On 07/31/2013 06:27 PM, Rafael J. Wysocki wrote:

quoted

Patch to add state information in error message, apply on top of this

quoted

one.

From: Aaron Lu <redacted>
Subject: [PATCH] ACPI / PM: Add state information in error message for
 acpi_device_set_power

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

Signed-off-by: Aaron Lu <redacted>
---
 drivers/acpi/device_pm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index beb9625..707258b 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c

@@ -179,7 +179,8 @@ 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 a higher-powered state %d than parent's state %d\n",

This message will look a little odd I think ->

quoted

quoted

+			 state, device->parent->power.state);

-> and please don't use raw numbers in such messages.

What about

	"Cannot transition to power state %s for parent in %s\n",
	acpi_power_state_string(state),
	acpi_power_state_string(device->parent->power.state)

Thanks for the suggestion, updated patch here:

From: Aaron Lu <redacted>
Subject: [PATCH] ACPI / PM: Add state information in error message for
 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 <redacted>
---
 drivers/acpi/device_pm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index beb9625..59d3202 100644
--- 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;
 	}
 

-- 
1.8.3.2.10.g43d11f4