--- pio1/drivers/scsi/libata-core.c	2005-09-02 18:37:26.000000000 +0800
+++ pio2/drivers/scsi/libata-core.c	2005-09-02 18:37:19.000000000 +0800
@@ -2893,21 +2893,20 @@
 {
 	struct ata_port *ap = _data;
 	unsigned long timeout = 0;
+	int has_next = 0;
 
 	switch (ap->pio_task_state) {
-	case PIO_ST_IDLE:
-		return;
-
 	case PIO_ST:
-		ata_pio_block(ap);
+		has_next = ata_pio_block(ap);
 		break;
 
 	case PIO_ST_LAST:
-		ata_pio_complete(ap);
+		has_next = ata_pio_complete(ap);
 		break;
 
 	case PIO_ST_POLL:
 	case PIO_ST_LAST_POLL:
+		has_next = 1;
 		timeout = ata_pio_poll(ap);
 		break;
 
@@ -2915,13 +2914,18 @@
 	case PIO_ST_ERR:
 		ata_pio_error(ap);
 		return;
+	default:
+		printk(KERN_ERR "ata%u unknown PIO task state %u\n", 
+		       ap->id, ap->pio_task_state);
+		return;
 	}
 
-	if (timeout)
-		queue_delayed_work(ata_wq, &ap->pio_task,
-				   timeout);
-	else
-		queue_work(ata_wq, &ap->pio_task);
+	if (has_next) {
+		if (timeout)
+			queue_delayed_work(ata_wq, &ap->pio_task, timeout);
+		else
+			queue_work(ata_wq, &ap->pio_task);
+	}
 }
 
 static void atapi_request_sense(struct ata_port *ap, struct ata_device *dev,