Hi Rafael,
On Thursday 21 Apr 2016 21:52:56 Rafael J. Wysocki wrote:
> On Thursday, April 21, 2016 02:52:55 AM Laurent Pinchart wrote:
> > The pm_runtime_force_suspend() and pm_runtime_force_resume() helpers are
> > designed to help driver being RPM-centric by offering an easy way to
> > manage runtime PM state during system suspend and resume. The first
> > function will force the device into runtime suspend at system suspend
> > time, while the second one will perform the reverse operation at system
> > resume time.
> >
> > However, the pm_runtime_force_resume() really forces resume, regardless
> > of whether the device was running or already suspended before the call
> > to pm_runtime_force_suspend(). This results in devices being runtime
> > resumed at system resume time when they shouldn't.
> >
> > Fix this by recording whether the device has been forcefully suspended
> > in pm_runtime_force_suspend() and condition resume in
> > pm_runtime_force_resume() to that state.
> >
> > All current users of pm_runtime_force_resume() call the function
> > unconditionally in their system resume handler (some actually set it as
> > the resume handler), all after calling pm_runtime_force_suspend() at
> > system suspend time. The change in behaviour should thus be safe.
> >
> > Signed-off-by: Laurent Pinchart
> > <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> > Reviewed-by: Kevin Hilman <khilman@xxxxxxxxxxxx>
>
> Ulf, any comments?
Ulf has proposed a different approach in "[PATCH] PM / Runtime: Defer resuming
of the device in pm_runtime_force_resume()". I agree that using usage_count is
better than introducing a new state flag in struct dev_pm_info, with a caveat:
it doesn't work properly :-). We would have to fix genpd first, as commented
in a reply to Ulf's patch.
> > ---
> >
> > drivers/base/power/runtime.c | 19 ++++++++++++++++---
> > include/linux/pm.h | 1 +
> > 2 files changed, 17 insertions(+), 3 deletions(-)
> >
> > Changes since v1:
> >
> > - Fix typos
> > - Protect the is_force_suspended flag modifications with power.lock
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 4c7055009bd6..8fc7fba811fa 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -1400,6 +1400,7 @@ void pm_runtime_init(struct device *dev)
> >
> > pm_suspend_ignore_children(dev, false);
> > dev->power.runtime_auto = true;
> >
> > + dev->power.is_force_suspended = false;
> >
> > dev->power.request_pending = false;
> > dev->power.request = RPM_REQ_NONE;
> > dev->power.deferred_resume = false;
> >
> > @@ -1457,6 +1458,7 @@ void pm_runtime_remove(struct device *dev)
> >
> > int pm_runtime_force_suspend(struct device *dev)
> > {
> >
> > int (*callback)(struct device *);
> >
> > + unsigned long flags;
> >
> > int ret = 0;
> >
> > pm_runtime_disable(dev);
> >
> > @@ -1475,6 +1477,10 @@ int pm_runtime_force_suspend(struct device *dev)
> >
> > goto err;
> >
> > pm_runtime_set_suspended(dev);
> >
> > + spin_lock_irqsave(&dev->power.lock, flags);
> > + dev->power.is_force_suspended = true;
> > + spin_unlock_irqrestore(&dev->power.lock, flags);
> > +
> >
> > return 0;
> >
> > err:
> > pm_runtime_enable(dev);
> >
> > @@ -1483,13 +1489,13 @@ err:
> > EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
> >
> > /**
> >
> > - * pm_runtime_force_resume - Force a device into resume state.
> > + * pm_runtime_force_resume - Force a device into resume state if needed.
> >
> > * @dev: Device to resume.
> > *
> > * Prior invoking this function we expect the user to have brought the
> > device * into low power state by a call to pm_runtime_force_suspend().
> > Here we reverse>
> > - * those actions and brings the device into full power. We update the
> > runtime PM - * status and re-enables runtime PM.
> > + * those actions and bring the device back to its runtime PM state before
> > forced + * suspension. We update the runtime PM status and re-enable
> > runtime PM.>
> > *
> > * Typically this function may be invoked from a system resume callback
> > to make * sure the device is put into full power state.
> >
> > @@ -1497,8 +1503,12 @@ EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
> >
> > int pm_runtime_force_resume(struct device *dev)
> > {
> >
> > int (*callback)(struct device *);
> >
> > + unsigned long flags;
> >
> > int ret = 0;
> >
> > + if (!dev->power.is_force_suspended)
> > + goto out;
> > +
> >
> > callback = RPM_GET_CALLBACK(dev, runtime_resume);
> >
> > if (!callback) {
> >
> > @@ -1510,6 +1520,9 @@ int pm_runtime_force_resume(struct device *dev)
> >
> > if (ret)
> >
> > goto out;
> >
> > + spin_lock_irqsave(&dev->power.lock, flags);
> > + dev->power.is_force_suspended = false;
> > + spin_unlock_irqrestore(&dev->power.lock, flags);
> >
> > pm_runtime_set_active(dev);
> > pm_runtime_mark_last_busy(dev);
> >
> > out:
> > diff --git a/include/linux/pm.h b/include/linux/pm.h
> > index 6a5d654f4447..bec15e0f244e 100644
> > --- a/include/linux/pm.h
> > +++ b/include/linux/pm.h
> > @@ -596,6 +596,7 @@ struct dev_pm_info {
> >
> > unsigned int use_autosuspend:1;
> > unsigned int timer_autosuspends:1;
> > unsigned int memalloc_noio:1;
> >
> > + unsigned int is_force_suspended:1;
> >
> > enum rpm_request request;
> > enum rpm_status runtime_status;
> > int runtime_error;
--
Regards,
Laurent Pinchart
