Merge branch 'for-4.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata

Pull libata fixes from Tejun Heo:
 "This is quite late but SCT Write Same support added during this cycle
  is broken subtly but seriously and it'd be best to disable it before
  v4.9 gets released.

  This contains two commits - one low impact sata_mv fix and the
  mentioned disabling of SCT Write Same"

* 'for-4.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  libata-scsi: disable SCT Write Same for the moment
  ata: sata_mv: check for errors when parsing nr-ports from dt
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index c4eb4ae..8e575fb 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1159,6 +1159,7 @@
 {
 	sdev->use_10_for_rw = 1;
 	sdev->use_10_for_ms = 1;
+	sdev->no_write_same = 1;
 
 	/* Schedule policy is determined by ->qc_defer() callback and
 	 * it needs to see every deferred qc.  Set dev_blocked to 1 to
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index efc48bf..823e938 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -4090,7 +4090,20 @@
 
 	/* allocate host */
 	if (pdev->dev.of_node) {
-		of_property_read_u32(pdev->dev.of_node, "nr-ports", &n_ports);
+		rc = of_property_read_u32(pdev->dev.of_node, "nr-ports",
+					   &n_ports);
+		if (rc) {
+			dev_err(&pdev->dev,
+				"error parsing nr-ports property: %d\n", rc);
+			return rc;
+		}
+
+		if (n_ports <= 0) {
+			dev_err(&pdev->dev, "nr-ports must be positive: %d\n",
+				n_ports);
+			return -EINVAL;
+		}
+
 		irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
 	} else {
 		mv_platform_data = dev_get_platdata(&pdev->dev);