[PATCH v2 1/2] include: trace: Add SCMI header with trace events

[PATCH v2 1/2] include: trace: Add SCMI header with trace events

[lukasz.luba]

From: Lukasz Luba <lukasz.luba@arm.com>

Adding trace events would help to measure the speed of the communication
channel. It can be also potentially used helpful during investigation
of some issues platforms which use different transport layer.

Update also MAINTAINERS file with information that the new trace events
are maintained.

Suggested-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 MAINTAINERS                 |  1 +
 include/trace/events/scmi.h | 90 +++++++++++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 include/trace/events/scmi.h

diff --git a/MAINTAINERS b/MAINTAINERS
index cc0a4a8ae06a..0182315226fc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15966,6 +15966,7 @@ F:	drivers/firmware/arm_scpi.c
 F:	drivers/firmware/arm_scmi/
 F:	drivers/reset/reset-scmi.c
 F:	include/linux/sc[mp]i_protocol.h
+F:	include/trace/events/scmi.h
 
 SYSTEM RESET/SHUTDOWN DRIVERS
 M:	Sebastian Reichel <sre@kernel.org>
diff --git a/include/trace/events/scmi.h b/include/trace/events/scmi.h
new file mode 100644
index 000000000000..f076c430d243
--- /dev/null
+++ b/include/trace/events/scmi.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM scmi
+
+#if !defined(_TRACE_SCMI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SCMI_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(scmi_xfer_begin,
+	TP_PROTO(int transfer_id, u8 msg_id, u8 protocol_id, u16 seq,
+		 bool poll),
+	TP_ARGS(transfer_id, msg_id, protocol_id, seq, poll),
+
+	TP_STRUCT__entry(
+		__field(int, transfer_id)
+		__field(u8, msg_id)
+		__field(u8, protocol_id)
+		__field(u16, seq)
+		__field(bool, poll)
+	),
+
+	TP_fast_assign(
+		__entry->transfer_id = transfer_id;
+		__entry->msg_id = msg_id;
+		__entry->protocol_id = protocol_id;
+		__entry->seq = seq;
+		__entry->poll = poll;
+	),
+
+	TP_printk("transfer_id=%d msg_id=%u protocol_id=%u seq=%u poll=%u",
+		__entry->transfer_id, __entry->msg_id, __entry->protocol_id,
+		__entry->seq, __entry->poll)
+);
+
+TRACE_EVENT(scmi_xfer_end,
+	TP_PROTO(int transfer_id, u8 msg_id, u8 protocol_id, u16 seq,
+		 u32 status),
+	TP_ARGS(transfer_id, msg_id, protocol_id, seq, status),
+
+	TP_STRUCT__entry(
+		__field(int, transfer_id)
+		__field(u8, msg_id)
+		__field(u8, protocol_id)
+		__field(u16, seq)
+		__field(u32, status)
+	),
+
+	TP_fast_assign(
+		__entry->transfer_id = transfer_id;
+		__entry->msg_id = msg_id;
+		__entry->protocol_id = protocol_id;
+		__entry->seq = seq;
+		__entry->status = status;
+	),
+
+	TP_printk("transfer_id=%d msg_id=%u protocol_id=%u seq=%u status=%u",
+		__entry->transfer_id, __entry->msg_id, __entry->protocol_id,
+		__entry->seq, __entry->status)
+);
+
+TRACE_EVENT(scmi_rx_done,
+	TP_PROTO(int transfer_id, u8 msg_id, u8 protocol_id, u16 seq,
+		 u8 msg_type),
+	TP_ARGS(transfer_id, msg_id, protocol_id, seq, msg_type),
+
+	TP_STRUCT__entry(
+		__field(int, transfer_id)
+		__field(u8, msg_id)
+		__field(u8, protocol_id)
+		__field(u16, seq)
+		__field(u8, msg_type)
+	),
+
+	TP_fast_assign(
+		__entry->transfer_id = transfer_id;
+		__entry->msg_id = msg_id;
+		__entry->protocol_id = protocol_id;
+		__entry->seq = seq;
+		__entry->msg_type = msg_type;
+	),
+
+	TP_printk("transfer_id=%d msg_id=%u protocol_id=%u seq=%u msg_type=%u",
+		__entry->transfer_id, __entry->msg_id, __entry->protocol_id,
+		__entry->seq, __entry->msg_type)
+);
+#endif /* _TRACE_SCMI_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
2.17.1


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[PATCH v2 2/2] drivers: firmware: scmi: Extend SCMI transport layer by trace events

[lukasz.luba]

From: Lukasz Luba <lukasz.luba@arm.com>

The SCMI transport layer communicates via mailboxes and shared memory with
firmware running on a microcontroller. It is platform specific how long it
takes to pass a SCMI message. The most sensitive requests are coming from
CPUFreq subsystem, which might be used by the scheduler.
Thus, there is a need to measure these delays and capture anomalies.
This change introduces trace events wrapped around transfer code.

According to Jim's suggestion a unique transfer_id is to distinguish
similar entries which might have the same message id, protocol id and
sequence. This is a case then there are some timeouts in transfers.

Suggested-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 drivers/firmware/arm_scmi/common.h |  2 ++
 drivers/firmware/arm_scmi/driver.c | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 5237c2ff79fe..df35358ff324 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -81,6 +81,7 @@ struct scmi_msg {
 /**
  * struct scmi_xfer - Structure representing a message flow
  *
+ * @transfer_id: Unique ID for debug & profiling purpose
  * @hdr: Transmit message header
  * @tx: Transmit message
  * @rx: Receive message, the buffer should be pre-allocated to store
@@ -90,6 +91,7 @@ struct scmi_msg {
  * @async: pointer to delayed response message received event completion
  */
 struct scmi_xfer {
+	int transfer_id;
 	struct scmi_msg_hdr hdr;
 	struct scmi_msg tx;
 	struct scmi_msg rx;
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 3eb0382491ce..15c5629ad2cd 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -29,6 +29,9 @@
 
 #include "common.h"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/scmi.h>
+
 #define MSG_ID_MASK		GENMASK(7, 0)
 #define MSG_XTRACT_ID(hdr)	FIELD_GET(MSG_ID_MASK, (hdr))
 #define MSG_TYPE_MASK		GENMASK(9, 8)
@@ -61,6 +64,8 @@ enum scmi_error_codes {
 static LIST_HEAD(scmi_list);
 /* Protection for the entire list */
 static DEFINE_MUTEX(scmi_list_mutex);
+/* Track the unique id for the transfers for debug & profiling purpose */
+static atomic_t transfer_last_id;
 
 /**
  * struct scmi_xfers_info - Structure to manage transfer information
@@ -304,6 +309,7 @@ static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle,
 	xfer = &minfo->xfer_block[xfer_id];
 	xfer->hdr.seq = xfer_id;
 	reinit_completion(&xfer->done);
+	xfer->transfer_id = atomic_inc_return(&transfer_last_id);
 
 	return xfer;
 }
@@ -374,6 +380,10 @@ static void scmi_rx_callback(struct mbox_client *cl, void *m)
 
 	scmi_fetch_response(xfer, mem);
 
+	trace_scmi_rx_done(xfer->transfer_id, xfer->hdr.id,
+			   xfer->hdr.protocol_id, xfer->hdr.seq,
+			   msg_type);
+
 	if (msg_type == MSG_TYPE_DELAYED_RESP)
 		complete(xfer->async_done);
 	else
@@ -439,6 +449,10 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	if (unlikely(!cinfo))
 		return -EINVAL;
 
+	trace_scmi_xfer_begin(xfer->transfer_id, xfer->hdr.id,
+			      xfer->hdr.protocol_id, xfer->hdr.seq,
+			      xfer->hdr.poll_completion);
+
 	ret = mbox_send_message(cinfo->chan, xfer);
 	if (ret < 0) {
 		dev_dbg(dev, "mbox send fail %d\n", ret);
@@ -478,6 +492,10 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	 */
 	mbox_client_txdone(cinfo->chan, ret);
 
+	trace_scmi_xfer_end(xfer->transfer_id, xfer->hdr.id,
+			    xfer->hdr.protocol_id, xfer->hdr.seq,
+			    xfer->hdr.status);
+
 	return ret;
 }
 
-- 
2.17.1


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Re: [PATCH v2 1/2] include: trace: Add SCMI header with trace events

[Sudeep Holla]

On Tue, Dec 17, 2019 at 01:43:44PM +0000, lukasz.luba@arm.com wrote:
> From: Lukasz Luba <lukasz.luba@arm.com>
>
> Adding trace events would help to measure the speed of the communication
> channel. It can be also potentially used helpful during investigation
> of some issues platforms which use different transport layer.
>
> Update also MAINTAINERS file with information that the new trace events
> are maintained.
>

Applied both the patches for v5.6

--
Regards,
Sudeep

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