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PM: runtime: add tracepoint for runtime_status changes 

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>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Vilas Bhat 2024-02-21 19:47:53 +00:00 committed by Rafael J. Wysocki
parent b7d46644e5
commit 015abee404
2 changed files with 43 additions and 0 deletions
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1
drivers/base/power/runtime.c
View File

@ -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;
}

42
include/trace/events/rpm.h
View File

@ -101,6 +101,48 @@ TRACE_EVENT(rpm_return_int,
__entry->ret)
);
#define RPM_STATUS_STRINGS \
EM(RPM_INVALID, "RPM_INVALID") \
EM(RPM_ACTIVE, "RPM_ACTIVE") \
EM(RPM_RESUMING, "RPM_RESUMING") \
EM(RPM_SUSPENDED, "RPM_SUSPENDED") \
EMe(RPM_SUSPENDING, "RPM_SUSPENDING")
/* Enums require being exported to userspace, for user tool parsing. */
#undef EM
#undef EMe
#define EM(a, b) TRACE_DEFINE_ENUM(a);
#define EMe(a, b) TRACE_DEFINE_ENUM(a);
RPM_STATUS_STRINGS
/*
* Now redefine the EM() and EMe() macros to map the enums to the strings that
* will be printed in the output.
*/
#undef EM
#undef EMe
#define EM(a, b) { a, b },
#define EMe(a, b) { a, b }
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 */