. If that
> succeeds, then the driver
> supports this feature.</entry>
All I would say here is that ctrl_class is an alias for 'which', kept for
backwards compatibility.
Applications should use 'which' instead.
> </row>
> <row>
> + <entry></entry>
> + <entry>__u32</entry>
> + <entry><structfield>which</structfield></entry>
> + <entry> Which control are get/set/tried.
> <constant>V4L2_CTRL_WHICH_CUR_VAL</constant>
I'd say: "Which value of the control to get/set/try."
> +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 the default value
> of the control cannot
> +be set or tried, only get.</entry>
I'd rephrase that:
"Please note that you can only get the default value of the control, you cannot
set or try it."
Add this:
"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>."
I think the only driver that still doesn't support this is saa7164. I really
need
to convert it to the control framework.
Regards,
Hans
> + </row>
> + <row>
> <entry>__u32</entry>
> <entry><structfield>count</structfield></entry>
> <entry>The number of controls in the controls array. May
>
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