Re: [PATCH 1/2] [media] V4L: Add camera pan/tilt speed controls

[Vincent Palatin]

On Sun, Aug 3, 2014 at 10:52 PM, Pawel Osciak <posciak@xxxxxxxxxxxx> wrote:
> This looks good to me in general (with one comment below). I don't think we
> can easily implement current V4L2 pan and tilt controls that are for
> movement by a specified amount in terms of UVC pan/tilt speed controls,
> which only let us set speed and direction...
>
> On Wed, Jul 9, 2014 at 8:49 AM, Vincent Palatin <vpalatin@xxxxxxxxxxxx>
> wrote:
>>
>> The V4L2_CID_PAN_SPEED and V4L2_CID_TILT_SPEED controls allow to move the
>> camera by setting its rotation speed around its axis.
>>
>> Signed-off-by: Vincent Palatin <vpalatin@xxxxxxxxxxxx>
>>
>> ---
>>  Documentation/DocBook/media/v4l/compat.xml   | 10 ++++++++++
>>  Documentation/DocBook/media/v4l/controls.xml | 21 +++++++++++++++++++++
>>  drivers/media/v4l2-core/v4l2-ctrls.c         |  2 ++
>>  include/uapi/linux/v4l2-controls.h           |  2 ++
>>  4 files changed, 35 insertions(+)
>>
>> diff --git a/Documentation/DocBook/media/v4l/compat.xml
>> b/Documentation/DocBook/media/v4l/compat.xml
>> index eee6f0f..21910e9 100644
>> --- a/Documentation/DocBook/media/v4l/compat.xml
>> +++ b/Documentation/DocBook/media/v4l/compat.xml
>> @@ -2545,6 +2545,16 @@ fields changed from _s32 to _u32.
>>        </orderedlist>
>>      </section>
>>
>> +    <section>
>> +      <title>V4L2 in Linux 3.17</title>
>> +      <orderedlist>
>> +       <listitem>
>> +         <para>Added <constant>V4L2_CID_PAN_SPEED</constant> and
>> + <constant>V4L2_CID_TILT_SPEED</constant> camera controls.</para>
>> +       </listitem>
>> +      </orderedlist>
>> +    </section>
>> +
>>      <section id="other">
>>        <title>Relation of V4L2 to other Linux multimedia APIs</title>
>>
>> diff --git a/Documentation/DocBook/media/v4l/controls.xml
>> b/Documentation/DocBook/media/v4l/controls.xml
>> index 47198ee..cdf97f0 100644
>> --- a/Documentation/DocBook/media/v4l/controls.xml
>> +++ b/Documentation/DocBook/media/v4l/controls.xml
>> @@ -3914,6 +3914,27 @@ by exposure, white balance or focus
>> controls.</entry>
>>           </row>
>>           <row><entry></entry></row>
>>
>> +         <row>
>> +           <entry
>> spanname="id"><constant>V4L2_CID_PAN_SPEED</constant>&nbsp;</entry>
>> +           <entry>integer</entry>
>> +         </row><row><entry spanname="descr">This control turns the
>> +camera horizontally at the specific speed. The unit is undefined. A
>> +positive value moves the camera to the right (clockwise when viewed
>> +from above), a negative value to the left. A value of zero does not
>> +cause or stop the motion.</entry>
>
>
> How do we stop/start?

As mentioned in the last sentence of the paragraph above, setting 0
stops the movement.
setting non-zero value starts it if needed.

>
>>
>> +         </row>
>> +         <row><entry></entry></row>
>> +
>> +         <row>
>> +           <entry
>> spanname="id"><constant>V4L2_CID_TILT_SPEED</constant>&nbsp;</entry>
>> +           <entry>integer</entry>
>> +         </row><row><entry spanname="descr">This control turns the
>> +camera vertically at the specified speed. The unit is undefined. A
>> +positive value moves the camera up, a negative value down. A value of
>> +zero does not cause or stop the motion.</entry>
>> +         </row>
>> +         <row><entry></entry></row>
>> +
>>         </tbody>
>>        </tgroup>
>>      </table>
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c
>> b/drivers/media/v4l2-core/v4l2-ctrls.c
>> index 55c6832..57ddaf4 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
>> @@ -787,6 +787,8 @@ const char *v4l2_ctrl_get_name(u32 id)
>>         case V4L2_CID_AUTO_FOCUS_STOP:          return "Auto Focus, Stop";
>>         case V4L2_CID_AUTO_FOCUS_STATUS:        return "Auto Focus,
>> Status";
>>         case V4L2_CID_AUTO_FOCUS_RANGE:         return "Auto Focus,
>> Range";
>> +       case V4L2_CID_PAN_SPEED:                return "Pan, Speed";
>> +       case V4L2_CID_TILT_SPEED:               return "Tilt, Speed";
>>
>>         /* FM Radio Modulator control */
>>         /* Keep the order of the 'case's the same as in videodev2.h! */
>> diff --git a/include/uapi/linux/v4l2-controls.h
>> b/include/uapi/linux/v4l2-controls.h
>> index 2ac5597..5576044 100644
>> --- a/include/uapi/linux/v4l2-controls.h
>> +++ b/include/uapi/linux/v4l2-controls.h
>> @@ -745,6 +745,8 @@ enum v4l2_auto_focus_range {
>>         V4L2_AUTO_FOCUS_RANGE_INFINITY          = 3,
>>  };
>>
>> +#define V4L2_CID_PAN_SPEED
>> (V4L2_CID_CAMERA_CLASS_BASE+32)
>> +#define V4L2_CID_TILT_SPEED
>> (V4L2_CID_CAMERA_CLASS_BASE+33)
>>
>>  /* FM Modulator class control IDs */
>>
>> --
>> 2.0.0.526.g5318336
>>
>
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