Re: [PATCH 1/3] ACPI / PM: Only set power states of devices thatare power manageable

From: Aaron Lu
Date: Wed Jul 31 2013 - 02:48:32 EST

On 07/30/2013 10:04 PM, Rafael J. Wysocki wrote:
> On Tuesday, July 30, 2013 07:43:48 AM Aaron Lu wrote:
>> On 07/30/2013 06:21 AM, Rafael J. Wysocki wrote:
>>> On Monday, July 29, 2013 10:09:53 PM Aaron Lu wrote:
>>>> On 07/27/2013 09:10 PM, Rafael J. Wysocki wrote:
>>>>> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>>>>> Make acpi_device_set_power() check if the given device is power
>>>>> manageable before checking if the given power state is valid for that
>>>>> device. Otherwise it will print that "Device does not support" that
>>>>> power state into the kernel log, which may not make sense for some
>>>>> power states (D0 and D3cold are supported by all devices by
>>>>> definition).
>>>> It will not print "Device does not support" that power state if that
>>>> power state is D0 or D3cold since we have unconditionally set those two
>>>> power state's valid flag.
>>> So you didn't actually looked at acpi_bus_get_power_flags() that set the
>>> power.states[].flags.valid flag, because If you had looked at it, you would
>>> have seen that that's not the case.
>>> No, we don't set the valid flag for devices that aren't power manageable
>>> (i.e. have flags.power_manageable unset), which is the *whole* *point* of
>>> this change.
>> Right, I missed this. Sorry for the noise.
>>>> OTOH, what value should we return for a device node that is not power
>>>> manageable in acpi_device_set_power when the target state is D0 or D3
>>>> cold? The old behavior is to return 0, meanning success without taking
>>>> any actual action.
>>>> In acpi_bus_set_power, if the device is not power manageable, we will
>>>> return -ENODEV; in acpi_dev_pm_full/low_power, we will return 0 as in
>>>> the original acpi_device_set_power. So return -EINVAL here is correct?
>>> No, the original acpi_device_set_power() will return -ENODEV then, but
>>> in my opinion returning -EINVAL is more accurate, because "power
>>> manageable" means "you can change power state of it".
>> Shall I prepare a patch to update the errno in acpi_bus_set_power?
> In fact, it doesn't need to check flags.power_manageable after this patch
> and the debug message won't be missed I think, so please just remove
> the whole if () from there, if that's not a problem.

Patch to remove the redundant check, apply on top of this one.

From: Aaron Lu <>
Subject: [PATCH 1/3] ACPI / PM: Remove redundant check for power manageable in

Now that we will check if a device is power manageable in
acpi_device_set_power, it is no longer necessary to do this check in
acpi_bus_set_power, so remove it.

Signed-off-by: Aaron Lu <>
drivers/acpi/device_pm.c | 7 -------
1 file changed, 7 deletions(-)

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 63324b8..8270711 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -245,13 +245,6 @@ int acpi_bus_set_power(acpi_handle handle, int state)
if (result)
return result;

- if (!device->flags.power_manageable) {
- "Device [%s] is not power manageable\n",
- dev_name(&device->dev)));
- return -ENODEV;
- }
return acpi_device_set_power(device, state);

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