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;
 	}
 
 	/*