ata: avoid probing NCQ Prio Support if not explicitly requested

Previously, when the ata device was being initialized we were
probing for NCQ prio support by checking the identify information
and also checking the log page that holds information about ncq prio
support.

This caused an error on an Intel HBA so the code is now updated to
only probe for NCQ prio support when the sysfs variable controlling
NCQ prio support is enabled.

tj: Update formatting, switch to spin_[un]lock_irq() and update
    locking a bit, use REVALIDATE instead of RESET, and return -EIO
    instead of -EINVAL on config failure.
Signed-off-by: Adam Manzanares <adam.manzanares@wdc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/libata-core.c

@@ -787,7 +787,7 @@ int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
 		if (tf->flags & ATA_TFLAG_FUA)
 			tf->device |= 1 << 7;
 
-		if (dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLE) {
+		if (dev->flags & ATA_DFLAG_NCQ_PRIO) {
 			if (class == IOPRIO_CLASS_RT)
 				tf->hob_nsect |= ATA_PRIO_HIGH <<
 						 ATA_SHIFT_PRIO;
@@ -2168,6 +2168,11 @@ static void ata_dev_config_ncq_prio(struct ata_device *dev)
 	struct ata_port *ap = dev->link->ap;
 	unsigned int err_mask;
 
+	if (!(dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLE)) {
+		dev->flags &= ~ATA_DFLAG_NCQ_PRIO;
+		return;
+	}
+
 	err_mask = ata_read_log_page(dev,
 				     ATA_LOG_SATA_ID_DEV_DATA,
 				     ATA_LOG_SATA_SETTINGS,
@@ -2180,10 +2185,12 @@ static void ata_dev_config_ncq_prio(struct ata_device *dev)
 		return;
 	}
 
-	if (ap->sector_buf[ATA_LOG_NCQ_PRIO_OFFSET] & BIT(3))
+	if (ap->sector_buf[ATA_LOG_NCQ_PRIO_OFFSET] & BIT(3)) {
 		dev->flags |= ATA_DFLAG_NCQ_PRIO;
-	else
+	} else {
+		dev->flags &= ~ATA_DFLAG_NCQ_PRIO;
 		ata_dev_dbg(dev, "SATA page does not support priority\n");
+	}
 
 }
 

drivers/ata/libata-scsi.c

@@ -272,7 +272,8 @@ DEVICE_ATTR(unload_heads, S_IRUGO | S_IWUSR,
 EXPORT_SYMBOL_GPL(dev_attr_unload_heads);
 
 static ssize_t ata_ncq_prio_enable_show(struct device *device,
-					struct device_attribute *attr, char *buf)
+					struct device_attribute *attr,
+					char *buf)
 {
 	struct scsi_device *sdev = to_scsi_device(device);
 	struct ata_port *ap;
@@ -305,7 +306,6 @@ static ssize_t ata_ncq_prio_enable_store(struct device *device,
 	struct ata_port *ap;
 	struct ata_device *dev;
 	long int input;
-	unsigned long flags;
 	int rc;
 
 	rc = kstrtol(buf, 10, &input);
@@ -315,28 +315,32 @@ static ssize_t ata_ncq_prio_enable_store(struct device *device,
 		return -EINVAL;
 
 	ap = ata_shost_to_port(sdev->host);
-
-	spin_lock_irqsave(ap->lock, flags);
 	dev = ata_scsi_find_dev(ap, sdev);
-	if (unlikely(!dev)) {
-		rc = -ENODEV;
-		goto unlock;
-	}
+	if (unlikely(!dev))
+		return  -ENODEV;
+
+	spin_lock_irq(ap->lock);
+	if (input)
+		dev->flags |= ATA_DFLAG_NCQ_PRIO_ENABLE;
+	else
+		dev->flags &= ~ATA_DFLAG_NCQ_PRIO_ENABLE;
+
+	dev->link->eh_info.action |= ATA_EH_REVALIDATE;
+	dev->link->eh_info.flags |= ATA_EHI_QUIET;
+	ata_port_schedule_eh(ap);
+	spin_unlock_irq(ap->lock);
+
+	ata_port_wait_eh(ap);
 
 	if (input) {
+		spin_lock_irq(ap->lock);
 		if (!(dev->flags & ATA_DFLAG_NCQ_PRIO)) {
-			rc = -EOPNOTSUPP;
-			goto unlock;
+			dev->flags &= ~ATA_DFLAG_NCQ_PRIO_ENABLE;
+			rc = -EIO;
 		}
-
-		dev->flags |= ATA_DFLAG_NCQ_PRIO_ENABLE;
-	} else {
-		dev->flags &= ~ATA_DFLAG_NCQ_PRIO_ENABLE;
+		spin_unlock_irq(ap->lock);
 	}
 
-unlock:
-	spin_unlock_irqrestore(ap->lock, flags);
-
 	return rc ? rc : len;
 }