Hi Ming,

Thanks for the patchset.

(Dropped a lot of folks from cc --- I doubt Alan Cox or Greg
Kroah-Hartman have immediate interest towards this.)

On Fri, Dec 02, 2011 at 11:02:50PM +0800, Ming Lei wrote:
> This patch introduces two new IOCTLs and related data
> structure defination which will be used by the coming
> face detection video device.
> 
> The two IOCTLs and related data structure are used by
> user space application to retrieve the results of face
> detection. They can be called after one v4l2_buffer
> has been ioctl(VIDIOC_DQBUF) and before it will be
> ioctl(VIDIOC_QBUF).
> 
> The utility fdif[1] is useing the two IOCTLs to find
> faces deteced in raw images or video streams.
> 
> [1],http://kernel.ubuntu.com/git?p=ming/fdif.git;a=shortlog;h=refs/heads/v4l2-fdif
> 
> Signed-off-by: Ming Lei <ming....@canonical.com>
> ---
>  drivers/media/video/v4l2-ioctl.c |   38 ++++++++++++++++++++
>  include/linux/videodev2.h        |   70 
> ++++++++++++++++++++++++++++++++++++++
>  include/media/v4l2-ioctl.h       |    6 +++
>  3 files changed, 114 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/media/video/v4l2-ioctl.c 
> b/drivers/media/video/v4l2-ioctl.c
> index e1da8fc..fc6266f 100644
> --- a/drivers/media/video/v4l2-ioctl.c
> +++ b/drivers/media/video/v4l2-ioctl.c
> @@ -2140,6 +2140,30 @@ static long __video_do_ioctl(struct file *file,
>               dbgarg(cmd, "index=%d", b->index);
>               break;
>       }
> +     case VIDIOC_G_FD_RESULT:
> +     {
> +             struct v4l2_fd_result *fr = arg;
> +
> +             if (!ops->vidioc_g_fd_result)
> +                     break;
> +
> +             ret = ops->vidioc_g_fd_result(file, fh, fr);
> +
> +             dbgarg(cmd, "index=%d", fr->buf_index);
> +             break;
> +     }
> +     case VIDIOC_G_FD_COUNT:
> +     {
> +             struct v4l2_fd_count *fc = arg;
> +
> +             if (!ops->vidioc_g_fd_count)
> +                     break;
> +
> +             ret = ops->vidioc_g_fd_count(file, fh, fc);
> +
> +             dbgarg(cmd, "index=%d", fc->buf_index);
> +             break;
> +     }

The patch description tells these ioctls may be called between... what? I'd
think such information could be better provided as events.

How is face detection enabled or disabled?

Could you detect other objects than faces?

Would events be large enough to deliver you the necessary data? We could
also consider delivering the information as a data structure on a separate
plane.

>       default:
>               if (!ops->vidioc_default)
>                       break;
> @@ -2234,6 +2258,20 @@ static int check_array_args(unsigned int cmd, void 
> *parg, size_t *array_size,
>               }
>               break;
>       }
> +
> +     case VIDIOC_G_FD_RESULT: {
> +             struct v4l2_fd_result *fr = parg;
> +
> +             if (fr->face_cnt != 0) {
> +                     *user_ptr = (void __user *)fr->fd;
> +                     *kernel_ptr = (void *)&fr->fd;
> +                     *array_size = sizeof(struct v4l2_fd_detection)
> +                                 * fr->face_cnt;
> +                     ret = 1;
> +             }
> +             break;
> +
> +     }
>       }
>  
>       return ret;
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 4b752d5..073eb4d 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -2160,6 +2160,74 @@ struct v4l2_create_buffers {
>       __u32                   reserved[8];
>  };
>  
> +/**
> + * struct v4l2_obj_detection
> + * @buf_index:       entry, index of v4l2_buffer for face detection
> + * @centerx: return, position in x direction of detected object
> + * @centery: return, position in y direction of detected object
> + * @angle:   return, angle of detected object
> + *           0 deg ~ 359 deg, vertical is 0 deg, clockwise
> + * @sizex:   return, size in x direction of detected object
> + * @sizey:   return, size in y direction of detected object
> + * @confidence:      return, confidence level of detection result
> + *           0: the heighest level, 9: the lowest level
> + * @reserved:        future extensions
> + */
> +struct v4l2_obj_detection {
> +     __u16           centerx;
> +     __u16           centery;
> +     __u16           angle;
> +     __u16           sizex;
> +     __u16           sizey;
> +     __u16           confidence;
> +     __u32           reserved[4];
> +};
> +
> +#define V4L2_FD_HAS_LEFT_EYE 0x1
> +#define V4L2_FD_HAS_RIGHT_EYE        0x2
> +#define V4L2_FD_HAS_MOUTH    0x4
> +#define V4L2_FD_HAS_FACE     0x8
> +
> +/**
> + * struct v4l2_fd_detection - VIDIOC_G_FD_RESULT argument
> + * @flag:    return, describe which objects are detected
> + * @left_eye:        return, left_eye position if detected
> + * @right_eye:       return, right_eye position if detected
> + * @mouth_eye:       return, mouth_eye position if detected
> + * @face:    return, face position if detected
> + */
> +struct v4l2_fd_detection {
> +     __u32   flag;
> +     struct v4l2_obj_detection       left_eye;
> +     struct v4l2_obj_detection       right_eye;
> +     struct v4l2_obj_detection       mouth;
> +     struct v4l2_obj_detection       face;
> +};
> +
> +/**
> + * struct v4l2_fd_result - VIDIOC_G_FD_RESULT argument
> + * @buf_index:       entry, index of v4l2_buffer for face detection
> + * @face_cnt:        return, how many faces detected from the @buf_index
> + * @fd:              return, result of faces' detection
> + */
> +struct v4l2_fd_result {
> +     __u32   buf_index;
> +     __u32   face_cnt;
> +     __u32   reserved[6];
> +     struct v4l2_fd_detection *fd;

Aligning structure sizes to a power of two is considered to be a good
practice.

> +};
> +
> +/**
> + * struct v4l2_fd_count - VIDIOC_G_FD_COUNT argument
> + * @buf_index:       entry, index of v4l2_buffer for face detection
> + * @face_cnt:        return, how many faces detected from the @buf_index
> + */
> +struct v4l2_fd_count {
> +     __u32   buf_index;
> +     __u32   face_cnt;
> +     __u32   reserved[6];
> +};
> +
>  /*
>   *   I O C T L   C O D E S   F O R   V I D E O   D E V I C E S
>   *
> @@ -2254,6 +2322,8 @@ struct v4l2_create_buffers {
>     versions */
>  #define VIDIOC_CREATE_BUFS   _IOWR('V', 92, struct v4l2_create_buffers)
>  #define VIDIOC_PREPARE_BUF   _IOWR('V', 93, struct v4l2_buffer)
> +#define VIDIOC_G_FD_COUNT    _IOWR('V', 94, struct v4l2_fd_count)
> +#define VIDIOC_G_FD_RESULT   _IOWR('V', 95, struct v4l2_fd_result)
>  
>  /* Reminder: when adding new ioctls please add support for them to
>     drivers/media/video/v4l2-compat-ioctl32.c as well! */
> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> index 4d1c74a..19f03b0 100644
> --- a/include/media/v4l2-ioctl.h
> +++ b/include/media/v4l2-ioctl.h
> @@ -270,6 +270,12 @@ struct v4l2_ioctl_ops {
>       int (*vidioc_unsubscribe_event)(struct v4l2_fh *fh,
>                                       struct v4l2_event_subscription *sub);
>  
> +     /* Face detect IOCTLs */
> +     int (*vidioc_g_fd_count) (struct file *file, void *fh,
> +                                     struct v4l2_fd_count *arg);
> +     int (*vidioc_g_fd_result) (struct file *file, void *fh,
> +                                     struct v4l2_fd_result *arg);
> +
>       /* For other private ioctls */
>       long (*vidioc_default)         (struct file *file, void *fh,
>                                       bool valid_prio, int cmd, void *arg);
> -- 
> 1.7.5.4
> 
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-- 
Sakari Ailus
e-mail: sakari.ai...@iki.fi     jabber/XMPP/Gmail: sai...@retiisi.org.uk
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