ACPI / PM: Handle missing _PSC in acpi_bus_update_power()

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.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 164d609d7c9e..dd314ef9bff1 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -355,6 +355,9 @@ int acpi_bus_update_power(acpi_handle handle, int *state_p)
         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;