media: hantro: h264: Make dpb entry management more robust

The driver maintains stable slot locations for reference pictures. This
change makes the code more robust by using the reference_ts as key and
by marking all entries invalid right from the start.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/staging/media/hantro/hantro_h264.c

@@ -258,8 +258,7 @@ static void prepare_table(struct hantro_ctx *ctx)
 static bool dpb_entry_match(const struct v4l2_h264_dpb_entry *a,
 			    const struct v4l2_h264_dpb_entry *b)
 {
-	return a->top_field_order_cnt == b->top_field_order_cnt &&
-	       a->bottom_field_order_cnt == b->bottom_field_order_cnt;
+	return a->reference_ts == b->reference_ts;
 }
 
 static void update_dpb(struct hantro_ctx *ctx)
@@ -273,13 +272,13 @@ static void update_dpb(struct hantro_ctx *ctx)
 
 	/* Disable all entries by default. */
 	for (i = 0; i < ARRAY_SIZE(ctx->h264_dec.dpb); i++)
-		ctx->h264_dec.dpb[i].flags &= ~V4L2_H264_DPB_ENTRY_FLAG_ACTIVE;
+		ctx->h264_dec.dpb[i].flags = 0;
 
 	/* Try to match new DPB entries with existing ones by their POCs. */
 	for (i = 0; i < ARRAY_SIZE(dec_param->dpb); i++) {
 		const struct v4l2_h264_dpb_entry *ndpb = &dec_param->dpb[i];
 
-		if (!(ndpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
+		if (!(ndpb->flags & V4L2_H264_DPB_ENTRY_FLAG_VALID))
 			continue;
 
 		/*
@@ -290,8 +289,7 @@ static void update_dpb(struct hantro_ctx *ctx)
 			struct v4l2_h264_dpb_entry *cdpb;
 
 			cdpb = &ctx->h264_dec.dpb[j];
-			if (cdpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE ||
-			    !dpb_entry_match(cdpb, ndpb))
+			if (!dpb_entry_match(cdpb, ndpb))
 				continue;
 
 			*cdpb = *ndpb;