--- linux-2.6.20-rc6nv/drivers/ata/sata_nv.c	2007-01-28 17:05:27.000000000 -0600
+++ linux-2.6.20-rc6nvedit/drivers/ata/sata_nv.c	2007-01-28 17:20:11.000000000 -0600
@@ -1172,16 +1172,31 @@ static void nv_adma_fill_sg(struct ata_q
 		cpb->next_aprd = cpu_to_le64(((u64)(pp->aprd_dma + NV_ADMA_SGTBL_SZ * qc->tag)));
 }
 
+static int nv_adma_use_reg_mode(struct ata_queued_cmd *qc)
+{
+	struct nv_adma_port_priv *pp = qc->ap->private_data;
+	
+	/* ADMA engine can only be used for non-ATAPI DMA commands,
+	   or interrupt-driven no-data commands. */
+	if((pp->flags & NV_ADMA_ATAPI_SETUP_COMPLETE) ||
+	   (qc->tf.flags & ATA_TFLAG_POLLING))
+		return 1;
+
+	if((qc->flags & ATA_QCFLAG_DMAMAP) ||
+	   (qc->tf.protocol == ATA_PROT_NODATA))
+		return 0;
+	
+	return 1;
+}
+
 static void nv_adma_qc_prep(struct ata_queued_cmd *qc)
 {
 	struct nv_adma_port_priv *pp = qc->ap->private_data;
 	struct nv_adma_cpb *cpb = &pp->cpb[qc->tag];
 	u8 ctl_flags = NV_CPB_CTL_CPB_VALID |
-		       NV_CPB_CTL_APRD_VALID |
 		       NV_CPB_CTL_IEN;
 
-	if (!(qc->flags & ATA_QCFLAG_DMAMAP) ||
-	     (pp->flags & NV_ADMA_ATAPI_SETUP_COMPLETE)) {
+	if (nv_adma_use_reg_mode(qc)) {
 		nv_adma_register_mode(qc->ap);
 		ata_qc_prep(qc);
 		return;
@@ -1200,8 +1215,12 @@ static void nv_adma_qc_prep(struct ata_q
 	VPRINTK("qc->flags = 0x%lx\n", qc->flags);
 
 	nv_adma_tf_to_cpb(&qc->tf, cpb->tf);
-
-	nv_adma_fill_sg(qc, cpb);
+	
+	if(qc->flags & ATA_QCFLAG_DMAMAP) {
+		nv_adma_fill_sg(qc, cpb);
+		ctl_flags |= NV_CPB_CTL_APRD_VALID;
+	} else
+		memset(&cpb->aprd[0], 0, sizeof(struct nv_adma_prd) * 5);
 
 	/* Be paranoid and don't let the device see NV_CPB_CTL_CPB_VALID until we are
 	   finished filling in all of the contents */
@@ -1216,10 +1235,9 @@ static unsigned int nv_adma_qc_issue(str
 
 	VPRINTK("ENTER\n");
 
-	if (!(qc->flags & ATA_QCFLAG_DMAMAP) ||
-	     (pp->flags & NV_ADMA_ATAPI_SETUP_COMPLETE)) {
+	if (nv_adma_use_reg_mode(qc)) {
 		/* use ATA register mode */
-		VPRINTK("no dmamap or ATAPI, using ATA register mode: 0x%lx\n", qc->flags);
+		VPRINTK("using ATA register mode: 0x%lx\n", qc->flags);
 		nv_adma_register_mode(qc->ap);
 		return ata_qc_issue_prot(qc);
 	} else