sata_promise: use TF interface for polling NODATA commands

sata_promise uses two different command modes - packet and TF.  Packet mode
is intelligent low-overhead mode while TF is the same old taskfile
interface.  As with other advanced interface (ahci/sil24),
ATA_TFLAG_POLLING has no effect in packet mode.  However, PIO commands are
issued using TF interface in polling mode, so pdc_interrupt() considers
interrupts spurious if ATA_TFLAG_POLLING is set.

This is broken for polling NODATA commands because command is issued using
packet mode but the interrupt handler ignores it due to ATA_TFLAG_POLLING.
Fix pdc_qc_issue_prot() such that ATA/ATAPI NODATA commands are issued
using TF interface if ATA_TFLAG_POLLING is set.

This patch fixes detection failure introduced by polling SETXFERMODE.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/ata/sata_promise.c

@@ -784,9 +784,12 @@ static unsigned int pdc_qc_issue_prot(struct ata_queued_cmd *qc)
 		if (qc->dev->flags & ATA_DFLAG_CDB_INTR)
 			break;
 		/*FALLTHROUGH*/
+	case ATA_PROT_NODATA:
+		if (qc->tf.flags & ATA_TFLAG_POLLING)
+			break;
+		/*FALLTHROUGH*/
 	case ATA_PROT_ATAPI_DMA:
 	case ATA_PROT_DMA:
-	case ATA_PROT_NODATA:
 		pdc_packet_start(qc);
 		return 0;
 
@@ -800,7 +803,7 @@ static unsigned int pdc_qc_issue_prot(struct ata_queued_cmd *qc)
 static void pdc_tf_load_mmio(struct ata_port *ap, const struct ata_taskfile *tf)
 {
 	WARN_ON (tf->protocol == ATA_PROT_DMA ||
-		 tf->protocol == ATA_PROT_NODATA);
+		 tf->protocol == ATA_PROT_ATAPI_DMA);
 	ata_tf_load(ap, tf);
 }
 
@@ -808,7 +811,7 @@ static void pdc_tf_load_mmio(struct ata_port *ap, const struct ata_taskfile *tf)
 static void pdc_exec_command_mmio(struct ata_port *ap, const struct ata_taskfile *tf)
 {
 	WARN_ON (tf->protocol == ATA_PROT_DMA ||
-		 tf->protocol == ATA_PROT_NODATA);
+		 tf->protocol == ATA_PROT_ATAPI_DMA);
 	ata_exec_command(ap, tf);
 }