[Intel-gfx] [PATCH v2] PM / Runtime: Introduce pm_runtime_get_noidle

[Ulf Hansson]

[...]

>> >
>> > Which basically means you can call pm_runtime_resume() just fine,
>> > because it will do nothing if the status is RPM_ACTIVE already.
>> >
>> > So really, why don't you use pm_runtime_get_sync()?
>>
>> The difference would be that if the status is not RPM_ACTIVE already we
>> would drop the reference and report error. The caller would in this
>> case forego of doing something, since we the device is suspended or on
>> the way to being suspended. One example of such a scenario is a
>> watchdog like functionality: the watchdog work would
>> call pm_runtime_get_noidle() and check if the device is ok by doing
>> some HW access, but only if the device is powered. Otherwise the work
>> item would do nothing (meaning it also won't reschedule itself). The
>> watchdog work would get rescheduled next time the device is woken up
>> and some work is submitted to the device.
>
> So first of all the name "pm_runtime_get_noidle" doesn't make sense.
>
> I guess what you need is something like
>
> bool pm_runtime_get_if_active(struct device *dev)
> {
>         unsigned log flags;
>         bool ret;
>
>         spin_lock_irqsave(&dev->power.lock, flags);
>
>         if (dev->power.runtime_status == RPM_ACTIVE) {
>                 atomic_inc(&dev->power.usage_count);
>                 ret = true;
>         } else {
>                 ret = false;
>         }
>
>         spin_unlock_irqrestore(&dev->power.lock, flags);
> }
>
> and the caller will simply bail out if "false" is returned, but if "true"
> is returned, it will have to drop the usage count, right?
>
> Thanks,
> Rafael
>

Why not just:

pm_runtime_get_noresume():
if (RPM_ACTIVE)
  "do some actions"
pm_runtime_put();

Kind regards
Uffe