diff --git a/arch/arm/src/lc823450/lc823450_cpupause.c b/arch/arm/src/lc823450/lc823450_cpupause.c
index a8f663e6d8..10b4a0baf2 100644
--- a/arch/arm/src/lc823450/lc823450_cpupause.c
+++ b/arch/arm/src/lc823450/lc823450_cpupause.c
@@ -185,9 +185,6 @@ int up_cpu_paused(int cpu)
 
   up_restorestate(tcb->xcp.regs);
 
-  /* FIXME */
-  up_udelay(500);
-
   spin_unlock(&g_cpu_wait[cpu]);
 
   return OK;
diff --git a/arch/arm/src/lc823450/lc823450_gpio.c b/arch/arm/src/lc823450/lc823450_gpio.c
index a9c6d06b50..dde194ac83 100644
--- a/arch/arm/src/lc823450/lc823450_gpio.c
+++ b/arch/arm/src/lc823450/lc823450_gpio.c
@@ -54,6 +54,10 @@
 #  include <nuttx/ioex.h>
 #endif
 
+#ifdef CONFIG_SMP
+#  include <nuttx/spinlock.h>
+#endif
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -75,6 +79,10 @@ static FAR struct ioex_dev_s *g_ioex_dev;
 static FAR struct vgpio_ops_s *vgpio_ops[GPIO_VIRTUAL_NUM];
 #endif /* CONFIG_LC823450_VGPIO */
 
+#ifdef CONFIG_SMP
+static volatile spinlock_t g_gpio_lock;
+#endif
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -400,24 +408,34 @@ void lc823450_gpio_write(uint16_t gpiocfg, bool value)
 
       regaddr = lc823450_get_gpio_data(port);
 
+#ifdef CONFIG_SMP
+      flags = up_irq_save();
+      spin_lock(&g_gpio_lock);
+#else
       flags = enter_critical_section();
+#endif
 
       /* Write the value (0 or 1).  To the data register */
 
       regval  = getreg32(regaddr);
 
-    if (value)
-      {
-        regval |= (1 << pin);
-      }
-    else
-      {
-        regval &= ~(1 << pin);
-      }
+      if (value)
+        {
+          regval |= (1 << pin);
+        }
+      else
+        {
+          regval &= ~(1 << pin);
+        }
 
-    putreg32(regval, regaddr);
+      putreg32(regval, regaddr);
 
-    leave_critical_section(flags);
+#ifdef CONFIG_SMP
+      spin_unlock(&g_gpio_lock);
+      up_irq_restore(flags);
+#else
+      leave_critical_section(flags);
+#endif
   }
 #ifdef CONFIG_IOEX
   else if (port <= (GPIO_PORTEX >> GPIO_PORT_SHIFT))
diff --git a/arch/arm/src/lc823450/lc823450_serial.c b/arch/arm/src/lc823450/lc823450_serial.c
index eba588f38b..5ddeb324df 100644
--- a/arch/arm/src/lc823450/lc823450_serial.c
+++ b/arch/arm/src/lc823450/lc823450_serial.c
@@ -1007,7 +1007,11 @@ static bool up_txready(struct uart_dev_s *dev)
     }
 #endif /* CONFIG_DEV_CONSOLE_SWITCH */
 
+#ifndef CONFIG_SMP
   return ((up_serialin(priv, UART_USR) & UART_USR_TXFULL) == 0);
+#else
+  return (UART_USFS_TXFF_LV(up_serialin(priv, UART_USFS)) <= 1);
+#endif
 }
 
 /****************************************************************************
diff --git a/configs/lc823450-xgevk/README.txt b/configs/lc823450-xgevk/README.txt
index bed898a495..6c4e95e6f5 100644
--- a/configs/lc823450-xgevk/README.txt
+++ b/configs/lc823450-xgevk/README.txt
@@ -200,10 +200,6 @@ To play WAV file on uSD card,
   nxplayer> play /mnt/sd1/sample.wav
   nxplayer> volume 50
 
-Currently nxplayer does not work in SMP mode.
-
-  up_assert: Assertion failed at file:chip/lc823450_cpupause.c line: 279 task: wm8776
-
 
 TODO
 ^^^^
diff --git a/configs/lc823450-xgevk/audio/defconfig b/configs/lc823450-xgevk/audio/defconfig
index fb2fb238e0..af21efe27e 100644
--- a/configs/lc823450-xgevk/audio/defconfig
+++ b/configs/lc823450-xgevk/audio/defconfig
@@ -1,23 +1,20 @@
-# CONFIG_AUDIO_FORMAT_MP3 is not set
-# CONFIG_NSH_ARGCAT is not set
-# CONFIG_NX_DISABLE_1BPP is not set
-# CONFIG_SPI_EXCHANGE is not set
 CONFIG_AQM_1248A=y
-CONFIG_ARCH_BOARD_LC823450_XGEVK=y
+CONFIG_ARCH="arm"
 CONFIG_ARCH_BOARD="lc823450-xgevk"
+CONFIG_ARCH_BOARD_LC823450_XGEVK=y
 CONFIG_ARCH_CHIP_LC823450=y
 CONFIG_ARCH_FLOAT_H=y
 CONFIG_ARCH_INTERRUPTSTACK=2048
 CONFIG_ARCH_STDARG_H=y
-CONFIG_ARCH="arm"
 CONFIG_AUDIO_BUFFER_NUMBYTES=1024
 CONFIG_AUDIO_EXCLUDE_BALANCE=y
 CONFIG_AUDIO_EXCLUDE_FFORWARD=y
 CONFIG_AUDIO_EXCLUDE_TONE=y
+# CONFIG_AUDIO_FORMAT_MP3 is not set
 CONFIG_AUDIO_WM8776=y
 CONFIG_AUDIO=y
-CONFIG_BOARD_LOOPSPERMSEC=12061
 CONFIG_BOARDCTL_RESET=y
+CONFIG_BOARD_LOOPSPERMSEC=12061
 CONFIG_BUILTIN=y
 CONFIG_C99_BOOL8=y
 CONFIG_CODECS_HASH_MD5=y
@@ -37,15 +34,16 @@ CONFIG_EXAMPLES_NXHELLO_BPP=1
 CONFIG_EXAMPLES_NXHELLO=y
 CONFIG_EXAMPLES_OSTEST=y
 CONFIG_EXAMPLES_PIPE=y
+CONFIG_EXAMPLES_SMP=y
 CONFIG_EXPERIMENTAL=y
 CONFIG_FAT_LCNAMES=y
 CONFIG_FAT_LFN=y
-CONFIG_FS_FAT=y
 CONFIG_FS_FATTIME=y
+CONFIG_FS_FAT=y
 CONFIG_FS_PROCFS=y
 CONFIG_I2C_RESET=y
-CONFIG_I2C=y
 CONFIG_I2CTOOL_MAXBUS=1
+CONFIG_I2C=y
 CONFIG_I2S=y
 CONFIG_INTELHEX_BINARY=y
 CONFIG_LC823450_I2C0=y
@@ -69,6 +67,7 @@ CONFIG_NETUTILS_CODECS=y
 CONFIG_NFILE_DESCRIPTORS=45
 CONFIG_NFILE_STREAMS=8
 CONFIG_NSH_ARCHINIT=y
+# CONFIG_NSH_ARGCAT is not set
 CONFIG_NSH_BUILTIN_APPS=y
 CONFIG_NSH_CMDOPT_DD_STATS=y
 CONFIG_NSH_DISABLE_BASENAME=y
@@ -88,9 +87,10 @@ CONFIG_NSH_LINELEN=128
 CONFIG_NSH_MAXARGUMENTS=10
 CONFIG_NSH_READLINE=y
 CONFIG_NX_BLOCKING=y
-CONFIG_NX=y
+# CONFIG_NX_DISABLE_1BPP is not set
 CONFIG_NXFONT_MONO5X8=y
 CONFIG_NXPLAYER_DEFAULT_MEDIADIR="/mnt/sd1"
+CONFIG_NX=y
 CONFIG_PIPES=y
 CONFIG_POSIX_SPAWN_PROXY_STACKSIZE=2048
 CONFIG_PREALLOC_MQ_MSGS=4
@@ -107,14 +107,15 @@ CONFIG_RTC=y
 CONFIG_SCHED_ATEXIT=y
 CONFIG_SCHED_CHILD_STATUS=y
 CONFIG_SCHED_HAVE_PARENT=y
-CONFIG_SCHED_HPWORK=y
-CONFIG_SCHED_HPWORKPRIORITY=192
 CONFIG_SCHED_ONEXIT_MAX=32
 CONFIG_SCHED_ONEXIT=y
 CONFIG_SCHED_STARTHOOK=y
 CONFIG_SCHED_WAITPID=y
 CONFIG_SDCLONE_DISABLE=y
 CONFIG_SERIAL_TERMIOS=y
+CONFIG_SMP_NCPUS=2
+CONFIG_SMP=y
+# CONFIG_SPI_EXCHANGE is not set
 CONFIG_SPI=y
 CONFIG_START_DAY=3
 CONFIG_START_MONTH=10