[RFC][PATCH 09/10] v4l: Export enums used by tracepoints to user space

[Steven Rostedt]

From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>

Enums used by tracepoints for __print_symbolic() are shown in the
tracepoint format files with just their names and not their values.
This makes it difficult for user space tools to know how to convert the
binary data into their string representations.

By adding the use of TRACE_DEFINE_ENUM(), the enum names will be mapped
to their values and shown in the tracing file system to let tools
convert the data as necessary.

Cc: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 include/trace/events/v4l2.h | 75 ++++++++++++++++++++++++++++++---------------
 1 file changed, 50 insertions(+), 25 deletions(-)

diff --git a/include/trace/events/v4l2.h b/include/trace/events/v4l2.h
index b9bb1f204693..d96a0eadcb1d 100644
--- a/include/trace/events/v4l2.h
+++ b/include/trace/events/v4l2.h
@@ -6,33 +6,58 @@
 
 #include <linux/tracepoint.h>
 
-#define show_type(type)							       \
-	__print_symbolic(type,						       \
-		{ V4L2_BUF_TYPE_VIDEO_CAPTURE,	      "VIDEO_CAPTURE" },       \
-		{ V4L2_BUF_TYPE_VIDEO_OUTPUT,	      "VIDEO_OUTPUT" },	       \
-		{ V4L2_BUF_TYPE_VIDEO_OVERLAY,	      "VIDEO_OVERLAY" },       \
-		{ V4L2_BUF_TYPE_VBI_CAPTURE,	      "VBI_CAPTURE" },	       \
-		{ V4L2_BUF_TYPE_VBI_OUTPUT,	      "VBI_OUTPUT" },	       \
-		{ V4L2_BUF_TYPE_SLICED_VBI_CAPTURE,   "SLICED_VBI_CAPTURE" },  \
-		{ V4L2_BUF_TYPE_SLICED_VBI_OUTPUT,    "SLICED_VBI_OUTPUT" },   \
-		{ V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY, "VIDEO_OUTPUT_OVERLAY" },\
-		{ V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE, "VIDEO_CAPTURE_MPLANE" },\
-		{ V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE,  "VIDEO_OUTPUT_MPLANE" }, \
-		{ V4L2_BUF_TYPE_SDR_CAPTURE,          "SDR_CAPTURE" },         \
-		{ V4L2_BUF_TYPE_PRIVATE,	      "PRIVATE" })
+/* Enums require being exported to userspace, for user tool parsing */
+#undef EM
+#undef EMe
+#define EM(a, b)	TRACE_DEFINE_ENUM(a);
+#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
+
+#define show_type(type)							\
+	__print_symbolic(type, SHOW_TYPE)
+
+#define SHOW_TYPE							\
+	EM( V4L2_BUF_TYPE_VIDEO_CAPTURE,	"VIDEO_CAPTURE" )	\
+	EM( V4L2_BUF_TYPE_VIDEO_OUTPUT,		"VIDEO_OUTPUT" )	\
+	EM( V4L2_BUF_TYPE_VIDEO_OVERLAY,	"VIDEO_OVERLAY" )	\
+	EM( V4L2_BUF_TYPE_VBI_CAPTURE,		"VBI_CAPTURE" )		\
+	EM( V4L2_BUF_TYPE_VBI_OUTPUT,		"VBI_OUTPUT" )		\
+	EM( V4L2_BUF_TYPE_SLICED_VBI_CAPTURE,   "SLICED_VBI_CAPTURE" )	\
+	EM( V4L2_BUF_TYPE_SLICED_VBI_OUTPUT,    "SLICED_VBI_OUTPUT" )	\
+	EM( V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY, "VIDEO_OUTPUT_OVERLAY" ) \
+	EM( V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE, "VIDEO_CAPTURE_MPLANE" ) \
+	EM( V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE,  "VIDEO_OUTPUT_MPLANE" )	\
+	EM( V4L2_BUF_TYPE_SDR_CAPTURE,          "SDR_CAPTURE" )		\
+	EMe(V4L2_BUF_TYPE_PRIVATE,		"PRIVATE" )
+
+SHOW_TYPE
 
 #define show_field(field)						\
-	__print_symbolic(field,						\
-		{ V4L2_FIELD_ANY,		"ANY" },		\
-		{ V4L2_FIELD_NONE,		"NONE" },		\
-		{ V4L2_FIELD_TOP,		"TOP" },		\
-		{ V4L2_FIELD_BOTTOM,		"BOTTOM" },		\
-		{ V4L2_FIELD_INTERLACED,	"INTERLACED" },		\
-		{ V4L2_FIELD_SEQ_TB,		"SEQ_TB" },		\
-		{ V4L2_FIELD_SEQ_BT,		"SEQ_BT" },		\
-		{ V4L2_FIELD_ALTERNATE,		"ALTERNATE" },		\
-		{ V4L2_FIELD_INTERLACED_TB,	"INTERLACED_TB" },      \
-		{ V4L2_FIELD_INTERLACED_BT,	"INTERLACED_BT" })
+	__print_symbolic(field, SHOW_FIELD
+
+#define SHOW_FIELD							\
+	EM( V4L2_FIELD_ANY,		"ANY" )				\
+	EM( V4L2_FIELD_NONE,		"NONE" )			\
+	EM( V4L2_FIELD_TOP,		"TOP" )				\
+	EM( V4L2_FIELD_BOTTOM,		"BOTTOM" )			\
+	EM( V4L2_FIELD_INTERLACED,	"INTERLACED" )			\
+	EM( V4L2_FIELD_SEQ_TB,		"SEQ_TB" )			\
+	EM( V4L2_FIELD_SEQ_BT,		"SEQ_BT" )			\
+	EM( V4L2_FIELD_ALTERNATE,	"ALTERNATE" )			\
+	EM( V4L2_FIELD_INTERLACED_TB,	"INTERLACED_TB" )		\
+	EMe( V4L2_FIELD_INTERLACED_BT,	"INTERLACED_BT" )
+
+SHOW_FIELD
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings
+ * that will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	{a, b},
+#define EMe(a, b)	{a, b}
+
+/* V4L2_TC_TYPE_* are macros, not defines, they do not need processing */
 
 #define show_timecode_type(type)					\
 	__print_symbolic(type,						\
-- 
2.1.4


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