[PATCH] libata irq-pio: misc fixes

   - ata_pio_block(): add ata_altstatus(ap) to prevent reading device status before it is valid
   - remove the unnecessary HSM_ST_IDLE state from ata_pio_task()
   - raise BUG() when unknown state is found in ata_pio_task()

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>

============
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/scsi/libata-core.c

@@ -3317,6 +3317,8 @@ static void ata_pio_block(struct ata_port *ap)
 
 		ata_pio_sector(qc);
 	}
+
+	ata_altstatus(ap); /* flush */
 }
 
 static void ata_pio_error(struct ata_port *ap)
@@ -3344,9 +3346,6 @@ static void ata_pio_task(void *_data)
 	qc_completed = 0;
 
 	switch (ap->hsm_task_state) {
-	case HSM_ST_IDLE:
-		return;
-
 	case HSM_ST:
 		ata_pio_block(ap);
 		break;
@@ -3364,6 +3363,10 @@ static void ata_pio_task(void *_data)
 	case HSM_ST_ERR:
 		ata_pio_error(ap);
 		return;
+
+	default:
+		BUG();
+		return;
 	}
 
 	if (timeout)