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>
Bug: 325508361
(cherry picked from commit 015abee404760249a5c968b9ce29216b94b8ced1
https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git
linux-next)
Change-Id: Iad7cae74c41b23b430331379c180b5e59bc32c40
Signed-off-by: Vilas Bhat <vilasbhat@google.com>
ad49939193