media: rkvdec: h264: Fix dpb_valid implementation

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.

Fixes: cd33c83044 ("media: rkvdec: Add the rkvdec driver")
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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);