Subsystem Trace Points: msm_low_power

The msm_low_power tracing system captures the events during the entry
and exit of various low power modes like power collapse, standalone
power collapse, retention and wfi. The tracing system adds the following
events to capture the state of the low power mode.

1) msm_pm_enter
===================
msm_pm_enter: cpu: %u latency: %uus sleep: %uus
msm_pm_enter_pc: cpu: %u latency: %uus sleep: %uus wake_up: %u
msm_pm_enter_ret: cpu: %u latency: %uus sleep: %uus wake_up: %u
msm_pm_enter_spc: cpu: %u latency: %uus sleep: %uus wake_up: %u
msm_pm_enter_wfi: cpu: %u latency: %uus sleep: %uus wake_up: %u

The event captures various parameters during the entry into low power
modes.

The 'cpu' parameter represents the cpu on which the low power mode is
chosen.

The 'latency_us' parameter represents the system latency at the time of
choosing the low power mode.

The 'sleep_us' parameter tells the maximum amount of time the kernel can
sleep in this low power mode.

The 'wake_up' parameter tells if there was any immediate wakeup required
before entering low power mode.

2) msm_pm_exit
=================
msm_pm_exit: cpu:%u success:%d
msm_pm_exit_pc: cpu:%u success:%d
msm_pm_exit_ret: cpu:%u success:%d
msm_pm_exit_spc: cpu:%u success:%d
msm_pm_exit_wfi: cpu:%u success:%d

The event captures parameters during the exit of the low power modes.

The 'cpu' parameter represents the cpu on which the low power mode is chosen.

The 'success' parameter shows the state of power collapse/standalone power
collapse. It will be set if power collapse/standalone power collapse were
successful. For the rest of the low power modes it is set to one.
