Em Mon, 17 Feb 2014 10:57:19 +0100
Hans Verkuil <hverkuil@xxxxxxxxx> escreveu:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> Complex controls are controls that can be used for compound and array
> types. This allows for more complex data structures to be used with the
> control framework.
>
> Such controls always have the V4L2_CTRL_FLAG_HIDDEN flag set. Note that
> 'simple' controls can also set that flag.
>
> The existing V4L2_CTRL_FLAG_NEXT_CTRL flag will only enumerate controls
> that do not have the HIDDEN flag, so a new V4L2_CTRL_FLAG_NEXT_HIDDEN flag
> is added to enumerate hidden controls. Set both flags to enumerate any
> controls (hidden or not).
>
> Complex control types will start at V4L2_CTRL_COMPLEX_TYPES. In addition, any
> control that uses the new 'p' field or the existing 'string' field will have
> flag V4L2_CTRL_FLAG_IS_PTR set.
>
> While not strictly necessary, adding that flag makes life for applications
> a lot simpler. If the flag is not set, then the control value is set
> through the value or value64 fields of struct v4l2_ext_control, otherwise
> a pointer points to the value.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> Reviewed-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> ---
> include/uapi/linux/videodev2.h | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 6ae7bbe..4d7782a 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1228,6 +1228,7 @@ struct v4l2_ext_control {
> __s32 value;
> __s64 value64;
> char *string;
> + void *p;
Hmm... don't we have already "string" for pointers? Also, calling it
as "p" inside an userspace api doesn't seem to nice ("ptr" would be
better).
Btw, you likely already noticed the mess, as, when you added
this email's comment, you said that complex controls could
either use "p" or "string".
Nack. It should just use "string". Let's not add even more complexity
to this "complex" controls.
> };
> } __attribute__ ((packed));
>
> @@ -1252,7 +1253,10 @@ enum v4l2_ctrl_type {
> V4L2_CTRL_TYPE_CTRL_CLASS = 6,
> V4L2_CTRL_TYPE_STRING = 7,
> V4L2_CTRL_TYPE_BITMASK = 8,
> - V4L2_CTRL_TYPE_INTEGER_MENU = 9,
> + V4L2_CTRL_TYPE_INTEGER_MENU = 9,
> +
> + /* Complex types are >= 0x0100 */
> + V4L2_CTRL_COMPLEX_TYPES = 0x0100,
> };
Not sure if I got why you're calling it as "TYPES" and saying that
everything >= 0x100 is complex. What's your idea here?
Also, at least for me with my engineering formation, "complex"
means a number with an imaginary component.
And yes, we do have complex numbers on some usecases for
V4L (for example, SDR in-phase/quadrature, e. g. I/Q
representation can be seen as an array of complex numbers).
So, I won't doubt that someone might propose some day to add a
way to set a complex number via a V4L2 control.
So, please use a better naming here to avoid troubles.
> /* Used in the VIDIOC_QUERYCTRL ioctl for querying controls */
> @@ -1288,9 +1292,12 @@ struct v4l2_querymenu {
> #define V4L2_CTRL_FLAG_SLIDER 0x0020
> #define V4L2_CTRL_FLAG_WRITE_ONLY 0x0040
> #define V4L2_CTRL_FLAG_VOLATILE 0x0080
> +#define V4L2_CTRL_FLAG_HIDDEN 0x0100
> +#define V4L2_CTRL_FLAG_IS_PTR 0x0200
>
> -/* Query flag, to be ORed with the control ID */
> +/* Query flags, to be ORed with the control ID */
> #define V4L2_CTRL_FLAG_NEXT_CTRL 0x80000000
> +#define V4L2_CTRL_FLAG_NEXT_HIDDEN 0x40000000
>
> /* User-class control IDs defined by V4L2 */
> #define V4L2_CID_MAX_CTRLS 1024
--
Regards,
Mauro
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