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Subject: Re: [PATCH 03/10] media: uapi: h264: Split prediction weight
 parameters
To:     Ezequiel Garcia <ezequiel@collabora.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Tomasz Figa <tfiga@chromium.org>, kernel@collabora.com,
        Jonas Karlman <jonas@kwiboo.se>,
        Alexandre Courbot <acourbot@chromium.org>,
        Jeffrey Kardatzke <jkardatzke@chromium.org>,
        Nicolas Dufresne <nicolas.dufresne@collabora.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Maxime Ripard <mripard@kernel.org>,
        Paul Kocialkowski <paul.kocialkowski@bootlin.com>
References: <20200715202233.185680-1-ezequiel@collabora.com>
 <20200715202233.185680-4-ezequiel@collabora.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
Message-ID: <15cd77f2-30ac-8d23-1be1-e9a58d85c088@xs4all.nl>
Date:   Thu, 16 Jul 2020 09:26:19 +0200
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On 15/07/2020 22:22, Ezequiel Garcia wrote:
> The prediction weight parameters are only required under
> certain conditions, which depend on slice header parameters.
> 
> The slice header syntax specifies that the prediction
> weight table is present if:
> 
> ((weighted_pred_flag && (slice_type == P || slice_type == SP)) || \
> (weighted_bipred_idc == 1 && slice_type == B))
> 
> Given its size, it makes sense to move this table to its control,
> so applications can avoid passing it if the slice doesn't specify it.
> 
> Before this change struct v4l2_ctrl_h264_slice_params was 960 bytes.
> With this change, it's 188 bytes and struct v4l2_ctrl_h264_pred_weight
> is 772 bytes.
> 
> Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
> ---
>  .../userspace-api/media/v4l/ext-ctrls-codec.rst    | 14 +++++++++-----
>  drivers/media/v4l2-core/v4l2-ctrls.c               |  6 ++++++
>  drivers/staging/media/sunxi/cedrus/cedrus.h        |  1 +
>  drivers/staging/media/sunxi/cedrus/cedrus_dec.c    |  2 ++
>  drivers/staging/media/sunxi/cedrus/cedrus_h264.c   |  6 ++----
>  include/media/h264-ctrls.h                         |  5 +++--
>  6 files changed, 23 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index 16bfc98ab2f6..d1695ae96700 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -1879,18 +1879,22 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>        - 0x00000008
>        -
>  
> -``Prediction Weight Table``
> -
> -    The bitstream parameters are defined according to :ref:`h264`,
> +``V4L2_CID_MPEG_VIDEO_H264_PRED_WEIGHT (struct)``
> +    Prediction weight table defined according to :ref:`h264`,
>      section 7.4.3.2 "Prediction Weight Table Semantics". For further
>      documentation, refer to the above specification, unless there is
>      an explicit comment stating otherwise.
>  
> -.. c:type:: v4l2_h264_pred_weight_table
> +    .. note::
> +
> +       This compound control is not yet part of the public kernel API and
> +       it is expected to change.
> +
> +.. c:type:: v4l2_ctrl_h264_pred_weight
>  
>  .. cssclass:: longtable
>  
> -.. flat-table:: struct v4l2_h264_pred_weight_table
> +.. flat-table:: struct v4l2_ctrl_h264_pred_weight
>      :header-rows:  0
>      :stub-columns: 0
>      :widths:       1 1 2
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index 3f3fbcd60cc6..3a8a23e34c70 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -1412,6 +1412,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>  	case V4L2_CID_MPEG_VIDEO_H264_DECODE_PARAMS:
>  		*type = V4L2_CTRL_TYPE_H264_DECODE_PARAMS;
>  		break;
> +	case V4L2_CID_MPEG_VIDEO_H264_PRED_WEIGHT:
> +		*type = V4L2_CTRL_TYPE_H264_PRED_WEIGHT;
> +		break;
>  	case V4L2_CID_MPEG_VIDEO_VP8_FRAME_HEADER:
>  		*type = V4L2_CTRL_TYPE_VP8_FRAME_HEADER;
>  		break;
> @@ -2553,6 +2556,9 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
>  	case V4L2_CTRL_TYPE_H264_DECODE_PARAMS:
>  		elem_size = sizeof(struct v4l2_ctrl_h264_decode_params);
>  		break;
> +	case V4L2_CTRL_TYPE_H264_PRED_WEIGHT:
> +		elem_size = sizeof(struct v4l2_ctrl_h264_pred_weight);
> +		break;
>  	case V4L2_CTRL_TYPE_VP8_FRAME_HEADER:
>  		elem_size = sizeof(struct v4l2_ctrl_vp8_frame_header);
>  		break;
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.h b/drivers/staging/media/sunxi/cedrus/cedrus.h
> index 96765555ab8a..80a0ecffa384 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus.h
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus.h
> @@ -62,6 +62,7 @@ struct cedrus_h264_run {
>  	const struct v4l2_ctrl_h264_scaling_matrix	*scaling_matrix;
>  	const struct v4l2_ctrl_h264_slice_params	*slice_params;
>  	const struct v4l2_ctrl_h264_sps			*sps;
> +	const struct v4l2_ctrl_h264_pred_weight		*pred_weight;
>  };
>  
>  struct cedrus_mpeg2_run {
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> index 58c48e4fdfe9..047f773f64f9 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> @@ -57,6 +57,8 @@ void cedrus_device_run(void *priv)
>  			V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS);
>  		run.h264.sps = cedrus_find_control_data(ctx,
>  			V4L2_CID_MPEG_VIDEO_H264_SPS);
> +		run.h264.pred_weight = cedrus_find_control_data(ctx,
> +			V4L2_CID_MPEG_VIDEO_H264_PRED_WEIGHT);
>  		break;
>  
>  	case V4L2_PIX_FMT_HEVC_SLICE:
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> index cce527bbdf86..614b1b496e40 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> @@ -256,10 +256,8 @@ static void cedrus_write_scaling_lists(struct cedrus_ctx *ctx,
>  static void cedrus_write_pred_weight_table(struct cedrus_ctx *ctx,
>  					   struct cedrus_run *run)
>  {
> -	const struct v4l2_ctrl_h264_slice_params *slice =
> -		run->h264.slice_params;
> -	const struct v4l2_h264_pred_weight_table *pred_weight =
> -		&slice->pred_weight_table;
> +	const struct v4l2_ctrl_h264_pred_weight *pred_weight =
> +		run->h264.pred_weight;
>  	struct cedrus_dev *dev = ctx->dev;
>  	int i, j, k;
>  
> diff --git a/include/media/h264-ctrls.h b/include/media/h264-ctrls.h
> index bca4a9887e7e..da2ffb77b491 100644
> --- a/include/media/h264-ctrls.h
> +++ b/include/media/h264-ctrls.h
> @@ -36,6 +36,7 @@
>  #define V4L2_CID_MPEG_VIDEO_H264_DECODE_PARAMS	(V4L2_CID_MPEG_BASE+1004)
>  #define V4L2_CID_MPEG_VIDEO_H264_DECODE_MODE	(V4L2_CID_MPEG_BASE+1005)
>  #define V4L2_CID_MPEG_VIDEO_H264_START_CODE	(V4L2_CID_MPEG_BASE+1006)
> +#define V4L2_CID_MPEG_VIDEO_H264_PRED_WEIGHT	(V4L2_CID_MPEG_BASE+1007)
>  
>  /* enum v4l2_ctrl_type type values */
>  #define V4L2_CTRL_TYPE_H264_SPS			0x0110
> @@ -43,6 +44,7 @@
>  #define V4L2_CTRL_TYPE_H264_SCALING_MATRIX	0x0112
>  #define V4L2_CTRL_TYPE_H264_SLICE_PARAMS	0x0113
>  #define V4L2_CTRL_TYPE_H264_DECODE_PARAMS	0x0114
> +#define V4L2_CTRL_TYPE_H264_PRED_WEIGHT		0x0115
>  
>  enum v4l2_mpeg_video_h264_decode_mode {
>  	V4L2_MPEG_VIDEO_H264_DECODE_MODE_SLICE_BASED,
> @@ -125,7 +127,7 @@ struct v4l2_h264_weight_factors {
>  	__s16 chroma_offset[32][2];
>  };
>  
> -struct v4l2_h264_pred_weight_table {
> +struct v4l2_ctrl_h264_pred_weight {
>  	__u16 luma_log2_weight_denom;
>  	__u16 chroma_log2_weight_denom;
>  	struct v4l2_h264_weight_factors weight_factors[2];
> @@ -174,7 +176,6 @@ struct v4l2_ctrl_h264_slice_params {
>  	__s32 delta_pic_order_cnt0;
>  	__s32 delta_pic_order_cnt1;
>  
> -	struct v4l2_h264_pred_weight_table pred_weight_table;
>  	/* Size in bits of dec_ref_pic_marking() syntax element. */
>  	__u32 dec_ref_pic_marking_bit_size;
>  	/* Size in bits of pic order count syntax. */
> 

Shouldn't this be added to union v4l2_ctrl_ptr as well?

Regards,

	Hans