On Wednesday, December 15, 2010, Rafael J. Wysocki wrote:
> On Wednesday, December 15, 2010, Rafael J. Wysocki wrote:
> > On Tuesday, December 14, 2010, Alan Stern wrote:
> > > On Tue, 14 Dec 2010, Rabin Vincent wrote:
> > >
> > > > Hello,
> > > >
> > > > If an i2c driver uses dev_pm_ops and pm_runtime_suspended() returns true
> > > > for the device, the i2c core will not call the driver's pm->suspend()
> > > > routine. Similar behaviour (except for the if dev_pm_ops check) is
> > > > present in the generic PM ops provided in
> > > > drivers/base/power/generic_ops.c.
> > > >
> > > > Since pm_runtime_suspended() returns true if the relevant driver did not
> > > > call any pm_runtime functions, this means that any driver which does not
> > > > use pm_runtime APIs will not get its pm->suspend() callback called
> > > > during system sleep, if CONFIG_PM_RUNTIME is enabled.
> > > >
> > > > For the i2c case, there are several such drivers (in drivers/input/*,
> > > > etc) lacking these calls. How is this to be handled? Do all of these
> > > > drivers need to be patched to use the pm_runtime API if they are to be
> > > > used on a kernel with PM_RUNTIME enabled?
> > >
> > > I'm not familiar with the details of how the i2c subsystem works. But
> > > in general, the subsystem code should call pm_runtime_set_active()
> > > for every device before registering it. Then if a driver doesn't use
> > > any runtime-PM functions, pm_runtime_suspended() will return false.
> >
> > I rather think that our current definition of pm_runtime_suspended() is
> > not really adequate.
> >
> > Namely, it shouldn't really return true if runtime PM is not enabled
> > (ie. power.disable_depth > 1).
>
> That should have been power.disable_depth > 0, of course. Sorry.
>
> > That change would fix the issue at hand, wouldn't it?
Below is a patch. I don't think it needs to be done under the lock at
the moment if the callers of pm_runtime_enable() always remember to set
the appropriate device status before calling it.
Thanks,
Rafael
---
From: Rafael J. Wysocki <rjw@xxxxxxx>
Subject: PM / Runtime: Fix pm_runtime_suspended()
pm_runtime_suspended() shouldn't return true if the runtime PM of the
given device is disabled.
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
include/linux/pm_runtime.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
Index: linux-2.6/include/linux/pm_runtime.h
===================================================================
--- linux-2.6.orig/include/linux/pm_runtime.h
+++ linux-2.6/include/linux/pm_runtime.h
@@ -78,7 +78,8 @@ static inline void device_set_run_wake(s
static inline bool pm_runtime_suspended(struct device *dev)
{
- return dev->power.runtime_status == RPM_SUSPENDED;
+ return dev->power.runtime_status == RPM_SUSPENDED
+ && !dev->power.disable_depth;
}
static inline void pm_runtime_mark_last_busy(struct device *dev)
--
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