ACPI / PM: Add state information to error message in acpi_device_set_power()

The state information can be useful to know what the problem is when
an error message about a device can not being set to a higher power
state than its parent appeared, so this patch adds such state
information for both the target state of the device and the current
state of its parent.

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

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index beb9625e8458d089faff6420cbbb209be753fcb2..59d3202f6b36fc197afe259b343764cb2a9621aa 100644 (file)
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -179,7 +179,9 @@ int acpi_device_set_power(struct acpi_device *device, int state)
        }
        if (device->parent && (state < device->parent->power.state)) {
                dev_warn(&device->dev,
-                        "Cannot transition to a higher-powered state than parent\n");
+                        "Cannot transition to power state %s for parent in %s\n",
+                        acpi_power_state_string(state),
+                        acpi_power_state_string(device->parent->power.state));
                return -ENODEV;
        }