On Fri, 15 Apr 2011, Alan Stern wrote:
> On Fri, 15 Apr 2011, Guennadi Liakhovetski wrote:
>
> > Restore the initial RPM_SUSPENDED runtime pm status, when disabling,
> > otherwise the following enable will not function. This happens, e.g.,
> > when unloading and reloading drivers.
> >
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> > Cc: Simon Horman <horms@xxxxxxxxxxxx>
> > Cc: Magnus Damm <damm@xxxxxxxxxxxxx>
> > ---
> >
> > No, I do not claim to understand the thousand of states, flags, and
> > counters, this just happens to fix the problem for me. Feel free to make a
> > correct solution out of this.
> >
> > drivers/base/power/runtime.c | 4 +++-
> > 1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 3172c60..83d6898 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -1012,8 +1012,10 @@ void __pm_runtime_disable(struct device *dev, bool check_resume)
> > pm_runtime_put_noidle(dev);
> > }
> >
> > - if (!dev->power.disable_depth++)
> > + if (!dev->power.disable_depth++) {
> > __pm_runtime_barrier(dev);
> > + dev->power.runtime_status = RPM_SUSPENDED;
> > + }
> >
> > out:
> > spin_unlock_irq(&dev->power.lock);
>
> This certainly doesn't look right. Can you explain in more detail the
> problem you are trying to solve?
Yes, I can. On the first loading of an MMC driver, which does the standard
pm_runtime_enable(&pdev->dev);
ret = pm_runtime_resume(&pdev->dev);
in .probe() and
pm_runtime_disable(&pdev->dev);
in .release() (see [1]), with an inserted card, on the first modprobe I
see a full pm-runtime run down to platform_pm_runtime_resume() and to
platform_pm_runtime_suspend() on rmmod. On a repeated modprobe
platform_pm_runtime_resume() does not get called, because
dev->power.runtime_status != RPM_SUSPENDED, instead, it is still
RPM_ACTIVE, so, rpm_resume() exits prematurily.
[1] http://thread.gmane.org/gmane.linux.kernel.mmc/7364
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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