[PATCH v3] cpuidle: psci: Add trace for PSCI domain idle

[Keita Morisaki <keyz@google.com>]

The trace event cpu_idle provides insufficient information for debugging
PSCI requests due to lacking access to determined PSCI domain idle
states. The cpu_idle usually only shows -1, 0, or 1 regardless how many
idle states the power domain has.

Add new trace events namely psci_domain_idle_enter and
psci_domain_idle_exit to trace enter and exit events with a determined
idle state.

These new trace events will help developers debug CPUidle issues on ARM
systems using PSCI by providing more detailed information about the
requested idle states.

Signed-off-by: Keita Morisaki <keyz@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
v1->v2: Split the ftrace event into two (psci_domain_idle_(enter|exit))
        and rephrase the commit message accordingly. Rebased onto the latest.
v2->v3: Add the Reviewed-by label

 drivers/cpuidle/cpuidle-psci.c |  3 +++
 include/trace/events/power.h   | 37 ++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index 2562dc001fc1..dd8d776d6e39 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -25,6 +25,7 @@
 #include <linux/syscore_ops.h>

 #include <asm/cpuidle.h>
+#include <trace/events/power.h>

 #include "cpuidle-psci.h"
 #include "dt_idle_states.h"
@@ -74,7 +75,9 @@ static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 	if (!state)
 		state = states[idx];

+	trace_psci_domain_idle_enter(dev->cpu, state, s2idle);
 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
+	trace_psci_domain_idle_exit(dev->cpu, state, s2idle);

 	if (s2idle)
 		dev_pm_genpd_resume(pd_dev);
diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index d2349b6b531a..9253e83b9bb4 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -62,6 +62,43 @@ TRACE_EVENT(cpu_idle_miss,
 		(unsigned long)__entry->state, (__entry->below)?"below":"above")
 );

+DECLARE_EVENT_CLASS(psci_domain_idle,
+
+	TP_PROTO(unsigned int cpu_id, unsigned int state, bool s2idle),
+
+	TP_ARGS(cpu_id, state, s2idle),
+
+	TP_STRUCT__entry(
+		__field(u32,		cpu_id)
+		__field(u32,		state)
+		__field(bool,		s2idle)
+	),
+
+	TP_fast_assign(
+		__entry->cpu_id = cpu_id;
+		__entry->state = state;
+		__entry->s2idle = s2idle;
+	),
+
+	TP_printk("cpu_id=%lu state=0x%lx is_s2idle=%s",
+		  (unsigned long)__entry->cpu_id, (unsigned long)__entry->state,
+		  (__entry->s2idle)?"yes":"no")
+);
+
+DEFINE_EVENT(psci_domain_idle, psci_domain_idle_enter,
+
+	TP_PROTO(unsigned int cpu_id, unsigned int state, bool s2idle),
+
+	TP_ARGS(cpu_id, state, s2idle)
+);
+
+DEFINE_EVENT(psci_domain_idle, psci_domain_idle_exit,
+
+	TP_PROTO(unsigned int cpu_id, unsigned int state, bool s2idle),
+
+	TP_ARGS(cpu_id, state, s2idle)
+);
+
 TRACE_EVENT(powernv_throttle,

 	TP_PROTO(int chip_id, const char *reason, int pmax),

base-commit: ffd294d346d185b70e28b1a28abe367bbfe53c04
--
2.48.1.262.g85cc9f2d1e-goog