PM regression with commit 5de85b9d57ab PM runtime re-init in v4.5-rc1

[Rafael J. Wysocki]

On Tue, Feb 2, 2016 at 10:39 PM, Tony Lindgren <tony at atomide.com> wrote:
> * Ulf Hansson <ulf.hansson at linaro.org> [160202 12:25]:
>> >
>> > ?  pm_runtime_put_sync() _already_ does not respect the autosuspend
>> > mode.  If you want to respect it, you have to call
>> > pm_runtime_put_sync_autosuspend() instead.
>>
>> Then there's a bug in the runtime PM core.
>>
>> From Tony's regression report and from mine own local runtime PM test
>> driver, I can see that the device doesn't get RPM_SUSPENDED (the
>> ->runtime_suspend() callback isn't called), even when the usage count
>> is zero - when pm_runtime_put_sync() is called.
> ...
>> Okay, so you are saying that the pm_runtime_put_sync() should idle the
>> device even if autosuspend is in use. That seems reasonable, I will
>> look into this problem.
>
> The patch below fixes pm_runtime_put_sync() to not respect the
> autosuspend mode to match what Alan is saying above. Seems to also
> fixes the $subject issue for me. And seems to behave for PM runtime
> for other devices during runtime too based on light testing here.
>
> Regards,
>
> Tony
>
> 8< ---------------
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -353,7 +353,9 @@ static int rpm_idle(struct device *dev, int rpmflags)
>
>   out:
>         trace_rpm_return_int(dev, _THIS_IP_, retval);
> -       return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
> +       if (!(rpmflags & RPM_IGNORE_AUTO))
> +               rpmflags |= RPM_AUTO;
> +       return retval ? retval : rpm_suspend(dev, rpmflags);
>  }
>
>  /**
> --- a/include/linux/pm_runtime.h
> +++ b/include/linux/pm_runtime.h
> @@ -23,6 +23,8 @@
>                                             usage_count */
>  #define RPM_AUTO               0x08    /* Use autosuspend_delay */
>
> +#define RPM_IGNORE_AUTO                0x10    /* Ignore autosuspend */
> +
>  #ifdef CONFIG_PM
>  extern struct workqueue_struct *pm_wq;
>
> @@ -241,7 +243,7 @@ static inline int pm_runtime_put_autosuspend(struct device *dev)
>
>  static inline int pm_runtime_put_sync(struct device *dev)
>  {
> -       return __pm_runtime_idle(dev, RPM_GET_PUT);
> +       return __pm_runtime_idle(dev, RPM_GET_PUT | RPM_IGNORE_AUTO);
>  }
>
>  static inline int pm_runtime_put_sync_suspend(struct device *dev)

This changes a well-documented behavior that someone may be relying on.

Not the safest thing to do I have to say.

Thanks,
Rafael