--- old/drivers/scsi/sata_qstor.c	2006-11-14 11:30:37.000000000 -0500
+++ linux/drivers/scsi/sata_qstor.c	2006-11-14 13:22:05.000000000 -0500
@@ -299,6 +299,19 @@
 	return nelem;
 }
 
+static void qs_set_nien (struct ata_port *ap, int new_nien)
+{
+	struct ata_ioports *ioaddr = &ap->ioaddr;
+
+	if ((ap->ctl & ATA_NIEN) != new_nien) {
+		ap->ctl = (ap->ctl & ~ATA_NIEN) | new_nien;
+		ap->last_ctl = ap->ctl;
+		writeb(ap->ctl, (void __iomem *)ioaddr->ctl_addr);
+		wmb();
+		ata_check_status(ap);
+	}
+}
+
 static void qs_qc_prep(struct ata_queued_cmd *qc)
 {
 	struct qs_port_priv *pp = qc->ap->private_data;
@@ -357,6 +370,8 @@
 
 	switch (qc->tf.protocol) {
 	case ATA_PROT_DMA:
+		/* packet mode requires that the NIEN bit be turned on */
+		qs_set_nien(qc->ap, ATA_NIEN);
 
 		pp->state = qs_state_pkt;
 		qs_packet_start(qc);
@@ -370,6 +385,7 @@
 		break;
 	}
 
+	qs_set_nien(qc->ap, 0); // FIXME: is this necessary here?
 	pp->state = qs_state_mmio;
 	return ata_qc_issue_prot(qc);
 }