Hi Daniel,
Sorry for the delay, it's been very busy lately...
On 26/06/2021 18:42, Daniel Almeida wrote:
> I am sending this again because apparently I sent it originally from my
> personal email by mistake.
>
> ---------------
>
>
> Hi Hans!
>
> I have been working on testing this lately as you know.
>
> From the example you've added to vivid, i.e.:
>
> +static const struct v4l2_ctrl_config vivid_ctrl_u32_dyn_array = {
> + .ops = &vivid_user_gen_ctrl_ops,
> + .id = VIVID_CID_U32_DYN_ARRAY,
> + .name = "U32 Dynamic Array",
> + .type = V4L2_CTRL_TYPE_U32,
> + .flags = V4L2_CTRL_FLAG_DYNAMIC_ARRAY,
> + .def = 50,
> + .min = 10,
> + .max = 90,
> + .step = 1,
> + .dims = { 100 },
> +};
> +
>
> + v4l2_ctrl_new_custom(hdl_user_gen, &vivid_ctrl_u32_dyn_array, NULL);
>
>
> I was under the impression that it'd be enough to pass the id and
> V4L2_CTRL_FLAG_DYNAMIC_ARRAY in the config before calling
> v4l2_ctrl_new_custom. Apparently that's not the case though, because
> v4l2_ctrl_fill will then set its own flags if I understood correctly, i.e.:
>
>
> if (name == NULL)
> v4l2_ctrl_fill(cfg->id, &name, &type, &min, &max, &step,
> &def,&flags)
v4l2_ctrl_fill doesn't know about custom controls. It only handles standard
controls. For custom controls you always need to fill in everything.
>
> <snip>
>
> *name = v4l2_ctrl_get_name(id);
> *flags = 0
>
>
> <snip>
>
>
> To be honest, I didn't quite understand whether you wanted individual
> drivers to signal they want to treat a given control as a dynamic array
> or whether I should add that flag in the switch statement in
> v4l2_ctrl_fill, thereby enabling this feature by default for all drivers
> that use that control if I understood correctly.
If a standard control (i.e. not a private driver control) is a dynamic array,
then that flag must be set in v4l2_ctrl_fill().
>
> If the former, I was expecting to communicate it to userspace via a menu
> control, e.g. for h264 and cedrus:
>
> enum v4l2_stateless_h264_decode_mode {
> V4L2_STATELESS_H264_DECODE_MODE_SLICE_BASED, /* i.e. a single
> slice per request */
> V4L2_STATELESS_H264_DECODE_MODE_FRAME_BASED,
> + V4L2_STATELESS_H264_DECODE_MODE_SLICE_ARRAY_BASED, /* i.e. an array
> of slices per request */
> };
>
> @@ -56,6 +56,7 @@ static const struct cedrus_control cedrus_controls[] = {
> {
> .cfg = {
> .id = V4L2_CID_STATELESS_H264_SLICE_PARAMS,
> + .flags = V4L2_CTRL_FLAG_DYNAMIC_ARRAY,
> },
> .codec = CEDRUS_CODEC_H264,
> },
> @@ -86,7 +87,7 @@ static const struct cedrus_control cedrus_controls[] = {
> {
> .cfg = {
> .id = V4L2_CID_STATELESS_H264_DECODE_MODE,
> - .max = V4L2_STATELESS_H264_DECODE_MODE_SLICE_BASED,
> + .max = V4L2_STATELESS_H264_DECODE_MODE_SLICE_ARRAY_BASED,
> .def = V4L2_STATELESS_H264_DECODE_MODE_SLICE_BASED,
> },
> .codec = CEDRUS_CODEC_H264,
>
> -- Daniel
>
If a driver supports arrays of slice params, then it will need to create a
new V4L2_CID_STATELESS_H264_SLICE_PARAMS_ARRAY control. You can't just change
V4L2_CID_STATELESS_H264_SLICE_PARAMS from a regular compound control to a
dynamic array control, they have to be different controls.
A driver can support either V4L2_CID_STATELESS_H264_SLICE_PARAMS,
V4L2_CID_STATELESS_H264_SLICE_PARAMS_ARRAY or both, with the corresponding modes
enumerated in V4L2_CID_STATELESS_H264_DECODE_MODE.
I hope this helps.
Regards,
Hans
