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

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Date:   Mon, 16 Dec 2019 16:16:50 +0000
From:   lukasz.luba@....com
To:     linux-kernel@...r.kernel.org, sudeep.holla@....com,
        linux-arm-kernel@...ts.infradead.org
Cc:     rostedt@...dmis.org, mingo@...hat.com,
        Lukasz Luba <lukasz.luba@....com>
Subject: [PATCH 2/2] drivers: firmware: scmi: Extend SCMI transport layer by trace events

From: Lukasz Luba <lukasz.luba@....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.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 drivers/firmware/arm_scmi/driver.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 3eb0382491ce..0fda9b418bc6 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)
@@ -439,6 +442,9 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	if (unlikely(!cinfo))
 		return -EINVAL;
 
+	trace_scmi_xfer_begin(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 +484,9 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	 */
 	mbox_client_txdone(cinfo->chan, ret);
 
+	trace_scmi_xfer_end(xfer->hdr.id, xfer->hdr.protocol_id, xfer->hdr.seq,
+			    xfer->hdr.status);
+
 	return ret;
 }
 
-- 
2.17.1