[PATCH 1/1] ACPI: Support D3 COLD device for old BIOS

[Ken Xue <ken.xue@amd.com>]

D3cold is only regarded as valid if the "_PR3" object is present
for the given device after the commit <20dacb71ad28>
(ACPI/PM: Reworkdevice power management to follow ACPI 6).

But some old BIOS only defined "_PS3" for the D3COLD device.
And old kernel also believes the device has "_PS3" is a
D3COLD device.

So, add some logics for supporting D3 COLD device for old BIOS
which is compatible with earlier ACPI spec.

Signed-off-by: Ken Xue <Ken.Xue@amd.com>
Reported-and-tested-by: Gang Long <Gang.Long@amd.com>

---
 drivers/acpi/scan.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 01136b8..85c16bb 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -979,7 +979,9 @@ static void acpi_bus_get_power_flags(struct acpi_device *device)
 		acpi_bus_init_power_state(device, i);
 
 	INIT_LIST_HEAD(&device->power.states[ACPI_STATE_D3_COLD].resources);
-	if (!list_empty(&device->power.states[ACPI_STATE_D3_HOT].resources))
+	if (!list_empty(&device->power.states[ACPI_STATE_D3_HOT].resources) ||
+		((acpi_gbl_FADT.header.revision < 6) &&
+		device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set))
 		device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
 
 	/* Set defaults for D0 and D3hot states (always valid) */
-- 
1.9.1