Re: [PATCH v10 09/17] media: uapi: HEVC: Define V4L2_CID_STATELESS_HEVC_SLICE_PARAMS as a dynamic array

[Ezequiel Garcia]

On Tue, Jul 05, 2022 at 10:54:12AM +0200, Benjamin Gaignard wrote:
> Make explicit that V4L2_CID_STATELESS_HEVC_SLICE_PARAMS control is
> a dynamic array control type.
> Some drivers may be able to receive multiple slices in one control
> to improve decoding performance.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> Acked-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
> Tested-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>

Reviewed-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxxxxxxx>

> ---
> version 9:
> - Add comment about current driver dynamic limitation to 1
> - Remove unused define
> 
>  Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst | 2 ++
>  drivers/media/v4l2-core/v4l2-ctrls-defs.c                 | 1 +
>  drivers/staging/media/sunxi/cedrus/cedrus.c               | 2 ++
>  include/media/hevc-ctrls.h                                | 3 +++
>  4 files changed, 8 insertions(+)
> 
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index eeb60c9a1af4..db0df7d9f27c 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -2986,6 +2986,8 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
>      These bitstream parameters are defined according to :ref:`hevc`.
>      They are described in section 7.4.7 "General slice segment header
>      semantics" of the specification.
> +    This control is a dynamically sized 1-dimensional array,
> +    V4L2_CTRL_FLAG_DYNAMIC_ARRAY flag must be set when using it.
>  
>  .. c:type:: v4l2_ctrl_hevc_slice_params
>  
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> index 9f55503cd3d6..d594efbcbb93 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> @@ -1510,6 +1510,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>  		break;
>  	case V4L2_CID_STATELESS_HEVC_SLICE_PARAMS:
>  		*type = V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS;
> +		*flags |= V4L2_CTRL_FLAG_DYNAMIC_ARRAY;
>  		break;
>  	case V4L2_CID_STATELESS_HEVC_SCALING_MATRIX:
>  		*type = V4L2_CTRL_TYPE_HEVC_SCALING_MATRIX;
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c b/drivers/staging/media/sunxi/cedrus/cedrus.c
> index 87be975a72b6..b12219123a6b 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus.c
> @@ -178,6 +178,8 @@ static const struct cedrus_control cedrus_controls[] = {
>  	{
>  		.cfg = {
>  			.id	= V4L2_CID_STATELESS_HEVC_SLICE_PARAMS,
> +			/* The driver can only handle 1 entry per slice for now */
> +			.dims   = { 1 },
>  		},
>  		.codec		= CEDRUS_CODEC_H265,
>  	},
> diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
> index 57053cfa099b..341fc795d550 100644
> --- a/include/media/hevc-ctrls.h
> +++ b/include/media/hevc-ctrls.h
> @@ -314,6 +314,9 @@ struct v4l2_hevc_pred_weight_table {
>  /**
>   * struct v4l2_ctrl_hevc_slice_params - HEVC slice parameters
>   *
> + * This control is a dynamically sized 1-dimensional array,
> + * V4L2_CTRL_FLAG_DYNAMIC_ARRAY flag must be set when using it.
> + *
>   * @bit_size: size (in bits) of the current slice data
>   * @data_bit_offset: offset (in bits) to the video data in the current slice data
>   * @nal_unit_type: specifies the coding type of the slice (B, P or I)
> -- 
> 2.32.0
>