This patch is adding trace events for each request that is being
enqueued into the hw and will be completed. This way it is possible
to track the fill status of the gadget hardware and find potential
issues.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>

---
v5 -> v6:
 - fixed compile rule as module
 - reordered header files
v1 -> v5:
 - new patch
---
 drivers/usb/gadget/function/Makefile    |  3 ++
 drivers/usb/gadget/function/uvc_trace.c | 11 ++++++
 drivers/usb/gadget/function/uvc_trace.h | 60 +++++++++++++++++++++++++++++++++
 drivers/usb/gadget/function/uvc_video.c |  5 +++
 4 files changed, 79 insertions(+)

diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
index 87917a7d4a9be..92b695388611b 100644
--- a/drivers/usb/gadget/function/Makefile
+++ b/drivers/usb/gadget/function/Makefile
@@ -41,6 +41,9 @@ obj-$(CONFIG_USB_F_UAC1_LEGACY)	+= usb_f_uac1_legacy.o
 usb_f_uac2-y			:= f_uac2.o
 obj-$(CONFIG_USB_F_UAC2)	+= usb_f_uac2.o
 usb_f_uvc-y			:= f_uvc.o uvc_queue.o uvc_v4l2.o uvc_video.o uvc_configfs.o
+ifneq ($(CONFIG_TRACING),)
+    usb_f_uvc-y			+= uvc_trace.o
+endif
 obj-$(CONFIG_USB_F_UVC)		+= usb_f_uvc.o
 usb_f_midi-y			:= f_midi.o
 obj-$(CONFIG_USB_F_MIDI)	+= usb_f_midi.o
diff --git a/drivers/usb/gadget/function/uvc_trace.c b/drivers/usb/gadget/function/uvc_trace.c
new file mode 100644
index 0000000000000..d384f6d8221a5
--- /dev/null
+++ b/drivers/usb/gadget/function/uvc_trace.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace.c - USB UVC Gadget Trace Support
+ *
+ * Copyright (C) 2024 Pengutronix e.K.
+ *
+ * Author: Michael Grzeschik <m.grzeschik@pengutronix.de>
+ */
+
+#define CREATE_TRACE_POINTS
+#include "uvc_trace.h"
diff --git a/drivers/usb/gadget/function/uvc_trace.h b/drivers/usb/gadget/function/uvc_trace.h
new file mode 100644
index 0000000000000..04c33cf43cc2d
--- /dev/null
+++ b/drivers/usb/gadget/function/uvc_trace.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * trace.h - USB UVC Gadget Trace Support
+ *
+ * Copyright (C) 2024 Pengutronix e.K.
+ *
+ * Author: Michael Grzeschik <m.grzeschik@pengutronix.de>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM uvcg
+
+#if !defined(__UVCG_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __UVCG_TRACE_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+#include <linux/usb/gadget.h>
+#include <asm/byteorder.h>
+
+DECLARE_EVENT_CLASS(uvcg_video_req,
+	TP_PROTO(struct usb_request *req, u32 queued),
+	TP_ARGS(req, queued),
+	TP_STRUCT__entry(
+		__field(struct usb_request *, req)
+		__field(u32, length)
+		__field(u32, queued)
+	),
+	TP_fast_assign(
+		__entry->req = req;
+		__entry->length = req->length;
+		__entry->queued = queued;
+	),
+	TP_printk("req %p length %u queued %u",
+		__entry->req,
+		__entry->length,
+		__entry->queued)
+);
+
+DEFINE_EVENT(uvcg_video_req, uvcg_video_complete,
+	TP_PROTO(struct usb_request *req, u32 queued),
+	TP_ARGS(req, queued)
+);
+
+DEFINE_EVENT(uvcg_video_req, uvcg_video_queue,
+	TP_PROTO(struct usb_request *req, u32 queued),
+	TP_ARGS(req, queued)
+);
+
+#endif /* __UVCG_TRACE_H */
+
+/* this part has to be here */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE uvc_trace
+
+#include <trace/define_trace.h>
diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index 0287a56fa50ad..115524b79ebd7 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -19,6 +19,7 @@
 #include "uvc.h"
 #include "uvc_queue.h"
 #include "uvc_video.h"
+#include "uvc_trace.h"
 
 /* --------------------------------------------------------------------------
  * Video codecs
@@ -271,6 +272,8 @@ static int uvcg_video_ep_queue(struct uvc_video *video, struct usb_request *req)
 
 	atomic_inc(&video->queued);
 
+	trace_uvcg_video_queue(req, atomic_read(&video->queued));
+
 	return ret;
 }
 
@@ -408,6 +411,8 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 	 */
 	queue_work(video->async_wq, &video->pump);
 
+	trace_uvcg_video_complete(req, atomic_read(&video->queued));
+
 	spin_unlock_irqrestore(&video->req_lock, flags);
 
 	kthread_queue_work(video->kworker, &video->hw_submit);

-- 
2.39.5