[PATCH] PCI: ACPI: Don't blindly trust `HotPlugSupportInD3`

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

The `_DSD` `HotPlugSupportInD3` is supposed to indicate the ability for a
bridge to be able to wakeup from D3.

This however is static information in the ACPI table at BIOS compilation
time and on some platforms it's possible to configure the firmware at boot
up such that `_S0W` will not return "0" indicating the inability to wake
up the system from D3.

To fix these situations explicitly check that the ACPI device claims the
system can be awoken in `acpi_pci_bridge_d3`.

Link: https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/07_Power_and_Performance_Mgmt/device-power-management-objects.html?highlight=s0w#s0w-s0-device-wake-state
Link: https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-pcie-root-ports-supporting-hot-plug-in-d3
Fixes: 26ad34d510a87 ("PCI / ACPI: Whitelist D3 for more PCIe hotplug ports")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/pci/pci-acpi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index a42dbf448860..9f8f55ed09d9 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -999,6 +999,9 @@ bool acpi_pci_bridge_d3(struct pci_dev *dev)
 	if (!adev)
 		return false;
 
+	if (!adev->wakeup.flags.valid)
+		return false;
+
 	if (acpi_dev_get_property(adev, "HotPlugSupportInD3",
 				   ACPI_TYPE_INTEGER, &obj) < 0)
 		return false;
-- 
2.34.1