Re: [RFC][PATCH 1/3] PM / sleep: Move runtime PM barrier invocation to device_prepare()

Ulf Hansson
2014-05-13T09:16:34Z

On 13 May 2014 03:03, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Move the invocation of the runtime PM barrier during system suspend
> (or hibernation) from __device_suspend() to device_prepare() to make
> all runtime PM transitions in progress complete before executing
> ->prepare() callbacks for devices.
>
> That will allow those callbacks to check if devices are runtime
> suspended in a non-racy way.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/base/power/main.c | 31 +++++++++++++------------------
> 1 file changed, 13 insertions(+), 18 deletions(-)
>
> Index: linux-pm/drivers/base/power/main.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/main.c
> +++ linux-pm/drivers/base/power/main.c
> @@ -1312,24 +1312,7 @@ static int __device_suspend(struct devic
>
> dpm_wait_for_children(dev, async);
>
> - if (async_error)
> - goto Complete;
> -
> - /*
> - * If a device configured to wake up the system from sleep states
> - * has been suspended at run time and there's a resume request pending
> - * for it, this is equivalent to the device signaling wakeup, so the
> - * system suspend operation should be aborted.
> - */
> - if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
> - pm_wakeup_event(dev, 0);
> -
> - if (pm_wakeup_pending()) {
> - async_error = -EBUSY;
> - goto Complete;
> - }

I suppose you went a bit too far here!?

We can still have wakeup pending at this point, and thus we should
bail out, right?

> -
> - if (dev->power.syscore)
> + if (async_error || dev->power.syscore)
> goto Complete;
>
> dpm_watchdog_set(&wd, dev);
> @@ -1500,6 +1483,18 @@ static int device_prepare(struct device
> */
> pm_runtime_get_noresume(dev);
>
> + /*
> + * If a device configured to wake up the system from sleep states
> + * has been suspended at run time and there's a resume request pending
> + * for it, this is equivalent to the device signaling wakeup, so the
> + * system suspend operation should be aborted.
> + */
> + if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
> + pm_wakeup_event(dev, 0);
> +
> + if (pm_wakeup_pending())
> + return -EBUSY;
> +
> device_lock(dev);
>
> dev->power.wakeup_path = device_may_wakeup(dev);
>

Kind regards
Ulf Hansson