Re: [PATCH v8 14/17] media: hantro: Stop using Hantro dedicated control

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

Le mardi 14 juin 2022 à 15:58 +0200, Hans Verkuil a écrit :
> On 6/14/22 10:36, Benjamin Gaignard wrote:
> > The number of bits to skip in the slice header can be computed
> > in the driver by using sps, pps and decode_params information.
> > This allow to remove Hantro dedicated control.
> 
> allow -> makes it possible
> 
> > 
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> > ---
> >  drivers/staging/media/hantro/hantro_drv.c     | 36 -----------
> >  .../staging/media/hantro/hantro_g2_hevc_dec.c | 62 ++++++++++++++++++-
> >  include/media/hevc-ctrls.h                    | 13 ----
> >  3 files changed, 61 insertions(+), 50 deletions(-)
> > 
> > diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
> > index 536c8c374952..5aac3a090480 100644
> > --- a/drivers/staging/media/hantro/hantro_drv.c
> > +++ b/drivers/staging/media/hantro/hantro_drv.c
> > @@ -304,26 +304,6 @@ static int hantro_jpeg_s_ctrl(struct v4l2_ctrl *ctrl)
> >  	return 0;
> >  }
> >  
> > -static int hantro_hevc_s_ctrl(struct v4l2_ctrl *ctrl)
> > -{
> > -	struct hantro_ctx *ctx;
> > -
> > -	ctx = container_of(ctrl->handler,
> > -			   struct hantro_ctx, ctrl_handler);
> > -
> > -	vpu_debug(1, "s_ctrl: id = %d, val = %d\n", ctrl->id, ctrl->val);
> > -
> > -	switch (ctrl->id) {
> > -	case V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP:
> > -		ctx->hevc_dec.ctrls.hevc_hdr_skip_length = ctrl->val;
> > -		break;
> > -	default:
> > -		return -EINVAL;
> > -	}
> > -
> > -	return 0;
> > -}
> > -
> >  static const struct v4l2_ctrl_ops hantro_ctrl_ops = {
> >  	.try_ctrl = hantro_try_ctrl,
> >  };
> > @@ -332,10 +312,6 @@ static const struct v4l2_ctrl_ops hantro_jpeg_ctrl_ops = {
> >  	.s_ctrl = hantro_jpeg_s_ctrl,
> >  };
> >  
> > -static const struct v4l2_ctrl_ops hantro_hevc_ctrl_ops = {
> > -	.s_ctrl = hantro_hevc_s_ctrl,
> > -};
> > -
> >  #define HANTRO_JPEG_ACTIVE_MARKERS	(V4L2_JPEG_ACTIVE_MARKER_APP0 | \
> >  					 V4L2_JPEG_ACTIVE_MARKER_COM | \
> >  					 V4L2_JPEG_ACTIVE_MARKER_DQT | \
> > @@ -487,18 +463,6 @@ static const struct hantro_ctrl controls[] = {
> >  		.cfg = {
> >  			.id = V4L2_CID_STATELESS_HEVC_SCALING_MATRIX,
> >  		},
> > -	}, {
> > -		.codec = HANTRO_HEVC_DECODER,
> > -		.cfg = {
> > -			.id = V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP,
> > -			.name = "Hantro HEVC slice header skip bytes",
> > -			.type = V4L2_CTRL_TYPE_INTEGER,
> > -			.min = 0,
> > -			.def = 0,
> > -			.max = 0x100,
> > -			.step = 1,
> > -			.ops = &hantro_hevc_ctrl_ops,
> > -		},
> >  	}, {
> >  		.codec = HANTRO_VP9_DECODER,
> >  		.cfg = {
> > diff --git a/drivers/staging/media/hantro/hantro_g2_hevc_dec.c b/drivers/staging/media/hantro/hantro_g2_hevc_dec.c
> > index d28653d04d20..3be8d6e60bf0 100644
> > --- a/drivers/staging/media/hantro/hantro_g2_hevc_dec.c
> > +++ b/drivers/staging/media/hantro/hantro_g2_hevc_dec.c
> > @@ -117,6 +117,66 @@ static void prepare_tile_info_buffer(struct hantro_ctx *ctx)
> >  		vpu_debug(1, "%s: no chroma!\n", __func__);
> >  }
> >  
> > +static unsigned int ceil_log2(unsigned int v)
> > +{
> > +	/* Compute Ceil(Log2(v))
> > +	 * Derived from branchless code for integer log2(v) from:
> > +	 * <http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog>
> > +	 */
> > +	unsigned int r, shift;
> > +
> > +	v--;
> > +	r = (v > 0xFFFF) << 4;
> > +	v >>= r;
> > +	shift = (v > 0xFF) << 3;
> > +	v >>= shift;
> > +	r |= shift;
> > +	shift = (v > 0xF) << 2;
> > +	v >>= shift;
> > +	r |= shift;
> > +	shift = (v > 0x3) << 1;
> > +	v >>= shift;
> > +	r |= shift;
> > +	r |= (v >> 1);
> > +
> > +	return r + 1;
> > +}
> 
> Isn't this identical to fls(v - 1)? See also lib/math/reciprocal_div.c
> where this is used.

Thanks for pointing this out, I was wondering if there was an equivalent, and
never knew there was a relation between log2() and the "last set bit". Not sure
about the -1 here though, can you extend ?

> 
> Regards,
> 
> 	Hans
> 
> > +
> > +static int compute_header_skip_lenght(struct hantro_ctx *ctx)
> > +{
> > +	const struct hantro_hevc_dec_ctrls *ctrls = &ctx->hevc_dec.ctrls;
> > +	const struct v4l2_ctrl_hevc_decode_params *decode_params = ctrls->decode_params;
> > +	const struct v4l2_ctrl_hevc_sps *sps = ctrls->sps;
> > +	const struct v4l2_ctrl_hevc_pps *pps = ctrls->pps;
> > +	int skip = 0;
> > +
> > +	if (pps->flags & V4L2_HEVC_PPS_FLAG_OUTPUT_FLAG_PRESENT)
> > +		/* size of pic_output_flag */
> > +		skip++;
> > +
> > +	if (sps->flags & V4L2_HEVC_SPS_FLAG_SEPARATE_COLOUR_PLANE)
> > +		/* size of pic_order_cnt_lsb */
> > +		skip += 2;
> > +
> > +	if (!(decode_params->flags & V4L2_HEVC_DECODE_PARAM_FLAG_IDR_PIC)) {
> > +		/* size of pic_order_cnt_lsb */
> > +		skip += sps->log2_max_pic_order_cnt_lsb_minus4 + 4;
> > +
> > +		/* size of short_term_ref_pic_set_sps_flag */
> > +		skip++;
> > +
> > +		if (decode_params->short_term_ref_pic_set_size)
> > +			/* size of st_ref_pic_set( num_short_term_ref_pic_sets ) */
> > +			skip += decode_params->short_term_ref_pic_set_size;
> > +		else if (sps->num_short_term_ref_pic_sets > 1)
> > +			skip += ceil_log2(sps->num_short_term_ref_pic_sets);
> > +
> > +		skip += decode_params->long_term_ref_pic_set_size;
> > +	}
> > +
> > +	return skip;
> > +}
> > +
> >  static void set_params(struct hantro_ctx *ctx)
> >  {
> >  	const struct hantro_hevc_dec_ctrls *ctrls = &ctx->hevc_dec.ctrls;
> > @@ -134,7 +194,7 @@ static void set_params(struct hantro_ctx *ctx)
> >  
> >  	hantro_reg_write(vpu, &g2_output_8_bits, 0);
> >  
> > -	hantro_reg_write(vpu, &g2_hdr_skip_length, ctrls->hevc_hdr_skip_length);
> > +	hantro_reg_write(vpu, &g2_hdr_skip_length, compute_header_skip_lenght(ctx));
> >  
> >  	min_log2_cb_size = sps->log2_min_luma_coding_block_size_minus3 + 3;
> >  	max_log2_ctb_size = min_log2_cb_size + sps->log2_diff_max_min_luma_coding_block_size;
> > diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
> > index d6cb3779d190..efc0412ac41e 100644
> > --- a/include/media/hevc-ctrls.h
> > +++ b/include/media/hevc-ctrls.h
> > @@ -467,17 +467,4 @@ struct v4l2_ctrl_hevc_scaling_matrix {
> >  	__u8	scaling_list_dc_coef_32x32[2];
> >  };
> >  
> > -/*  MPEG-class control IDs specific to the Hantro driver as defined by V4L2 */
> > -#define V4L2_CID_CODEC_HANTRO_BASE				(V4L2_CTRL_CLASS_CODEC | 0x1200)
> > -/*
> > - * V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP -
> > - * the number of data (in bits) to skip in the
> > - * slice segment header.
> > - * If non-IDR, the bits to be skipped go from syntax element "pic_output_flag"
> > - * to before syntax element "slice_temporal_mvp_enabled_flag".
> > - * If IDR, the skipped bits are just "pic_output_flag"
> > - * (separate_colour_plane_flag is not supported).
> > - */
> > -#define V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP	(V4L2_CID_CODEC_HANTRO_BASE + 0)
> > -
> >  #endif
>