From 7f4064e511d5986116755523daddc23a56580559 Mon Sep 17 00:00:00 2001
From: zhuguangqing <zhuguangqing@pinecone.net>
Date: Mon, 27 Aug 2018 13:22:11 -0600
Subject: [PATCH] drivers/pm: PM: Decrease the power state in the reverse
 order.  Since the child driver need power off before parent driver.

---
 drivers/power/pm.h             |  4 +-
 drivers/power/pm_changestate.c | 82 +++++++++++++++++++++++++---------
 drivers/power/pm_initialize.c  |  2 +-
 drivers/power/pm_register.c    |  2 +-
 drivers/power/pm_unregister.c  |  2 +-
 include/nuttx/power/pm.h       |  2 +-
 6 files changed, 68 insertions(+), 26 deletions(-)

diff --git a/drivers/power/pm.h b/drivers/power/pm.h
index 6d11946b47..ec718ea53c 100644
--- a/drivers/power/pm.h
+++ b/drivers/power/pm.h
@@ -154,12 +154,12 @@ struct pm_global_s
 
   sem_t regsem;
 
-  /* registry is a singly-linked list of registered power management
+  /* registry is a doubly-linked list of registered power management
    * callback structures.  To ensure mutually exclusive access, this list
    * must be locked by calling pm_lock() before it is accessed.
    */
 
-  sq_queue_t registry;
+  dq_queue_t registry;
 };
 
 /****************************************************************************
diff --git a/drivers/power/pm_changestate.c b/drivers/power/pm_changestate.c
index 28280958d0..953c2fac24 100644
--- a/drivers/power/pm_changestate.c
+++ b/drivers/power/pm_changestate.c
@@ -76,23 +76,45 @@
 
 static int pm_prepall(int domain, enum pm_state_e newstate)
 {
-  FAR sq_entry_t *entry;
+  FAR dq_entry_t *entry;
   int ret = OK;
 
-  /* Visit each registered callback structure. */
-
-  for (entry = sq_peek(&g_pmglobals.registry);
-       entry && ret == OK;
-       entry = sq_next(entry))
+  if (newstate <= g_pmglobals.domain[domain].state)
     {
-      /* Is the prepare callback supported? */
+      /* Visit each registered callback structure in normal order. */
 
-      FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
-      if (cb->prepare)
+      for (entry = dq_peek(&g_pmglobals.registry);
+           entry && ret == OK;
+           entry = dq_next(entry))
         {
-          /* Yes.. prepare the driver */
+          /* Is the prepare callback supported? */
 
-          ret = cb->prepare(cb, domain, newstate);
+          FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
+          if (cb->prepare)
+            {
+              /* Yes.. prepare the driver */
+
+              ret = cb->prepare(cb, domain, newstate);
+            }
+        }
+    }
+  else
+    {
+      /* Visit each registered callback structure in reverse order. */
+
+      for (entry = dq_tail(&g_pmglobals.registry);
+           entry && ret == OK;
+           entry = dq_prev(entry))
+        {
+          /* Is the prepare callback supported? */
+
+          FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
+          if (cb->prepare)
+            {
+              /* Yes.. prepare the driver */
+
+              ret = cb->prepare(cb, domain, newstate);
+            }
         }
     }
 
@@ -120,20 +142,40 @@ static int pm_prepall(int domain, enum pm_state_e newstate)
 
 static inline void pm_changeall(int domain, enum pm_state_e newstate)
 {
-  FAR sq_entry_t *entry;
+  FAR dq_entry_t *entry;
 
-  /* Visit each registered callback structure. */
-
-  for (entry = sq_peek(&g_pmglobals.registry); entry; entry = sq_next(entry))
+if (newstate <= g_pmglobals.domain[domain].state)
     {
-      /* Is the notification callback supported? */
+      /* Visit each registered callback structure in normal order. */
 
-      FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
-      if (cb->notify)
+      for (entry = dq_peek(&g_pmglobals.registry); entry; entry = dq_next(entry))
         {
-          /* Yes.. notify the driver */
+          /* Is the notification callback supported? */
 
-          cb->notify(cb, domain, newstate);
+          FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
+          if (cb->notify)
+            {
+              /* Yes.. notify the driver */
+
+              cb->notify(cb, domain, newstate);
+            }
+        }
+    }
+  else
+    {
+      /* Visit each registered callback structure in reverse order. */
+
+    for (entry = dq_tail(&g_pmglobals.registry); entry; entry = dq_prev(entry))
+        {
+          /* Is the notification callback supported? */
+
+          FAR struct pm_callback_s *cb = (FAR struct pm_callback_s *)entry;
+          if (cb->notify)
+            {
+              /* Yes.. notify the driver */
+
+              cb->notify(cb, domain, newstate);
+            }
         }
     }
 }
diff --git a/drivers/power/pm_initialize.c b/drivers/power/pm_initialize.c
index 44b7065515..968ae64246 100644
--- a/drivers/power/pm_initialize.c
+++ b/drivers/power/pm_initialize.c
@@ -86,7 +86,7 @@ void pm_initialize(void)
    * data structure here.
    */
 
-  sq_init(&g_pmglobals.registry);
+  dq_init(&g_pmglobals.registry);
   nxsem_init(&g_pmglobals.regsem, 0, 1);
 }
 
diff --git a/drivers/power/pm_register.c b/drivers/power/pm_register.c
index 4f200ff572..bebc739dc0 100644
--- a/drivers/power/pm_register.c
+++ b/drivers/power/pm_register.c
@@ -79,7 +79,7 @@ int pm_register(FAR struct pm_callback_s *callbacks)
   ret = pm_lock();
   if (ret == OK)
     {
-      sq_addlast(&callbacks->entry, &g_pmglobals.registry);
+      dq_addlast(&callbacks->entry, &g_pmglobals.registry);
       pm_unlock();
     }
 
diff --git a/drivers/power/pm_unregister.c b/drivers/power/pm_unregister.c
index 7b3d376e2f..63a8e86a33 100644
--- a/drivers/power/pm_unregister.c
+++ b/drivers/power/pm_unregister.c
@@ -79,7 +79,7 @@ int pm_unregister(FAR struct pm_callback_s *callbacks)
   ret = pm_lock();
   if (ret == OK)
     {
-      sq_rem(&callbacks->entry, &g_pmglobals.registry);
+      dq_rem(&callbacks->entry, &g_pmglobals.registry);
       pm_unlock();
     }
 
diff --git a/include/nuttx/power/pm.h b/include/nuttx/power/pm.h
index 09daee2533..4a0e3a02a4 100644
--- a/include/nuttx/power/pm.h
+++ b/include/nuttx/power/pm.h
@@ -277,7 +277,7 @@ enum pm_state_e
 
 struct pm_callback_s
 {
-  struct sq_entry_s entry;   /* Supports a singly linked list */
+  struct dq_entry_s entry;   /* Supports a doubly linked list */
 
   /**************************************************************************
    * Name: prepare