Re: [PATCH v2 13/23] media: rkvdec: h264: Fix dpb_valid implementation

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

On Thu, Mar 31, 2022 at 03:37:15PM -0400, Nicolas Dufresne wrote:
> The ref builder only provided references that are marked as valid in the
> dpb. Thus the current implementation of dpb_valid would always set the
> flag to 1. This is not representing missing frames (this is called
> 'non-existing' pictures in the spec). In some context, these non-existing
> pictures still need to occupy a slot in the reference list according to
> the spec.
> 

Good catch! OOC, did you find this because it was failing a test vector?

> Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>

Fixes: cd33c830448ba ("media: rkvdec: Add the rkvdec driver")
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>

Thanks,
Ezequiel

> ---
>  drivers/staging/media/rkvdec/rkvdec-h264.c | 33 ++++++++++++++++------
>  1 file changed, 24 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/staging/media/rkvdec/rkvdec-h264.c b/drivers/staging/media/rkvdec/rkvdec-h264.c
> index dff89732ddd0..bcde37d72244 100644
> --- a/drivers/staging/media/rkvdec/rkvdec-h264.c
> +++ b/drivers/staging/media/rkvdec/rkvdec-h264.c
> @@ -112,6 +112,7 @@ struct rkvdec_h264_run {
>  	const struct v4l2_ctrl_h264_sps *sps;
>  	const struct v4l2_ctrl_h264_pps *pps;
>  	const struct v4l2_ctrl_h264_scaling_matrix *scaling_matrix;
> +	int ref_buf_idx[V4L2_H264_NUM_DPB_ENTRIES];
>  };
>  
>  struct rkvdec_h264_ctx {
> @@ -725,6 +726,26 @@ static void assemble_hw_pps(struct rkvdec_ctx *ctx,
>  	}
>  }
>  
> +static void lookup_ref_buf_idx(struct rkvdec_ctx *ctx,
> +			       struct rkvdec_h264_run *run)
> +{
> +	const struct v4l2_ctrl_h264_decode_params *dec_params = run->decode_params;
> +	u32 i;
> +
> +	for (i = 0; i < ARRAY_SIZE(dec_params->dpb); i++) {
> +		struct v4l2_m2m_ctx *m2m_ctx = ctx->fh.m2m_ctx;
> +		const struct v4l2_h264_dpb_entry *dpb = run->decode_params->dpb;
> +		struct vb2_queue *cap_q = &m2m_ctx->cap_q_ctx.q;
> +		int buf_idx = -1;
> +
> +		if (dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE)
> +			buf_idx = vb2_find_timestamp(cap_q,
> +						     dpb[i].reference_ts, 0);
> +
> +		run->ref_buf_idx[i] = buf_idx;
> +	}
> +}
> +
>  static void assemble_hw_rps(struct rkvdec_ctx *ctx,
>  			    struct rkvdec_h264_run *run)
>  {
> @@ -762,7 +783,7 @@ static void assemble_hw_rps(struct rkvdec_ctx *ctx,
>  
>  	for (j = 0; j < RKVDEC_NUM_REFLIST; j++) {
>  		for (i = 0; i < h264_ctx->reflists.num_valid; i++) {
> -			u8 dpb_valid = 0;
> +			bool dpb_valid = run->ref_buf_idx[i] >= 0;
>  			u8 idx = 0;
>  
>  			switch (j) {
> @@ -779,8 +800,6 @@ static void assemble_hw_rps(struct rkvdec_ctx *ctx,
>  
>  			if (idx >= ARRAY_SIZE(dec_params->dpb))
>  				continue;
> -			dpb_valid = !!(dpb[idx].flags &
> -				       V4L2_H264_DPB_ENTRY_FLAG_ACTIVE);
>  
>  			set_ps_field(hw_rps, DPB_INFO(i, j),
>  				     idx | dpb_valid << 4);
> @@ -859,13 +878,8 @@ get_ref_buf(struct rkvdec_ctx *ctx, struct rkvdec_h264_run *run,
>  	    unsigned int dpb_idx)
>  {
>  	struct v4l2_m2m_ctx *m2m_ctx = ctx->fh.m2m_ctx;
> -	const struct v4l2_h264_dpb_entry *dpb = run->decode_params->dpb;
>  	struct vb2_queue *cap_q = &m2m_ctx->cap_q_ctx.q;
> -	int buf_idx = -1;
> -
> -	if (dpb[dpb_idx].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE)
> -		buf_idx = vb2_find_timestamp(cap_q,
> -					     dpb[dpb_idx].reference_ts, 0);
> +	int buf_idx = run->ref_buf_idx[dpb_idx];
>  
>  	/*
>  	 * If a DPB entry is unused or invalid, address of current destination
> @@ -1102,6 +1116,7 @@ static int rkvdec_h264_run(struct rkvdec_ctx *ctx)
>  
>  	assemble_hw_scaling_list(ctx, &run);
>  	assemble_hw_pps(ctx, &run);
> +	lookup_ref_buf_idx(ctx, &run);
>  	assemble_hw_rps(ctx, &run);
>  	config_registers(ctx, &run);
>  
> -- 
> 2.34.1
>