9 files changed, 163 insertions, 145 deletions

diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt
index 3035d00757ad..425c51d56aef 100644
--- a/Documentation/power/opp.txt
+++ b/Documentation/power/opp.txt
@@ -1,6 +1,5 @@
-*=============*
-* OPP Library *
-*=============*
+Operating Performance Points (OPP) Library
+==========================================
 
 (C) 2009-2010 Nishanth Menon <nm@ti.com>, Texas Instruments Incorporated
 
@@ -16,15 +15,31 @@ Contents
 
 1. Introduction
 ===============
+1.1 What is an Operating Performance Point (OPP)?
+
 Complex SoCs of today consists of a multiple sub-modules working in conjunction.
 In an operational system executing varied use cases, not all modules in the SoC
 need to function at their highest performing frequency all the time. To
 facilitate this, sub-modules in a SoC are grouped into domains, allowing some
-domains to run at lower voltage and frequency while other domains are loaded
-more. The set of discrete tuples consisting of frequency and voltage pairs that
+domains to run at lower voltage and frequency while other domains run at
+voltage/frequency pairs that are higher.
+
+The set of discrete tuples consisting of frequency and voltage pairs that
 the device will support per domain are called Operating Performance Points or
 OPPs.
 
+As an example:
+Let us consider an MPU device which supports the following:
+{300MHz at minimum voltage of 1V}, {800MHz at minimum voltage of 1.2V},
+{1GHz at minimum voltage of 1.3V}
+
+We can represent these as three OPPs as the following {Hz, uV} tuples:
+{300000000, 1000000}
+{800000000, 1200000}
+{1000000000, 1300000}
+
+1.2 Operating Performance Points Library
+
 OPP library provides a set of helper functions to organize and query the OPP
 information. The library is located in drivers/base/power/opp.c and the header
 is located in include/linux/opp.h. OPP library can be enabled by enabling
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 2b7f77d3fcb0..15beb500a4e4 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -99,7 +99,6 @@ void device_pm_add(struct device *dev)
                 dev_warn(dev, "parent %s should not be sleeping\n",
                         dev_name(dev->parent));
         list_add_tail(&dev->power.entry, &dpm_list);
-        dev_pm_qos_constraints_init(dev);
         mutex_unlock(&dpm_list_mtx);
 }
 
@@ -113,7 +112,6 @@ void device_pm_remove(struct device *dev)
                  dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
         complete_all(&dev->power.completion);
         mutex_lock(&dpm_list_mtx);
-        dev_pm_qos_constraints_destroy(dev);
         list_del_init(&dev->power.entry);
         mutex_unlock(&dpm_list_mtx);
         device_wakeup_disable(dev);
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index b16686a0a5a2..cfc3226ec492 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -4,7 +4,7 @@ static inline void device_pm_init_common(struct device *dev)
 {
         if (!dev->power.early_init) {
                 spin_lock_init(&dev->power.lock);
-                dev->power.power_state = PMSG_INVALID;
+                dev->power.qos = NULL;
                 dev->power.early_init = true;
         }
 }
@@ -56,14 +56,10 @@ extern void device_pm_move_last(struct device *);
 
 static inline void device_pm_sleep_init(struct device *dev) {}
 
-static inline void device_pm_add(struct device *dev)
-{
-        dev_pm_qos_constraints_init(dev);
-}
+static inline void device_pm_add(struct device *dev) {}
 
 static inline void device_pm_remove(struct device *dev)
 {
-        dev_pm_qos_constraints_destroy(dev);
         pm_runtime_remove(dev);
 }
 
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 3d4d1f8aac5c..5f74587ef258 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -41,6 +41,7 @@
 #include <linux/mutex.h>
 #include <linux/export.h>
 #include <linux/pm_runtime.h>
+#include <linux/err.h>
 
 #include "power.h"
 
@@ -61,7 +62,7 @@ enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask)
         struct pm_qos_flags *pqf;
         s32 val;
 
-        if (!qos)
+        if (IS_ERR_OR_NULL(qos))
                 return PM_QOS_FLAGS_UNDEFINED;
 
         pqf = &qos->flags;
@@ -101,7 +102,8 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_flags);
  */
 s32 __dev_pm_qos_read_value(struct device *dev)
 {
-        return dev->power.qos ? pm_qos_read_value(&dev->power.qos->latency) : 0;
+        return IS_ERR_OR_NULL(dev->power.qos) ?
+                0 : pm_qos_read_value(&dev->power.qos->latency);
 }
 
 /**
@@ -198,20 +200,8 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
         return 0;
 }
 
-/**
- * dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer.
- * @dev: target device
- *
- * Called from the device PM subsystem during device insertion under
- * device_pm_lock().
- */
-void dev_pm_qos_constraints_init(struct device *dev)
-{
-        mutex_lock(&dev_pm_qos_mtx);
-        dev->power.qos = NULL;
-        dev->power.power_state = PMSG_ON;
-        mutex_unlock(&dev_pm_qos_mtx);
-}
+static void __dev_pm_qos_hide_latency_limit(struct device *dev);
+static void __dev_pm_qos_hide_flags(struct device *dev);
 
 /**
  * dev_pm_qos_constraints_destroy
@@ -226,16 +216,15 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
         struct pm_qos_constraints *c;
         struct pm_qos_flags *f;
 
+        mutex_lock(&dev_pm_qos_mtx);
+
         /*
          * If the device's PM QoS resume latency limit or PM QoS flags have been
          * exposed to user space, they have to be hidden at this point.
          */
-        dev_pm_qos_hide_latency_limit(dev);
-        dev_pm_qos_hide_flags(dev);
+        __dev_pm_qos_hide_latency_limit(dev);
+        __dev_pm_qos_hide_flags(dev);
 
-        mutex_lock(&dev_pm_qos_mtx);
-
-        dev->power.power_state = PMSG_INVALID;