media: cedrus: h264: Properly configure reference field

When interlaced H264 content is being decoded, references must indicate
which field is being referenced. Currently this was done by checking
capture buffer flags. However, that is not correct because capture
buffer may hold both fields.

Fix this by checking newly introduced flags in reference lists.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/sunxi/cedrus/cedrus_h264.c

@@ -182,7 +182,6 @@ static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
 	for (i = 0; i < num_ref; i++) {
 		const struct v4l2_h264_dpb_entry *dpb;
 		const struct cedrus_buffer *cedrus_buf;
-		const struct vb2_v4l2_buffer *ref_buf;
 		unsigned int position;
 		int buf_idx;
 		u8 dpb_idx;
@@ -197,12 +196,11 @@ static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
 		if (buf_idx < 0)
 			continue;
 
-		ref_buf = to_vb2_v4l2_buffer(cap_q->bufs[buf_idx]);
-		cedrus_buf = vb2_v4l2_to_cedrus_buffer(ref_buf);
+		cedrus_buf = vb2_to_cedrus_buffer(cap_q->bufs[buf_idx]);
 		position = cedrus_buf->codec.h264.position;
 
 		sram_array[i] |= position << 1;
-		if (ref_buf->field == V4L2_FIELD_BOTTOM)
+		if (ref_list[i].fields & V4L2_H264_BOTTOM_FIELD_REF)
 			sram_array[i] |= BIT(0);
 	}