Merge branch 'acpi-pm' into linux-next

* acpi-pm:
  ACPI / PM: Fix potential problem in acpi_device_get_power()

1 files changed, 24 insertions, 15 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index dd314ef9bff1..96de787e6104 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -145,27 +145,36 @@ int acpi_device_get_power(struct acpi_device *device, int *state)
         }
 
         /*
-         * Get the device's power state either directly (via _PSC) or
-         * indirectly (via power resources).
+         * Get the device's power state from power resources settings and _PSC,
+         * if available.
          */
+        if (device->power.flags.power_resources) {
+                int error = acpi_power_get_inferred_state(device, &result);
+                if (error)
+                        return error;
+        }
         if (device->power.flags.explicit_get) {
+                acpi_handle handle = device->handle;
                 unsigned long long psc;
-                acpi_status status = acpi_evaluate_integer(device->handle,
-                                                           "_PSC", NULL, &psc);
+                acpi_status status;
+
+                status = acpi_evaluate_integer(handle, "_PSC", NULL, &psc);
                 if (ACPI_FAILURE(status))
                         return -ENODEV;
 
-                result = psc;
-        }
-        /* The test below covers ACPI_STATE_UNKNOWN too. */
-        if (result <= ACPI_STATE_D2) {
-          ; /* Do nothing. */
-        } else if (device->power.flags.power_resources) {
-                int error = acpi_power_get_inferred_state(device, &result);
-                if (error)
-                        return error;
-        } else if (result == ACPI_STATE_D3_HOT) {
-                result = ACPI_STATE_D3;
+                /*
+                 * The power resources settings may indicate a power state
+                 * shallower than the actual power state of the device.
+                 *
+                 * Moreover, on systems predating ACPI 4.0, if the device
+                 * doesn't depend on any power resources and _PSC returns 3,
+                 * that means "power off".  We need to maintain compatibility
+                 * with those systems.
+                 */
+                if (psc > result && psc < ACPI_STATE_D3_COLD)
+                        result = psc;
+                else if (result == ACPI_STATE_UNKNOWN)
+                        result = psc > ACPI_STATE_D2 ? ACPI_STATE_D3_COLD : psc;
         }
 
         /*