media: v4l2: Trace calculated p/b0/b1 initial reflist

Add debug print statements to print the content of P & B reference
lists, to verify that the ordering of the generated reference lists is
correct. This is especially important for the field decoding mode,
where sorting is more complex.
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/v4l2-core/v4l2-h264.c

@@ -12,6 +12,12 @@
 
 #include <media/v4l2-h264.h>
 
+/*
+ * Size of the tempory buffer allocated when printing reference lists. The
+ * output will be truncated if the size is too small.
+ */
+static const int tmp_str_size = 1024;
+
 /**
  * v4l2_h264_init_reflist_builder() - Initialize a P/B0/B1 reference list
  *				      builder
@@ -241,6 +247,95 @@ static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
 	return poca < pocb ? -1 : 1;
 }
 
+static char ref_type_to_char(u8 ref_type)
+{
+	switch (ref_type) {
+	case V4L2_H264_FRAME_REF:
+		return 'f';
+	case V4L2_H264_TOP_FIELD_REF:
+		return 't';
+	case V4L2_H264_BOTTOM_FIELD_REF:
+		return 'b';
+	}
+
+	return '?';
+}
+
+static const char *format_ref_list_p(const struct v4l2_h264_reflist_builder *builder,
+				     struct v4l2_h264_reference *reflist,
+				     char **out_str)
+{
+	int n = 0, i;
+
+	*out_str = kmalloc(tmp_str_size, GFP_KERNEL);
+
+	n += snprintf(*out_str + n, tmp_str_size - n, "|");
+
+	for (i = 0; i < builder->num_valid; i++) {
+		/* this is pic_num for frame and frame_num (wrapped) for field,
+		 * but for frame pic_num is equal to frame_num (wrapped).
+		 */
+		int frame_num = builder->refs[reflist[i].index].frame_num;
+		bool longterm = builder->refs[reflist[i].index].longterm;
+
+		n += scnprintf(*out_str + n, tmp_str_size - n, "%i%c%c|",
+			       frame_num, longterm ? 'l' : 's',
+			       ref_type_to_char(reflist[i].fields));
+	}
+
+	return *out_str;
+}
+
+static void print_ref_list_p(const struct v4l2_h264_reflist_builder *builder,
+			     struct v4l2_h264_reference *reflist)
+{
+	char *buf = NULL;
+
+	pr_debug("ref_pic_list_p (cur_poc %u%c) %s\n",
+		 builder->cur_pic_order_count,
+		 ref_type_to_char(builder->cur_pic_fields),
+		 format_ref_list_p(builder, reflist, &buf));
+
+	kfree(buf);
+}
+
+static const char *format_ref_list_b(const struct v4l2_h264_reflist_builder *builder,
+				     struct v4l2_h264_reference *reflist,
+				     char **out_str)
+{
+	int n = 0, i;
+
+	*out_str = kmalloc(tmp_str_size, GFP_KERNEL);
+
+	n += snprintf(*out_str + n, tmp_str_size - n, "|");
+
+	for (i = 0; i < builder->num_valid; i++) {
+		int frame_num = builder->refs[reflist[i].index].frame_num;
+		u32 poc = v4l2_h264_get_poc(builder, reflist + i);
+		bool longterm = builder->refs[reflist[i].index].longterm;
+
+		n += scnprintf(*out_str + n, tmp_str_size - n, "%i%c%c|",
+			       longterm ? frame_num : poc,
+			       longterm ? 'l' : 's',
+			       ref_type_to_char(reflist[i].fields));
+	}
+
+	return *out_str;
+}
+
+static void print_ref_list_b(const struct v4l2_h264_reflist_builder *builder,
+			     struct v4l2_h264_reference *reflist, u8 list_num)
+{
+	char *buf = NULL;
+
+	pr_debug("ref_pic_list_b%u (cur_poc %u%c) %s",
+		 list_num, builder->cur_pic_order_count,
+		 ref_type_to_char(builder->cur_pic_fields),
+		 format_ref_list_b(builder, reflist, &buf));
+
+	kfree(buf);
+}
+
 /**
  * v4l2_h264_build_p_ref_list() - Build the P reference list
  *
@@ -261,6 +356,8 @@ v4l2_h264_build_p_ref_list(const struct v4l2_h264_reflist_builder *builder,
 	       sizeof(builder->unordered_reflist[0]) * builder->num_valid);
 	sort_r(reflist, builder->num_valid, sizeof(*reflist),
 	       v4l2_h264_p_ref_list_cmp, NULL, builder);
+
+	print_ref_list_p(builder, reflist);
 }
 EXPORT_SYMBOL_GPL(v4l2_h264_build_p_ref_list);
 
@@ -296,6 +393,9 @@ v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
 	if (builder->num_valid > 1 &&
 	    !memcmp(b1_reflist, b0_reflist, builder->num_valid))
 		swap(b1_reflist[0], b1_reflist[1]);
+
+	print_ref_list_b(builder, b0_reflist, 0);
+	print_ref_list_b(builder, b1_reflist, 1);
 }
 EXPORT_SYMBOL_GPL(v4l2_h264_build_b_ref_lists);