Received-SPF: pass (google.com: domain of linux-kernel+bounces-75132-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Wed, 21 Feb 2024 16:41:10 +0000
Precedence: bulk
Mime-Version: 1.0
Message-ID: <20240221164112.846409-1-vilasbhat@google.com>
Subject: [PATCH v1] PM: runtime: add tracepoint for runtime_status changes
From: Vilas Bhat <vilasbhat@google.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>, Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Steven Rostedt <rostedt@goodmis.org>, 
	Masami Hiramatsu <mhiramat@kernel.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Vilas Bhat <vilasbhat@google.com>, Saravana Kannan <saravanak@google.com>, kernel-team@android.com, 
	linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-trace-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

Existing runtime PM ftrace events (`rpm_suspend`, `rpm_resume`,
`rpm_return_int`) offer limited visibility into the exact timing of device
runtime power state transitions, particularly when asynchronous operations
are involved. When the `rpm_suspend` or `rpm_resume` functions are invoked
with the `RPM_ASYNC` flag, a return value of 0 i.e., success merely
indicates that the device power state request has been queued, not that
the device has yet transitioned.

A new ftrace event, `rpm_status`, is introduced. This event directly logs
the `power.runtime_status` value of a device whenever it changes providing
granular tracking of runtime power state transitions regardless of
synchronous or asynchronous `rpm_suspend` / `rpm_resume` usage.

Signed-off-by: Vilas Bhat <vilasbhat@google.com>
---
 drivers/base/power/runtime.c |  1 +
 include/trace/events/rpm.h   | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 05793c9fbb84..d10354847878 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -94,6 +94,7 @@ static void update_pm_runtime_accounting(struct device *dev)
 static void __update_runtime_status(struct device *dev, enum rpm_status status)
 {
 	update_pm_runtime_accounting(dev);
+	trace_rpm_status(dev, status);
 	dev->power.runtime_status = status;
 }
 
diff --git a/include/trace/events/rpm.h b/include/trace/events/rpm.h
index 3c716214dab1..f1dc4e95dbce 100644
--- a/include/trace/events/rpm.h
+++ b/include/trace/events/rpm.h
@@ -101,6 +101,42 @@ TRACE_EVENT(rpm_return_int,
 		__entry->ret)
 );
 
+#define RPM_STATUS_STRINGS \
+	{ RPM_INVALID, "RPM_INVALID" }, \
+	{ RPM_ACTIVE, "RPM_ACTIVE" }, \
+	{ RPM_RESUMING, "RPM_RESUMING" }, \
+	{ RPM_SUSPENDED, "RPM_SUSPENDED" }, \
+	{ RPM_SUSPENDING, "RPM_SUSPENDING" }
+
+/*
+ * ftrace's __print_symbolic requires that all enum values be wrapped in the
+ * TRACE_DEFINE_ENUM macro so that the enum value can be encoded in the ftrace
+ * ring buffer.
+ */
+TRACE_DEFINE_ENUM(RPM_INVALID);
+TRACE_DEFINE_ENUM(RPM_ACTIVE);
+TRACE_DEFINE_ENUM(RPM_RESUMING);
+TRACE_DEFINE_ENUM(RPM_SUSPENDED);
+TRACE_DEFINE_ENUM(RPM_SUSPENDING);
+
+TRACE_EVENT(rpm_status,
+	TP_PROTO(struct device *dev, enum rpm_status status),
+	TP_ARGS(dev, status),
+
+	TP_STRUCT__entry(
+		__string(name,	dev_name(dev))
+		__field(int,	status)
+	),
+
+	TP_fast_assign(
+		__assign_str(name, dev_name(dev));
+		__entry->status = status;
+	),
+
+	TP_printk("%s status=%s", __get_str(name),
+		__print_symbolic(__entry->status, RPM_STATUS_STRINGS))
+);
+
 #endif /* _TRACE_RUNTIME_POWER_H */
 
 /* This part must be outside protection */
-- 
2.44.0.rc0.258.g7320e95886-goog