PM / QoS: Add pm_qos and dev_pm_qos to events-power.txt

Add PM QOS events section and description to events-power.txt.
Signed-off-by: NSahara <keun-o.park@windriver.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/trace/events-power.txt

@@ -63,3 +63,34 @@ power_domain_target	"%s state=%lu cpu_id=%lu"
 The first parameter gives the power domain name (e.g. "mpu_pwrdm").
 The second parameter is the power domain target state.
 
+4. PM QoS events
+================
+The PM QoS events are used for QoS add/update/remove request and for
+target/flags update.
+
+pm_qos_add_request                 "pm_qos_class=%s value=%d"
+pm_qos_update_request              "pm_qos_class=%s value=%d"
+pm_qos_remove_request              "pm_qos_class=%s value=%d"
+pm_qos_update_request_timeout      "pm_qos_class=%s value=%d, timeout_us=%ld"
+
+The first parameter gives the QoS class name (e.g. "CPU_DMA_LATENCY").
+The second parameter is value to be added/updated/removed.
+The third parameter is timeout value in usec.
+
+pm_qos_update_target               "action=%s prev_value=%d curr_value=%d"
+pm_qos_update_flags                "action=%s prev_value=0x%x curr_value=0x%x"
+
+The first parameter gives the QoS action name (e.g. "ADD_REQ").
+The second parameter is the previous QoS value.
+The third parameter is the current QoS value to update.
+
+And, there are also events used for device PM QoS add/update/remove request.
+
+dev_pm_qos_add_request             "device=%s type=%s new_value=%d"
+dev_pm_qos_update_request          "device=%s type=%s new_value=%d"
+dev_pm_qos_remove_request          "device=%s type=%s new_value=%d"
+
+The first parameter gives the device name which tries to add/update/remove
+QoS requests.
+The second parameter gives the request type (e.g. "DEV_PM_QOS_LATENCY").
+The third parameter is value to be added/updated/removed.