Re: [PATCH 1/4] PM / Wakeirq: Add minimal device wakeirq helper functions
From: Tony Lindgren
Date: Mon Mar 09 2015 - 12:46:43 EST
* Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> [150309 08:42]:
> On Mon, 9 Mar 2015, Tony Lindgren wrote:
> > > > > > Considering the above, should we add a new function something like
> > > > > > pm_resume_complete() that does not need irq_safe set but does
> > > > > > not return until the device has completed resume?
> > > > >
> > > > > That doesn't make sense. You're asking for a routine that is allowed
> > > > > to sleep but can safely be called in interrupt context.
> > > >
> > > > Oh it naturally would not work in irq context, it's for the bottom
> > > > half again.
> > >
> > > In other words, you're suggesting we add a function that runs in
> > > process context and doesn't return until the device is fully resumed?
> > > That's exactly what pm_runtime_resume does right now.
> > But doesn't it only wait for completion if the driver is marked with
> > pm_runtime_irq_safe()?
> Put it this way: pm_runtime_resume invokes a ->runtime_resume
> callback routine (the subsystem's or the driver's or whichever), and it
> assumes that if the routine returns 0 then the device has been resumed.
> It doesn't really _wait_ for anything; it just calls the callback
> It behaves this way whether or not the irq_safe flag is set. The only
> difference is that if irq_safe is set then the callback routine is
> invoked with interrupts disabled (and in this case pm_runtime_resume
> may be called in interrupt context -- normally it can be called only in
> process context).
Oh right you are. Looking at rpm_resume() again, it's the RPM_ASYNC that
was causing problems to me earlier, not the irq_safe. Sorry it seems I
was a bit confused. And yes, pm_runtime_resume() does not set RPM_ASYNC
like you pointed out earlier so no need to do anything there.
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