sata_dwc_460ex: support hardreset

The hardreset operation is currently not supported. This causes
sometime the SATA driver does cause kernel crash because of
none-determined state.a This patch will fix the issue.

Signed-off-by: Thang Q. Nguyen <tqnguyen@apm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_dwc_460ex.c

@@ -1581,10 +1581,31 @@ static void sata_dwc_qc_prep(struct ata_queued_cmd *qc)
 
 static void sata_dwc_error_handler(struct ata_port *ap)
 {
-	ap->link.flags |= ATA_LFLAG_NO_HRST;
 	ata_sff_error_handler(ap);
 }
 
+int sata_dwc_hardreset(struct ata_link *link, unsigned int *class,
+			unsigned long deadline)
+{
+	struct sata_dwc_device *hsdev = HSDEV_FROM_AP(link->ap);
+	int ret;
+
+	ret = sata_sff_hardreset(link, class, deadline);
+
+	sata_dwc_enable_interrupts(hsdev);
+
+	/* Reconfigure the DMA control register */
+	out_le32(&hsdev->sata_dwc_regs->dmacr,
+		 SATA_DWC_DMACR_TXRXCH_CLEAR);
+
+	/* Reconfigure the DMA Burst Transaction Size register */
+	out_le32(&hsdev->sata_dwc_regs->dbtsr,
+		 SATA_DWC_DBTSR_MWR(AHB_DMA_BRST_DFLT) |
+		 SATA_DWC_DBTSR_MRD(AHB_DMA_BRST_DFLT));
+
+	return ret;
+}
+
 /*
  * scsi mid-layer and libata interface structures
  */
@@ -1604,6 +1625,7 @@ static struct ata_port_operations sata_dwc_ops = {
 	.inherits		= &ata_sff_port_ops,
 
 	.error_handler		= sata_dwc_error_handler,
+	.hardreset		= sata_dwc_hardreset,
 
 	.qc_prep		= sata_dwc_qc_prep,
 	.qc_issue		= sata_dwc_qc_issue,