[PATCH 3/9] PM / Domains: Add APIs to attach/detach a power domain for a device

[Ulf Hansson]

On 27 August 2014 02:20, Rafael J. Wysocki <rjw at rjwysocki.net> wrote:
> On Tuesday, August 26, 2014 02:07:11 PM Ulf Hansson wrote:
>> To maintain scalability let's add common methods to attach and detach
>> a power domain for a device, dev_pm_domain_attach|detach().
>>
>> Typically dev_pm_domain_attach() shall be invoked from subsystem level
>> code at the probe phase to try to attach a device to it's power domain.
>> The reversed actions may be done a the remove phase and then by invoking
>> dev_pm_domain_detach().
>>
>> The supported power domains at this point are the ACPI and the generic
>> power domains.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
>> ---
>>  drivers/base/power/common.c | 58 +++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/pm.h          | 14 +++++++++++
>>  2 files changed, 72 insertions(+)
>>
>> diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
>> index df2e5ee..f544128 100644
>> --- a/drivers/base/power/common.c
>> +++ b/drivers/base/power/common.c
>> @@ -11,6 +11,8 @@
>>  #include <linux/export.h>
>>  #include <linux/slab.h>
>>  #include <linux/pm_clock.h>
>> +#include <linux/acpi.h>
>> +#include <linux/pm_domain.h>
>>
>>  /**
>>   * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
>> @@ -82,3 +84,59 @@ int dev_pm_put_subsys_data(struct device *dev)
>>       return ret;
>>  }
>>  EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
>> +
>> +/**
>> + * dev_pm_domain_attach - Attach a device to it's power domain.
>> + * @dev: Device to attach.
>> + * @power_on: Used to indicate whether we should power on the device.
>> + *
>> + * The @dev may only be attached to a single power domain. By iterating through
>> + * the available alternatives we try to find a valid domain for the device.
>> + *
>> + * This function should typically be invoked from subsystem level code during
>> + * the probe phase. Especially for those that's hold devices which requires
>> + * power management through power domains.
>> + *
>> + * Callers must ensure proper synchronization of this function with power
>> + * management callbacks.
>> + *
>> + * Returns 0 on successfully attached power domain or negative error code.
>> + */
>> +int dev_pm_domain_attach(struct device *dev, bool power_on)
>> +{
>> +     int ret;
>> +
>> +     ret = acpi_dev_pm_attach(dev, power_on);
>> +     if (ret == -EPROBE_DEFER)
>
> This doesn't seem to be possible today.  At least I'm not sure how it can
> happen.

You are right, but I did this intentionally. The reason for having
this check, was that I didn't want the new API to put the limit on
handling deferred probe.

I happy the above check, if you think it's better!?

Kind regards
Uffe

>
>> +             return ret;
>> +     else
>> +             ret = genpd_dev_pm_attach(dev);
>> +
>> +     return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
>
> On a more general note, are you sure that the place where we call
> acpi_dev_pm_attach() will always be suitable for calling genpd_dev_pm_attach()?
>

Currently, I haven't seen any place where it doesn't make sense.

Additionally if such place is found, we may either just ignore it and
let the caller of the API worry about the returned error or invoke the
genpd/acpi API immediately instead.

>> +
>> +/**
>> + * dev_pm_domain_detach - Detach a device from it's power domain.
>> + * @dev: Device to attach.
>> + * @power_off: Used to indicate whether we should power off the device.
>> + *
>> + * The @dev may be attached to a power domain. By iterating through the
>> + * available alternatives we detach it from it's power domain.
>> + *
>> + * This functions will reverse the actions from dev_pm_domain_attach() and
>> + * thus detach the @dev from it's power domain. Typically it should be invoked
>> + * from subsystem level code during the remove phase.
>> + *
>> + * Callers must ensure proper synchronization of this function with power
>> + * management callbacks.
>> + *
>> + * Returns 0 on successfully detached power domain or negative error code.
>> + */
>> +int dev_pm_domain_detach(struct device *dev, bool power_off)
>> +{
>> +     if (acpi_dev_pm_detach(dev, power_off))
>> +             return genpd_dev_pm_detach(dev);
>> +     return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
>> diff --git a/include/linux/pm.h b/include/linux/pm.h
>> index 72c0fe0..8176b07 100644
>> --- a/include/linux/pm.h
>> +++ b/include/linux/pm.h
>> @@ -621,6 +621,20 @@ struct dev_pm_domain {
>>       struct dev_pm_ops       ops;
>>  };
>>
>> +#ifdef CONFIG_PM
>> +extern int dev_pm_domain_attach(struct device *dev, bool power_on);
>> +extern int dev_pm_domain_detach(struct device *dev, bool power_off);
>> +#else
>> +static inline int dev_pm_domain_attach(struct device *dev, bool power_on)
>> +{
>> +     return -ENODEV;
>> +}
>> +static inline int dev_pm_domain_detach(struct device *dev, bool power_off)
>> +{
>> +     return -ENODEV;
>> +}
>> +#endif
>> +
>>  /*
>>   * The PM_EVENT_ messages are also used by drivers implementing the legacy
>>   * suspend framework, based on the ->suspend() and ->resume() callbacks common
>>
>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.