[PATCH] ACPI / PM: Handle missing _PSC in acpi_bus_update_power()

["Rafael J. Wysocki" <rjw@sisk.pl>]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

If _PS0 is defined for an ACPI device node, but _PSC isn't and
the device node doesn't use power resources for power management,
acpi_bus_update_power() will fail to update the power state of it,
because acpi_device_get_power() returns ACPI_STATE_UNKNOWN in that
case.

To handle that situation make acpi_bus_update_power() follow
acpi_bus_init_power() and try to force the given device node into
power state D0 if its actual power state cannot be determined.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

On top of linux-pm.git/bleeding-edge.

Thanks,
Rafael

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

Index: linux-pm/drivers/acpi/device_pm.c
===================================================================
--- linux-pm.orig/drivers/acpi/device_pm.c
+++ linux-pm/drivers/acpi/device_pm.c
@@ -355,6 +355,9 @@ int acpi_bus_update_power(acpi_handle ha
 	if (result)
 		return result;
 
+	if (state == ACPI_STATE_UNKNOWN)
+		state = ACPI_STATE_D0;
+
 	result = acpi_device_set_power(device, state);
 	if (!result && state_p)
 		*state_p = state;