Re: [PATCH/RFC] pm: disabling runtime power-management has to reset the status

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On Fri, 15 Apr 2011, Guennadi Liakhovetski wrote:

> 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.

...

> > 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.

I see.  And is it true that you really do want to set the status to 
RPM_SUSPENDED without touching the hardware, i.e., without disabling 
any clocks or gating any power supplies?

If so, then your release routine should simply do

	pm_set_suspended(&pdev->dev);

after calling pm_runtime_disable().  There's no need to modify the 
runtime PM core.

Alan Stern

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