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

Vincent Palatin
2014-08-06T15:10:44Z

On Sun, Aug 3, 2014 at 10:52 PM, Pawel Osciak <posciak@chromium.org> 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@chromium.org>
> 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@chromium.org>
>>
>> ---
>> 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.
>>
>>
>>
>> +
>> + V4L2 in Linux 3.17
>> +
>> +
>> + Added <constant>V4L2_CID_PAN_SPEED</constant> and
>> + <constant>V4L2_CID_TILT_SPEED</constant> camera controls.
>> +
>> +
>> +
>> +
>>
>> Relation of V4L2 to other Linux multimedia APIs
>>
>> 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>
>> +
>>
>> </tgroup>
>>
>> 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
>>
>