Re: [PATCH v10 16/17] media: uapi: Change data_bit_offset definition

[Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>]

On Tue, Jul 05, 2022 at 10:54:19AM +0200, Benjamin Gaignard wrote:
> 'F.7.3.6.1 General slice segment header syntax' section of HEVC
> specification describes that a slice header always end aligned on
> byte boundary, therefore we only need to provide the data offset in bytes.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> Acked-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> Tested-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Makes sense and it matches what other CODEC ABIs.

Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>

Thanks,
Ezequiel

> ---
>  .../media/v4l/ext-ctrls-codec.rst             |  4 ++--
>  .../staging/media/sunxi/cedrus/cedrus_h265.c  | 19 ++++++++++++++++++-
>  .../staging/media/sunxi/cedrus/cedrus_video.c |  1 -
>  include/media/hevc-ctrls.h                    |  4 ++--
>  4 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index 889e2bcffde6..af5cb4e4ef73 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -3008,8 +3008,8 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
>        - ``bit_size``
>        - Size (in bits) of the current slice data.
>      * - __u32
> -      - ``data_bit_offset``
> -      - Offset (in bits) to the video data in the current slice data.
> +      - ``data_byte_offset``
> +      - Offset (in bytes) to the video data in the current slice data.
>      * - __u32
>        - ``num_entry_point_offsets``
>        - Specifies the number of entry point offset syntax elements in the slice header.
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> index 411601975124..7b67cb4621cf 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> @@ -317,6 +317,8 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
>  	u32 chroma_log2_weight_denom;
>  	u32 output_pic_list_index;
>  	u32 pic_order_cnt[2];
> +	u8 *padding;
> +	int count;
>  	u32 reg;
>  
>  	sps = run->h265.sps;
> @@ -405,7 +407,22 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
>  	/* Initialize bitstream access. */
>  	cedrus_write(dev, VE_DEC_H265_TRIGGER, VE_DEC_H265_TRIGGER_INIT_SWDEC);
>  
> -	cedrus_h265_skip_bits(dev, slice_params->data_bit_offset);
> +	/*
> +	 * Cedrus expects that bitstream pointer is actually at the end of the slice header
> +	 * instead of start of slice data. Padding is 8 bits at most (one bit set to 1 and
> +	 * at most seven bits set to 0), so we have to inspect only one byte before slice data.
> +	 */
> +	padding = (u8 *)vb2_plane_vaddr(&run->src->vb2_buf, 0) +
> +		slice_params->data_byte_offset - 1;
> +
> +	for (count = 0; count < 8; count++)
> +		if (*padding & (1 << count))
> +			break;
> +
> +	/* Include the one bit. */
> +	count++;
> +
> +	cedrus_h265_skip_bits(dev, slice_params->data_byte_offset * 8 - count);
>  
>  	/* Bitstream parameters. */
>  
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_video.c b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> index 33726175d980..66714609b577 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> @@ -568,7 +568,6 @@ int cedrus_queue_init(void *priv, struct vb2_queue *src_vq,
>  
>  	src_vq->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
>  	src_vq->io_modes = VB2_MMAP | VB2_DMABUF;
> -	src_vq->dma_attrs = DMA_ATTR_NO_KERNEL_MAPPING;
>  	src_vq->drv_priv = ctx;
>  	src_vq->buf_struct_size = sizeof(struct cedrus_buffer);
>  	src_vq->ops = &cedrus_qops;
> diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
> index 7358cbfc3e4d..c89029b3c5da 100644
> --- a/include/media/hevc-ctrls.h
> +++ b/include/media/hevc-ctrls.h
> @@ -310,7 +310,7 @@ struct v4l2_hevc_pred_weight_table {
>   * 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
> + * @data_byte_offset: offset (in bytes) to the video data in the current slice data
>   * @num_entry_point_offsets: specifies the number of entry point offset syntax
>   *			     elements in the slice header.
>   * @nal_unit_type: specifies the coding type of the slice (B, P or I)
> @@ -356,7 +356,7 @@ struct v4l2_hevc_pred_weight_table {
>   */
>  struct v4l2_ctrl_hevc_slice_params {
>  	__u32	bit_size;
> -	__u32	data_bit_offset;
> +	__u32	data_byte_offset;
>  	__u32	num_entry_point_offsets;
>  	/* ISO/IEC 23008-2, ITU-T Rec. H.265: NAL unit header */
>  	__u8	nal_unit_type;
> -- 
> 2.32.0
>