[v3,4/4] PM / wakeup: Print warn if device gets enabled as wakeup source during sleep

In general, wakeup settings are not supposed to be changed during any of
the system wide PM phases. The reason is simply that it would break
guarantees provided by the PM core, to properly act on active wakeup
sources.

However, there are exceptions to when, in particular, disabling a device as
wakeup source makes sense. For example, in cases when a driver realizes
that its device is dead during system suspend. For these scenarios, we
don't need to care about acting on the wakeup source correctly, because a
dead device shouldn't deliver wakeup signals.

To this reasoning and to help users to properly manage wakeup settings,
let's print a warning in cases someone calls device_wakeup_enable() during
system sleep.

Suggested-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

---
 drivers/base/power/wakeup.c | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.7.4

On Tue, Jan 2, 2018 at 5:08 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> In general, wakeup settings are not supposed to be changed during any of

> the system wide PM phases. The reason is simply that it would break

> guarantees provided by the PM core, to properly act on active wakeup

> sources.

>

> However, there are exceptions to when, in particular, disabling a device as

> wakeup source makes sense. For example, in cases when a driver realizes

> that its device is dead during system suspend. For these scenarios, we

> don't need to care about acting on the wakeup source correctly, because a

> dead device shouldn't deliver wakeup signals.

>

> To this reasoning and to help users to properly manage wakeup settings,

> let's print a warning in cases someone calls device_wakeup_enable() during

> system sleep.

>

> Suggested-by: Rafael J. Wysocki <rafael@kernel.org>

> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

> ---

>  drivers/base/power/wakeup.c | 3 +++

>  1 file changed, 3 insertions(+)

>

> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c

> index b7b8b2f..272c44b 100644

> --- a/drivers/base/power/wakeup.c

> +++ b/drivers/base/power/wakeup.c

> @@ -268,6 +268,9 @@ int device_wakeup_enable(struct device *dev)

>         if (!dev || !dev->power.can_wakeup)

>                 return -EINVAL;

>

> +       if (pm_suspend_target_state != PM_SUSPEND_ON)

> +               dev_warn(dev, "don't enable as wakup source during sleep!\n");

> +

>         ws = wakeup_source_register(dev_name(dev));

>         if (!ws)

>                 return -ENOMEM;

> --


It looks like we need to defer this until we fix a couple of issues ...

Thanks,
Rafael

On 6 January 2018 at 00:57, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Tue, Jan 2, 2018 at 5:08 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:

>> In general, wakeup settings are not supposed to be changed during any of

>> the system wide PM phases. The reason is simply that it would break

>> guarantees provided by the PM core, to properly act on active wakeup

>> sources.

>>

>> However, there are exceptions to when, in particular, disabling a device as

>> wakeup source makes sense. For example, in cases when a driver realizes

>> that its device is dead during system suspend. For these scenarios, we

>> don't need to care about acting on the wakeup source correctly, because a

>> dead device shouldn't deliver wakeup signals.

>>

>> To this reasoning and to help users to properly manage wakeup settings,

>> let's print a warning in cases someone calls device_wakeup_enable() during

>> system sleep.

>>

>> Suggested-by: Rafael J. Wysocki <rafael@kernel.org>

>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

>> ---

>>  drivers/base/power/wakeup.c | 3 +++

>>  1 file changed, 3 insertions(+)

>>

>> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c

>> index b7b8b2f..272c44b 100644

>> --- a/drivers/base/power/wakeup.c

>> +++ b/drivers/base/power/wakeup.c

>> @@ -268,6 +268,9 @@ int device_wakeup_enable(struct device *dev)

>>         if (!dev || !dev->power.can_wakeup)

>>                 return -EINVAL;

>>

>> +       if (pm_suspend_target_state != PM_SUSPEND_ON)

>> +               dev_warn(dev, "don't enable as wakup source during sleep!\n");

>> +

>>         ws = wakeup_source_register(dev_name(dev));

>>         if (!ws)

>>                 return -ENOMEM;

>> --

>

> It looks like we need to defer this until we fix a couple of issues ...


Yes.

Or, perhaps changing from dev_warn() to dev_dbg(), as it could provide
us with some more detailed information, compared to a "git grep"
research?

Kind regards
Uffe

On Mon, Jan 8, 2018 at 12:13 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On 6 January 2018 at 00:57, Rafael J. Wysocki <rafael@kernel.org> wrote:

>> On Tue, Jan 2, 2018 at 5:08 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:

>>> In general, wakeup settings are not supposed to be changed during any of

>>> the system wide PM phases. The reason is simply that it would break

>>> guarantees provided by the PM core, to properly act on active wakeup

>>> sources.

>>>

>>> However, there are exceptions to when, in particular, disabling a device as

>>> wakeup source makes sense. For example, in cases when a driver realizes

>>> that its device is dead during system suspend. For these scenarios, we

>>> don't need to care about acting on the wakeup source correctly, because a

>>> dead device shouldn't deliver wakeup signals.

>>>

>>> To this reasoning and to help users to properly manage wakeup settings,

>>> let's print a warning in cases someone calls device_wakeup_enable() during

>>> system sleep.

>>>

>>> Suggested-by: Rafael J. Wysocki <rafael@kernel.org>

>>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

>>> ---

>>>  drivers/base/power/wakeup.c | 3 +++

>>>  1 file changed, 3 insertions(+)

>>>

>>> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c

>>> index b7b8b2f..272c44b 100644

>>> --- a/drivers/base/power/wakeup.c

>>> +++ b/drivers/base/power/wakeup.c

>>> @@ -268,6 +268,9 @@ int device_wakeup_enable(struct device *dev)

>>>         if (!dev || !dev->power.can_wakeup)

>>>                 return -EINVAL;

>>>

>>> +       if (pm_suspend_target_state != PM_SUSPEND_ON)

>>> +               dev_warn(dev, "don't enable as wakup source during sleep!\n");

>>> +

>>>         ws = wakeup_source_register(dev_name(dev));

>>>         if (!ws)

>>>                 return -ENOMEM;

>>> --

>>

>> It looks like we need to defer this until we fix a couple of issues ...

>

> Yes.

>

> Or, perhaps changing from dev_warn() to dev_dbg(), as it could provide

> us with some more detailed information, compared to a "git grep"

> research?


That would work too.

Thanks,
Rafael