[PATCH 2/8] libata: reimplement per-dev PM

[Tejun Heo <htejun@gmail.com>]

Reimplement per-dev PM.  The original implementation directly put the
device into suspended mode and didn't synchronize w/ EH operations
including hotplug.  This patch reimplements ata_scsi_device_suspend()
and ata_scsi_device_resume() such that they request EH to perform the
respective operations.  Both functions synchronize with hotplug such
that it doesn't affect already detached devices.

Suspend wait for completion but resume just issues request and
returns.  This allows parallel wake up of devices and thus speeds up
system resume.

Due to sdev detach synchronization, it's not feasible to separate out
EH requesting from sdev handling; thus, ata_device_suspend/resume()
are removed and everything is implemented in respective libata-scsi
functions.

Signed-off-by: Tejun Heo <htejun@gmail.com>

---

 drivers/scsi/libata-core.c |   84 ---------------------------------
 drivers/scsi/libata-scsi.c |  112 ++++++++++++++++++++++++++++++++++++++++++--
 include/linux/libata.h     |   11 ++--
 3 files changed, 111 insertions(+), 96 deletions(-)

73557f86d2c055c6350fe254cf7af49798d44dac
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 5d34df6..7e584c9 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -5003,88 +5003,6 @@ int ata_flush_cache(struct ata_device *d
 	return 0;
 }
 
-static int ata_standby_drive(struct ata_device *dev)
-{
-	unsigned int err_mask;
-
-	err_mask = ata_do_simple_cmd(dev, ATA_CMD_STANDBYNOW1);
-	if (err_mask) {
-		ata_dev_printk(dev, KERN_ERR, "failed to standby drive "
-			       "(err_mask=0x%x)\n", err_mask);
-		return -EIO;
-	}
-
-	return 0;
-}
-
-static int ata_start_drive(struct ata_device *dev)
-{
-	unsigned int err_mask;
-
-	err_mask = ata_do_simple_cmd(dev, ATA_CMD_IDLEIMMEDIATE);
-	if (err_mask) {
-		ata_dev_printk(dev, KERN_ERR, "failed to start drive "
-			       "(err_mask=0x%x)\n", err_mask);
-		return -EIO;
-	}
-
-	return 0;
-}
-
-/**
- *	ata_device_resume - wakeup a previously suspended devices
- *	@dev: the device to resume
- *
- *	Kick the drive back into action, by sending it an idle immediate
- *	command and making sure its transfer mode matches between drive
- *	and host.
- *
- */
-int ata_device_resume(struct ata_device *dev)
-{
-	struct ata_port *ap = dev->ap;
-
-	if (ap->flags & ATA_FLAG_SUSPENDED) {
-		struct ata_device *failed_dev;
-
-		ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
-		ata_busy_wait(ap, ATA_BUSY | ATA_DRQ, 200000);
-
-		ap->flags &= ~ATA_FLAG_SUSPENDED;
-		while (ata_set_mode(ap, &failed_dev))
-			ata_dev_disable(failed_dev);
-	}
-	if (!ata_dev_enabled(dev))
-		return 0;
-	if (dev->class == ATA_DEV_ATA)
-		ata_start_drive(dev);
-
-	return 0;
-}
-
-/**
- *	ata_device_suspend - prepare a device for suspend
- *	@dev: the device to suspend
- *	@state: target power management state
- *
- *	Flush the cache on the drive, if appropriate, then issue a
- *	standbynow command.
- */
-int ata_device_suspend(struct ata_device *dev, pm_message_t state)
-{
-	struct ata_port *ap = dev->ap;
-
-	if (!ata_dev_enabled(dev))
-		return 0;
-	if (dev->class == ATA_DEV_ATA)
-		ata_flush_cache(dev);
-
-	if (state.event != PM_EVENT_FREEZE)
-		ata_standby_drive(dev);
-	ap->flags |= ATA_FLAG_SUSPENDED;
-	return 0;
-}
-
 /**
  *	ata_port_start - Set port up for dma.
  *	@ap: Port to initialize
@@ -5938,8 +5856,6 @@ EXPORT_SYMBOL_GPL(ata_pci_default_filter
 EXPORT_SYMBOL_GPL(ata_pci_clear_simplex);
 #endif /* CONFIG_PCI */
 
-EXPORT_SYMBOL_GPL(ata_device_suspend);
-EXPORT_SYMBOL_GPL(ata_device_resume);
 EXPORT_SYMBOL_GPL(ata_scsi_device_suspend);
 EXPORT_SYMBOL_GPL(ata_scsi_device_resume);
 
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 93d18a7..67a719c 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -399,20 +399,120 @@ void ata_dump_status(unsigned id, struct
 	}
 }
 
-int ata_scsi_device_resume(struct scsi_device *sdev)
+/**
+ *	ata_scsi_device_suspend - suspend ATA device associated with sdev
+ *	@sdev: the SCSI device to suspend
+ *	@state: target power management state
+ *
+ *	Request suspend EH action on the ATA device associated with
+ *	@sdev and wait for the operation to complete.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+int ata_scsi_device_suspend(struct scsi_device *sdev, pm_message_t state)
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
-	struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);
+	struct ata_device *dev = ata_scsi_find_dev(ap, sdev);
+	unsigned long flags;
+	unsigned int action;
+	int rc = 0;
+
+	if (!dev)
+		goto out;
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	/* wait for the previous resume to complete */
+	while (dev->flags & ATA_DFLAG_SUSPENDED) {
+		spin_unlock_irqrestore(ap->lock, flags);
+		ata_port_wait_eh(ap);
+		spin_lock_irqsave(ap->lock, flags);
+	}
+
+	/* if @sdev is already detached, nothing to do */
+	if (sdev->sdev_state == SDEV_OFFLINE ||
+	    sdev->sdev_state == SDEV_CANCEL || sdev->sdev_state == SDEV_DEL)
+		goto out_unlock;
+
+	/* request suspend */
+	action = ATA_EH_SUSPEND;
+	if (state.event != PM_EVENT_SUSPEND)
+		action |= ATA_EH_PM_FREEZE;
+	ap->eh_info.dev_action[dev->devno] |= action;
+	ata_port_schedule_eh(ap);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	/* wait for EH to do the job */
+	ata_port_wait_eh(ap);
+
+	spin_lock_irqsave(ap->lock, flags);
 
-	return ata_device_resume(dev);
+	/* If @sdev is still attached but the associated ATA device
+	 * isn't suspended, the operation failed.
+	 */
+	if (sdev->sdev_state != SDEV_OFFLINE &&
+	    sdev->sdev_state != SDEV_CANCEL && sdev->sdev_state != SDEV_DEL &&
+	    !(dev->flags & ATA_DFLAG_SUSPENDED))
+		rc = -EIO;
+
+ out_unlock:
+	spin_unlock_irqrestore(ap->lock, flags);
+ out:
+	if (rc == 0)
+		sdev->sdev_gendev.power.power_state = state;
+	return rc;
 }
 
-int ata_scsi_device_suspend(struct scsi_device *sdev, pm_message_t state)
+/**
+ *	ata_scsi_device_resume - resume ATA device associated with sdev
+ *	@sdev: the SCSI device to resume
+ *
+ *	Request resume EH action on the ATA device associated with
+ *	@sdev and return immediately.  This enables parallel
+ *	wakeup/spinup of devices.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0.
+ */
+int ata_scsi_device_resume(struct scsi_device *sdev)
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
-	struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);
+	struct ata_device *dev = ata_scsi_find_dev(ap, sdev);
+	unsigned long flags;
+	unsigned int action;
+
+	if (!dev)
+		goto out;
 
-	return ata_device_suspend(dev, state);
+	spin_lock_irqsave(ap->lock, flags);
+
+	/* if @sdev is already detached, nothing to do */
+	if (sdev->sdev_state == SDEV_OFFLINE ||
+	    sdev->sdev_state == SDEV_CANCEL || sdev->sdev_state == SDEV_DEL)
+		goto out_unlock;
+
+	/* request resume */
+	action = ATA_EH_RESUME;
+	if (sdev->sdev_gendev.power.power_state.event == PM_EVENT_SUSPEND)
+		ata_ehi_hotplugged(&ap->eh_info);
+	else
+		action |= ATA_EH_PM_FREEZE;
+	ap->eh_info.dev_action[dev->devno] |= action;
+	ata_port_schedule_eh(ap);
+
+ out_unlock:
+	spin_unlock_irqrestore(ap->lock, flags);
+ out:
+	sdev->sdev_gendev.power.power_state = PMSG_ON;
+	return 0;
 }
 
 /**
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 78c1be0..33943e9 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -249,12 +249,13 @@ enum {
 	ATA_EH_REVALIDATE	= (1 << 0),
 	ATA_EH_SOFTRESET	= (1 << 1),
 	ATA_EH_HARDRESET	= (1 << 2),
-	ATA_EH_SUSPEND		= (1 << 3),
-	ATA_EH_RESUME		= (1 << 4),
+	ATA_EH_SUSPEND		= (1 << 4),
+	ATA_EH_RESUME		= (1 << 5),
+	ATA_EH_PM_FREEZE	= (1 << 6), /* freeze, not actual suspend */
 
 	ATA_EH_RESET_MASK	= ATA_EH_SOFTRESET | ATA_EH_HARDRESET,
-	ATA_EH_PERDEV_MASK	= ATA_EH_REVALIDATE |
-				  ATA_EH_SUSPEND | ATA_EH_RESUME,
+	ATA_EH_PERDEV_MASK	= ATA_EH_REVALIDATE | ATA_EH_SUSPEND |
+				  ATA_EH_RESUME | ATA_EH_PM_FREEZE,
 
 	/* ata_eh_info->flags */
 	ATA_EHI_HOTPLUGGED	= (1 << 0),  /* could have been hotplugged */
@@ -668,8 +669,6 @@ extern int ata_port_online(struct ata_po
 extern int ata_port_offline(struct ata_port *ap);
 extern int ata_scsi_device_resume(struct scsi_device *);
 extern int ata_scsi_device_suspend(struct scsi_device *, pm_message_t state);
-extern int ata_device_resume(struct ata_device *);
-extern int ata_device_suspend(struct ata_device *, pm_message_t state);
 extern int ata_ratelimit(void);
 extern unsigned int ata_busy_sleep(struct ata_port *ap,
 				   unsigned long timeout_pat,
-- 
1.3.2