[PATCH] nvme: Look for StorageD3Enable on the actual acpi device as well as root port

[Mario Limonciello]

The documentation around the StorageD3Enable property wasn't prescriptive
on which device in the hierarchy should contain it.

The existing logic was intended for usage on Intel-based systems where the
root port contained the StorageD3Enable property.

On AMD systems the StorageD3Enable property is directly on the device
itself.

Link: https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/power-management-for-storage-hardware-devices-intro
Suggested-by: Prike Liang <Prike.Liang at amd.com>
CC: Shyam-sundar S-k <Shyam-sundar.S-k at amd.com>
CC: Alexander Deucher <Alexander.Deucher at amd.com>
CC: Hans de Goede <hdegoede at redhat.com>
CC: "Rafael J. Wysocki" <rjw at rjwysocki.net>
Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
 drivers/nvme/host/pci.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index a29b170701fc..4b7dd0cecd01 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2842,6 +2842,19 @@ static bool nvme_acpi_storage_d3(struct pci_dev *dev)
 	 * must use D3 to support deep platform power savings during
 	 * suspend-to-idle.
 	 */
+
+	/* First check the device itself for this property */
+	adev = ACPI_COMPANION(&dev->dev);
+	if (adev) {
+		fwnode_property_read_u8(acpi_fwnode_handle(adev), "StorageD3Enable", &val);
+		if (val == 1)
+			return true;
+	}
+
+	/*
+	 * For Intel systems the property is defined in the PXSX device for South
+	 * complex ports and in the PEGP device for North complex ports.
+	 */
 	root = pcie_find_root_port(dev);
 	if (!root)
 		return false;
@@ -2850,10 +2863,6 @@ static bool nvme_acpi_storage_d3(struct pci_dev *dev)
 	if (!adev)
 		return false;
 
-	/*
-	 * The property is defined in the PXSX device for South complex ports
-	 * and in the PEGP device for North complex ports.
-	 */
 	status = acpi_get_handle(adev->handle, "PXSX", &handle);
 	if (ACPI_FAILURE(status)) {
 		status = acpi_get_handle(adev->handle, "PEGP", &handle);
-- 
2.25.1