Re: [RFC v2 6/8] media: uapi: Remove bit_size field from v4l2_ctrl_hevc_slice_params

[Benjamin Gaignard]

Le 15/02/2022 à 15:17, John Cox a écrit :
> Hi
>
> > The bit size of the slice could be deduced from the buffer payload
> > so remove bit_size field to avoid duplicated the information.
> I think this is a bad idea. In the future we are (I hope) going to want
> to have an array (variable) of slice headers all referring to the same
> bit buffer.  When we do that we will need this field.

I wonder if that could be considering like another decode mode and so
use an other control ?

> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > ---
> > .../userspace-api/media/v4l/ext-ctrls-codec.rst       |  3 ---
> > drivers/staging/media/sunxi/cedrus/cedrus_h265.c      | 11 ++++-------
> > include/uapi/linux/v4l2-controls.h                    |  3 +--
> > 3 files changed, 5 insertions(+), 12 deletions(-)
> >
> > diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> > index 3296ac3b9fca..c3ae97657fa7 100644
> > --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> > +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> > @@ -2965,9 +2965,6 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> >      :stub-columns: 0
> >      :widths:       1 1 2
> >
> > -    * - __u32
> > -      - ``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.
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > index 8ab2d9c6f048..db8c7475eeb8 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > @@ -312,8 +312,8 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
> > 	const struct v4l2_hevc_pred_weight_table *pred_weight_table;
> > 	unsigned int width_in_ctb_luma, ctb_size_luma;
> > 	unsigned int log2_max_luma_coding_block_size;
> > +	size_t slice_bytes;
> > 	dma_addr_t src_buf_addr;
> > -	dma_addr_t src_buf_end_addr;
> > 	u32 chroma_log2_weight_denom;
> > 	u32 output_pic_list_index;
> > 	u32 pic_order_cnt[2];
> > @@ -370,8 +370,8 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
> >
> > 	cedrus_write(dev, VE_DEC_H265_BITS_OFFSET, 0);
> >
> > -	reg = slice_params->bit_size;
> > -	cedrus_write(dev, VE_DEC_H265_BITS_LEN, reg);
> > +	slice_bytes = vb2_get_plane_payload(&run->src->vb2_buf, 0);
> > +	cedrus_write(dev, VE_DEC_H265_BITS_LEN, slice_bytes);
> I think one of these must be wrong. bit_size is in bits,
> vb2_get_plane_payload is in bytes?

You are right it should be vb2_get_plane_payload() * 8 to get the size in bits.

I will change that in v3.

> Regards
>
> John Cox
>   
> > 	/* Source beginning and end addresses. */
> >
> > @@ -384,10 +384,7 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
> >
> > 	cedrus_write(dev, VE_DEC_H265_BITS_ADDR, reg);
> >
> > -	src_buf_end_addr = src_buf_addr +
> > -			   DIV_ROUND_UP(slice_params->bit_size, 8);
> > -
> > -	reg = VE_DEC_H265_BITS_END_ADDR_BASE(src_buf_end_addr);
> > +	reg = VE_DEC_H265_BITS_END_ADDR_BASE(src_buf_addr + slice_bytes);
> > 	cedrus_write(dev, VE_DEC_H265_BITS_END_ADDR, reg);
> >
> > 	/* Coding tree block address */
> > diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> > index b1a3dc05f02f..27f5d272dc43 100644
> > --- a/include/uapi/linux/v4l2-controls.h
> > +++ b/include/uapi/linux/v4l2-controls.h
> > @@ -2457,7 +2457,6 @@ struct v4l2_hevc_pred_weight_table {
> > #define V4L2_HEVC_SLICE_PARAMS_FLAG_DEPENDENT_SLICE_SEGMENT	(1ULL << 9)
> >
> > struct v4l2_ctrl_hevc_slice_params {
> > -	__u32	bit_size;
> > 	__u32	data_bit_offset;
> >
> > 	/* ISO/IEC 23008-2, ITU-T Rec. H.265: NAL unit header */
> > @@ -2484,7 +2483,7 @@ struct v4l2_ctrl_hevc_slice_params {
> > 	/* ISO/IEC 23008-2, ITU-T Rec. H.265: Picture timing SEI message */
> > 	__u8	pic_struct;
> >
> > -	__u8	reserved;
> > +	__u8	reserved[5];
> >
> > 	/* ISO/IEC 23008-2, ITU-T Rec. H.265: General slice segment header */
> > 	__u32	slice_segment_addr;