diff --git a/drivers/scsi/atp870u.c b/drivers/scsi/atp870u.c
index c4a59cc0821b..04b29d3e65d6 100644
--- a/drivers/scsi/atp870u.c
+++ b/drivers/scsi/atp870u.c
@@ -364,9 +364,9 @@ static irqreturn_t atp870u_intr_handle(int irq, void *dev_id)
 					atp_writeb_base(dev, 0x3b, atp_readb_base(dev, 0x3b) & 0x3f);
 			} else {				
 				if ((workreq->cmnd[0] == 0x08) || (workreq->cmnd[0] == 0x28) || (workreq->cmnd[0] == 0x0a) || (workreq->cmnd[0] == 0x2a))
-					atp_writeb_io(dev, c, 0x3a, (atp_readb_io(dev, c, 0x3a) & 0xf3) | 0x08);
+					atp_writeb_base(dev, 0x3a, (atp_readb_base(dev, 0x3a) & 0xf3) | 0x08);
 				else
-					atp_writeb_io(dev, c, 0x3a, atp_readb_io(dev, c, 0x3a) & 0xf3);
+					atp_writeb_base(dev, 0x3a, atp_readb_base(dev, 0x3a) & 0xf3);
 			}	
 			j = 0;
 			id = 1;
@@ -889,9 +889,9 @@ static void send_s870(struct atp_unit *dev,unsigned char c)
 			atp_writeb_base(dev, 0x3b, atp_readb_base(dev, 0x3b) & 0x3f);
 	} else {		
 		if ((workreq->cmnd[0] == 0x08) || (workreq->cmnd[0] == 0x28) || (workreq->cmnd[0] == 0x0a) || (workreq->cmnd[0] == 0x2a))
-			atp_writeb_io(dev, c, 0x3a, (atp_readb_io(dev, c, 0x3a) & 0xf3) | 0x08);
+			atp_writeb_base(dev, 0x3a, (atp_readb_base(dev, 0x3a) & 0xf3) | 0x08);
 		else
-			atp_writeb_io(dev, c, 0x3a, atp_readb_io(dev, c, 0x3a) & 0xf3);
+			atp_writeb_base(dev, 0x3a, atp_readb_base(dev, 0x3a) & 0xf3);
 	}	
 
 	if(workreq->sc_data_direction == DMA_TO_DEVICE) {