[PATCH 2/2] ata: libata-core: Revert "ata: libata-core: Fix ata_pci_shutdown_one()"

[Damien Le Moal <dlemoal@kernel.org>]

This reverts commit fd3a6837d8e18cb7be80dcca1283276290336a7a.

Several users have signaled issues with commit fd3a6837d8e1 ("ata:
libata-core: Fix ata_pci_shutdown_one()") which causes failure of the
system SoC to go to a low power state. The reason for this problem
is not well understood but given that this patch is harmless with the
improvements to ata_dev_power_set_standby(), restore it to allow system
lower power state transitions.

For regular system shutdown, ata_dev_power_set_standby() will be
executed twice: once the scsi device is removed and another when
ata_pci_shutdown_one() executes and EH completes unloading the devices.
Make the second call to ata_dev_power_set_standby() do nothing by using
ata_dev_power_is_active() and return if the device is already in
standby.

Fixes: fd3a6837d8e1 ("ata: libata-core: Fix ata_pci_shutdown_one()")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/ata/libata-core.c | 75 +++++++++++++++++++++++----------------
 1 file changed, 45 insertions(+), 30 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index d9f80f4f70f5..20a366942626 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2001,6 +2001,33 @@ bool ata_dev_power_init_tf(struct ata_device *dev, struct ata_taskfile *tf,
 	return true;
 }
 
+static bool ata_dev_power_is_active(struct ata_device *dev)
+{
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+
+	ata_tf_init(dev, &tf);
+	tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
+	tf.protocol = ATA_PROT_NODATA;
+	tf.command = ATA_CMD_CHK_POWER;
+
+	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
+	if (err_mask) {
+		ata_dev_err(dev, "Check power mode failed (err_mask=0x%x)\n",
+			    err_mask);
+		/*
+		 * Assume we are in standby mode so that we always force a
+		 * spinup in ata_dev_power_set_active().
+		 */
+		return false;
+	}
+
+	ata_dev_dbg(dev, "Power mode: 0x%02x\n", tf.nsect);
+
+	/* Active or idle */
+	return tf.nsect == 0xff;
+}
+
 /**
  *	ata_dev_power_set_standby - Set a device power mode to standby
  *	@dev: target device
@@ -2017,8 +2044,9 @@ void ata_dev_power_set_standby(struct ata_device *dev)
 	struct ata_taskfile tf;
 	unsigned int err_mask;
 
-	/* If the device is already sleeping, do nothing. */
-	if (dev->flags & ATA_DFLAG_SLEEPING)
+	/* If the device is already sleeping or in standby, do nothing. */
+	if ((dev->flags & ATA_DFLAG_SLEEPING) ||
+	    !ata_dev_power_is_active(dev))
 		return;
 
 	/*
@@ -2046,33 +2074,6 @@ void ata_dev_power_set_standby(struct ata_device *dev)
 			    err_mask);
 }
 
-static bool ata_dev_power_is_active(struct ata_device *dev)
-{
-	struct ata_taskfile tf;
-	unsigned int err_mask;
-
-	ata_tf_init(dev, &tf);
-	tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
-	tf.protocol = ATA_PROT_NODATA;
-	tf.command = ATA_CMD_CHK_POWER;
-
-	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
-	if (err_mask) {
-		ata_dev_err(dev, "Check power mode failed (err_mask=0x%x)\n",
-			    err_mask);
-		/*
-		 * Assume we are in standby mode so that we always force a
-		 * spinup in ata_dev_power_set_active().
-		 */
-		return false;
-	}
-
-	ata_dev_dbg(dev, "Power mode: 0x%02x\n", tf.nsect);
-
-	/* Active or idle */
-	return tf.nsect == 0xff;
-}
-
 /**
  *	ata_dev_power_set_active -  Set a device power mode to active
  *	@dev: target device
@@ -6184,10 +6185,24 @@ EXPORT_SYMBOL_GPL(ata_pci_remove_one);
 void ata_pci_shutdown_one(struct pci_dev *pdev)
 {
 	struct ata_host *host = pci_get_drvdata(pdev);
+	struct ata_port *ap;
+	unsigned long flags;
 	int i;
 
+	/* Tell EH to disable all devices */
 	for (i = 0; i < host->n_ports; i++) {
-		struct ata_port *ap = host->ports[i];
+		ap = host->ports[i];
+		spin_lock_irqsave(ap->lock, flags);
+		ap->pflags |= ATA_PFLAG_UNLOADING;
+		ata_port_schedule_eh(ap);
+		spin_unlock_irqrestore(ap->lock, flags);
+	}
+
+	for (i = 0; i < host->n_ports; i++) {
+		ap = host->ports[i];
+
+		/* Wait for EH to complete before freezing the port */
+		ata_port_wait_eh(ap);
 
 		ap->pflags |= ATA_PFLAG_FROZEN;
 
-- 
2.43.0