Re: [PATCH/RFC][DRAFT] V4L: Add camera auto focus controls

[Sylwester Nawrocki <snjw23@gmail.com>]

Hi,

On 01/16/2012 10:33 PM, Sylwester Nawrocki wrote:
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 012a296..0808b12 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -1662,6 +1662,34 @@ enum  v4l2_exposure_auto_type {
>   #define V4L2_CID_IRIS_ABSOLUTE			(V4L2_CID_CAMERA_CLASS_BASE+17)
>   #define V4L2_CID_IRIS_RELATIVE			(V4L2_CID_CAMERA_CLASS_BASE+18)
>
> +#define V4L2_CID_AUTO_FOCUS_START		(V4L2_CID_CAMERA_CLASS_BASE+19)
> +#define V4L2_CID_AUTO_FOCUS_STOP		(V4L2_CID_CAMERA_CLASS_BASE+20)
> +#define V4L2_CID_AUTO_FOCUS_STATUS		(V4L2_CID_CAMERA_CLASS_BASE+21)
> +enum v4l2_auto_focus_status {
> +	V4L2_AUTO_FOCUS_STATUS_IDLE		= 0,
> +	V4L2_AUTO_FOCUS_STATUS_BUSY		= 1,
> +	V4L2_AUTO_FOCUS_STATUS_SUCCESS		= 2,
> +	V4L2_AUTO_FOCUS_STATUS_FAIL		= 3,
> +};
> +
> +#define V4L2_CID_AUTO_FOCUS_DISTANCE		(V4L2_CID_CAMERA_CLASS_BASE+22)
> +enum v4l2_auto_focus_distance {
> +	V4L2_AUTO_FOCUS_DISTANCE_NORMAL		= 0,
> +	V4L2_AUTO_FOCUS_DISTANCE_MACRO		= 1,
> +	V4L2_AUTO_FOCUS_DISTANCE_INFINITY	= 2,
> +};
> +
> +#define V4L2_CID_AUTO_FOCUS_SELECTION		(V4L2_CID_CAMERA_CLASS_BASE+23)
> +enum v4l2_auto_focus_selection {
> +	V4L2_AUTO_FOCUS_SELECTION_NORMAL	= 0,
> +	V4L2_AUTO_FOCUS_SELECTION_SPOT		= 1,
> +	V4L2_AUTO_FOCUS_SELECTION_RECTANGLE	= 2,
> +};

I'd like to ask your advice, I've found those two above controls 
rather painful in use. After changing V4L2_CID_AUTO_FOCUS_SELECTION to

#define V4L2_CID_AUTO_FOCUS_AREA		(V4L2_CID_CAMERA_CLASS_BASE+23)
enum v4l2_auto_focus_selection {
	V4L2_AUTO_FOCUS_SELECTION_ALL		= 0,
	V4L2_AUTO_FOCUS_SELECTION_SPOT		= 1,
	V4L2_AUTO_FOCUS_SELECTION_RECTANGLE	= 2,
};

I tried use them with the M-5MOLS sensor driver where there is only 
one register for setting following automatic focus modes:

NORMAL AUTO (single-shot),
MACRO,
INFINITY,
SPOT,
FACE_DETECTION

The issue is that when V4L2_CID_AUTO_FOCUS_AREA is set to for example
V4L2_AUTO_FOCUS_SELECTION_SPOT, none of the menu entries of
V4L2_CID_AUTO_FOCUS_DISTANCE is valid.

So it would really be better to use single control for automatic focus
mode. A private control could handle that. But there will be more than
one sensor driver needing such a control, so I thought about an
additional header, e.g. samsung_camera.h in include/linux/ that would 
define reguired control IDs and menus in the camera class private id 
range.

What do you think about it ?


> +#define V4L2_CID_AUTO_FOCUS_X_POSITION		(V4L2_CID_CAMERA_CLASS_BASE+24)
> +#define V4L2_CID_AUTO_FOCUS_Y_POSITION		(V4L2_CID_CAMERA_CLASS_BASE+25)
...

--

Regards,
Sylwester