From 4b65c894f640faf51b67bbc771c520494f82d3af Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Thu, 28 Aug 2014 07:38:05 -0600
Subject: [PATCH] Z80: Move address environment switch from the task switchers
 to the interrupt handler.  That may save doing the action multiple times per
 interrupt

---
 arch/z80/src/common/up_blocktask.c   | 13 ++------
 arch/z80/src/common/up_doirq.c       | 48 +++++++++++++++++++++-------
 arch/z80/src/common/up_unblocktask.c | 13 ++------
 3 files changed, 41 insertions(+), 33 deletions(-)

diff --git a/arch/z80/src/common/up_blocktask.c b/arch/z80/src/common/up_blocktask.c
index d8bed13188..1527e06989 100644
--- a/arch/z80/src/common/up_blocktask.c
+++ b/arch/z80/src/common/up_blocktask.c
@@ -142,20 +142,11 @@ void up_block_task(FAR struct tcb_s *tcb, tstate_t task_state)
           /* dbg("New Active Task TCB=%p\n", rtcb); */
 
           /* Then setup so that the context will be performed on exit
-           * from the interrupt.
+           * from the interrupt.  Any necessary address environment
+           * changes will be made when the interrupt returns.
            */
 
           SET_IRQCONTEXT(rtcb);
-
-#ifdef CONFIG_ARCH_ADDRENV
-         /* Make sure that the address environment for the previously
-          * running task is closed down gracefully (data caches dump,
-          * MMU flushed) and set up the address environment for the new
-          * thread at the head of the ready-to-run list.
-          */
-
-         (void)group_addrenv(rtcb);
-#endif
         }
 
       /* Copy the user C context into the TCB at the (old) head of the
diff --git a/arch/z80/src/common/up_doirq.c b/arch/z80/src/common/up_doirq.c
index a92d3d7744..ab974c88a1 100644
--- a/arch/z80/src/common/up_doirq.c
+++ b/arch/z80/src/common/up_doirq.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/z80/src/common/up_doirq.c
  *
- *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -49,8 +49,10 @@
 #include "chip/switch.h"
 #include "up_internal.h"
 
+#include "group/group.h"
+
 /****************************************************************************
- * Definitions
+ * Pre-processor Definitions
  ****************************************************************************/
 
 /****************************************************************************
@@ -81,25 +83,49 @@ FAR chipreg_t *up_doirq(uint8_t irq, FAR chipreg_t *regs)
   return NULL; /* Won't get here */
 
 #else
+#ifdef CONFIG_ARCH_ADDRENV
+  FAR chipreg_t *newregs;
+#endif
+
   if (irq < NR_IRQS)
     {
-       DECL_SAVESTATE();
+      DECL_SAVESTATE();
 
-       /* Indicate that we have entered IRQ processing logic */
+      /* Indicate that we have entered IRQ processing logic */
 
-       IRQ_ENTER(irq, regs);
+      IRQ_ENTER(irq, regs);
 
-       /* Deliver the IRQ */
+      /* Deliver the IRQ */
 
-       irq_dispatch(irq, regs);
+      irq_dispatch(irq, regs);
 
-       /* If a context switch occurred, 'regs' will hold the new context */
+#ifdef CONFIG_ARCH_ADDRENV
+      /* If a context switch occurred, 'newregs' will hold the new context */
 
-       regs = IRQ_STATE();
+      newregs = IRQ_STATE();
 
-       /* Indicate that we are no longer in interrupt processing logic */
+      if (newregs != regs)
+        {
+          /* Make sure that the address environment for the previously
+           * running task is closed down gracefully and set up the
+           * address environment for the new thread at the head of the
+           * ready-to-run list.
+           */
 
-       IRQ_LEAVE(irq);
+          (void)group_addrenv(rtcb);
+        }
+
+      regs = newregs;
+
+#else
+      /* If a context switch occurred, 'regs' will hold the new context */
+
+      regs = IRQ_STATE();
+#endif
+
+      /* Indicate that we are no longer in interrupt processing logic */
+
+      IRQ_LEAVE(irq);
     }
 
   board_led_off(LED_INIRQ);
diff --git a/arch/z80/src/common/up_unblocktask.c b/arch/z80/src/common/up_unblocktask.c
index 257b19c6fc..12dcc4d51f 100644
--- a/arch/z80/src/common/up_unblocktask.c
+++ b/arch/z80/src/common/up_unblocktask.c
@@ -133,20 +133,11 @@ void up_unblock_task(FAR struct tcb_s *tcb)
           rtcb = (FAR struct tcb_s*)g_readytorun.head;
 
           /* Then setup so that the context will be performed on exit
-           * from the interrupt.
+           * from the interrupt.  Any necessary address environment
+           * changes will be made when the interrupt returns.
            */
 
           SET_IRQCONTEXT(rtcb);
-
-#ifdef CONFIG_ARCH_ADDRENV
-         /* Make sure that the address environment for the previously
-          * running task is closed down gracefully (data caches dump,
-          * MMU flushed) and set up the address environment for the new
-          * thread at the head of the ready-to-run list.
-          */
-
-         (void)group_addrenv(rtcb);
-#endif
         }
 
       /* We are not in an interrupt handler.  Copy the user C context