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SubjectRe: [PATCH 1/1] v4l: Add camera voice coil lens control class, current control
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Hi,

On 12.06.2016 23:41, Sakari Ailus wrote:
> From: Sakari Ailus <sakari.ailus@iki.fi>
>
> Add a V4L2 control class for voice coil lens driver devices. These are
> simple devices that are used to move a camera lens from its resting
> position.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
> Hi Pavel,
>
> I also don't think the FOCUS_ABSOLUTE controls is a really good one for
> the voice coil lens current. I expect more voice coil lens controls
> (linear vs. PWM mode, ringing compensation...) to be needed so I think
> it's worth a new class.
>

Right, I still think movement mode should be standard control :)

> Cc others, too...
>
> Kind regards,
> Sakari
>
> Documentation/DocBook/media/v4l/controls.xml | 55 +++++++++++++++++++++++++++-
> include/uapi/linux/v4l2-controls.h | 7 ++++
> 2 files changed, 61 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index e2e5484..aa7169c 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -5502,4 +5502,57 @@ receiving given frequency when that control is set. This is a read-only control.
> </tgroup>
> </table>
> </section>
> -</section>
> +
> + <section id="voice-coil-controls">
> + <title>Voice Coil Control Reference</title>
> +
> + <para>The Voice Coil class controls are used to control voice
> + coil lens devices. These are very simple devices that consist of
> + a voice coil, a spring and a lens. The current applied on a

There should be a magnet as well.

> + voice coil is used to move the lens away from the resting
> + position which typically is (close to) infinity.</para>
> +
> + <table pgwide="1" frame="none" id="voice-coil-control-id">
> + <title>Voice Coil Control IDs</title>
> +
> + <tgroup cols="4">
> + <colspec colname="c1" colwidth="1*" />
> + <colspec colname="c2" colwidth="6*" />
> + <colspec colname="c3" colwidth="2*" />
> + <colspec colname="c4" colwidth="6*" />
> + <spanspec namest="c1" nameend="c2" spanname="id" />
> + <spanspec namest="c2" nameend="c4" spanname="descr" />
> + <thead>
> + <row>
> + <entry spanname="id" align="left">ID</entry>
> + <entry align="left">Type</entry>
> + </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
> + </row>
> + </thead>
> + <tbody valign="top">
> + <row><entry></entry></row>
> + <row>
> + <entry spanname="id"><constant>V4L2_CID_VOICE_COIL_CLASS</constant>&nbsp;</entry>
> + <entry>class</entry>
> + </row><row><entry spanname="descr">The Voice Coil class
> +descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
> +description of this control class.</entry>
> + </row>
> + <row>
> + <entry spanname="id"><constant>V4L2_CID_VOICE_COIL_CURRENT</constant>&nbsp;</entry>
> + <entry>integer</entry>

I think this is no better than FOCUS_ABSOLUTE - nor "absolute" neither
"current" give any idea where is the lens (relatively to the rest
position) without userspace doing some calculations. What about
V4L2_CID_VOICE_COIL_POSITION, 0.000%-100.000% (pcm units)?

> + </row><row><entry spanname="descr">Current applied on a
> + voice coil. The more current is applied, the more is the
> + position of the lens moved from its resting position. Do
> + note that there may be a ringing effect; the lens will
> + oscillate after changing the current applied unless the
> + device implements ringing compensation.
> + </entry>
> + </row>
> + </tbody>
> + </tgroup>
> + </table>
> +
> + </section>
> +
> + </section>
> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> index b6a357a..c6b1261 100644
> --- a/include/uapi/linux/v4l2-controls.h
> +++ b/include/uapi/linux/v4l2-controls.h
> @@ -62,6 +62,7 @@
> #define V4L2_CTRL_CLASS_FM_RX 0x00a10000 /* FM Receiver controls */
> #define V4L2_CTRL_CLASS_RF_TUNER 0x00a20000 /* RF tuner controls */
> #define V4L2_CTRL_CLASS_DETECT 0x00a30000 /* Detection controls */
> +#define V4L2_CTRL_CLASS_VOICE_COIL 0x00a40000 /* Voice coil lens driver */
>
> /* User-class control IDs */
>
> @@ -974,4 +975,10 @@ enum v4l2_detect_md_mode {
> #define V4L2_CID_DETECT_MD_THRESHOLD_GRID (V4L2_CID_DETECT_CLASS_BASE + 3)
> #define V4L2_CID_DETECT_MD_REGION_GRID (V4L2_CID_DETECT_CLASS_BASE + 4)
>
> +/* Voice coil lens driver control IDs defined by V4L2 */
> +#define V4L2_CID_VOICE_COIL_CLASS_BASE (V4L2_CTRL_CLASS_VOICE_COIL | 0x900)
> +#define V4L2_CID_VOICE_COIL_CLASS (V4L2_CTRL_CLASS_VOICE_COIL | 1)
> +
> +#define V4L2_CID_VOICE_COIL_CURRENT (V4L2_CID_VOICE_COIL_CLASS_BASE + 1)
> +
> #endif
>

Ivo

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