[PATCH 2/2] ata: Adjust behavior when StorageD3Enable _DSD is set

[Mario Limonciello <mario.limonciello@amd.com>]

The StorageD3Enable _DSD is used for the vendor to indicate that the disk
should be opted into or out of a different behavior based upon the platform
design.

For AMD's Renoir and Green Sardine platforms it's important that any
attached SATA storage has transitioned into DevSlp when s2idle is used.

If the disk is left in active/partial/slumber, then the system is not able
to resume properly.

When the StorageD3Enable _DSD is detected, check the system is using s2idle
and DevSlp is enabled and if so explicitly wait long enough for the disk to
enter DevSlp.

Cc: Nehal-bakulchandra Shah <Nehal-bakulchandra.Shah@amd.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=214091
Link: https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/power-management-for-storage-hardware-devices-intro
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/ata/libahci.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 28430c093a7f..15c293da30ca 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -2322,6 +2322,18 @@ int ahci_port_resume(struct ata_port *ap)
 }
 EXPORT_SYMBOL_GPL(ahci_port_resume);
 
+static void ahci_handle_s2idle(struct ata_port *ap)
+{
+	void __iomem *port_mmio = ahci_port_base(ap);
+	u32 devslp;
+
+	if (pm_suspend_via_firmware())
+		return;
+	devslp = readl(port_mmio + PORT_DEVSLP);
+	if ((devslp & PORT_DEVSLP_ADSE))
+		ata_msleep(ap, devslp_idle_timeout);
+}
+
 #ifdef CONFIG_PM
 static int ahci_port_suspend(struct ata_port *ap, pm_message_t mesg)
 {
@@ -2336,6 +2348,9 @@ static int ahci_port_suspend(struct ata_port *ap, pm_message_t mesg)
 		ata_port_freeze(ap);
 	}
 
+	if (acpi_storage_d3(ap->host->dev))
+		ahci_handle_s2idle(ap);
+
 	ahci_rpm_put_port(ap);
 	return rc;
 }
-- 
2.25.1