arch/arm/src/lc823450: Assign I2S IRQ handling to CPU0

Previous commit assumed that the caller is running on CPU0.
However, the caller sometimes runs at CPU1.  This patch will
assign the caller to CPU0 explicitly.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

arch/arm/src/lc823450/lc823450_i2s.c

@@ -51,6 +51,10 @@
 #include <nuttx/audio/audio.h>
 #include <nuttx/audio/i2s.h>
 
+#ifdef CONFIG_SMP
+#  include <nuttx/signal.h>
+#endif
+
 #include "up_arch.h"
 #include "lc823450_dma.h"
 #include "lc823450_i2s.h"
@@ -460,8 +464,32 @@ FAR struct i2s_dev_s *lc823450_i2sdev_initialize(void)
   nxsem_init(&_sem_txdma, 0, 0);
   nxsem_init(&_sem_buf_under, 0, 0);
 
+#ifdef CONFIG_SMP
+  cpu_set_t cpuset0;
+  cpu_set_t cpuset1;
+
+  CPU_ZERO(&cpuset1);
+  CPU_SET(0, &cpuset1);
+
+  /* Backup the current affinity */
+
+  sched_getaffinity(getpid(), sizeof(cpuset0), &cpuset0);
+
+  /* Set the new affinity which assigns to CPU0 */
+
+  sched_setaffinity(getpid(), sizeof(cpuset1), &cpuset1);
+  nxsig_usleep(10 * 1000);
+#endif
+
   irq_attach(LC823450_IRQ_AUDIOBUF0, _i2s_isr, NULL);
 
+#ifdef CONFIG_SMP
+  /* Restore the original affinity */
+
+  sched_setaffinity(getpid(), sizeof(cpuset0), &cpuset0);
+  nxsig_usleep(10 * 1000);
+#endif
+
   /* Enable IRQ for Audio Buffer */
 
   up_enable_irq(LC823450_IRQ_AUDIOBUF0);