isci: Manage the LLHANG timer enable/disable per-device.

The LLHANG timer should be enabled once per device.  This patch corrects
both the timer enable and the timer disable for the remote device.

Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/scsi/isci/remote_device.c

@@ -1520,3 +1520,20 @@ enum sci_status isci_remote_device_reset_complete(
 	return status;
 }
 
+void isci_dev_set_hang_detection_timeout(
+	struct isci_remote_device *idev,
+	u32 timeout)
+{
+	if (dev_is_sata(idev->domain_dev)) {
+		if (timeout) {
+			if (test_and_set_bit(IDEV_RNC_LLHANG_ENABLED,
+					     &idev->flags))
+				return;  /* Already enabled. */
+		} else if (!test_and_clear_bit(IDEV_RNC_LLHANG_ENABLED,
+					       &idev->flags))
+			return;  /* Not enabled. */
+
+		sci_port_set_hang_detection_timeout(idev->owning_port,
+						    timeout);
+	}
+}

drivers/scsi/isci/remote_device.h

@@ -85,6 +85,7 @@ struct isci_remote_device {
 	#define IDEV_GONE 3
 	#define IDEV_IO_READY 4
 	#define IDEV_IO_NCQERROR 5
+	#define IDEV_RNC_LLHANG_ENABLED 6
 	unsigned long flags;
 	struct kref kref;
 	struct isci_port *isci_port;
@@ -308,12 +309,7 @@ static inline void sci_remote_device_decrement_request_count(struct isci_remote_
 		idev->started_request_count--;
 }
 
-static inline void isci_dev_set_hang_detection_timeout(
-	struct isci_remote_device *idev,
-	u32 timeout)
-{
-	sci_port_set_hang_detection_timeout(idev->owning_port, timeout);
-}
+void isci_dev_set_hang_detection_timeout(struct isci_remote_device *idev, u32 timeout);
 
 enum sci_status sci_remote_device_frame_handler(
 	struct isci_remote_device *idev,

drivers/scsi/isci/remote_node_context.c

@@ -615,8 +615,7 @@ enum sci_status sci_remote_node_context_suspend(
 	if ((suspend_reason == SCI_SW_SUSPEND_NORMAL) ||
 	    (suspend_reason == SCI_SW_SUSPEND_LINKHANG_DETECT)) {
 
-		if ((suspend_reason == SCI_SW_SUSPEND_LINKHANG_DETECT)
-		 && dev_is_sata(idev->domain_dev))
+		if (suspend_reason == SCI_SW_SUSPEND_LINKHANG_DETECT)
 			isci_dev_set_hang_detection_timeout(idev, 0x00000001);
 
 		sci_remote_device_post_request(