[RFT/PATCH] serial: omap: prevent resume if device is not suspended.

[Russell King - ARM Linux]

On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote:
> On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote:
> > On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote:
> > > On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote:
> > > > How is this happening?  I think that needs proper investigation - or if
> > > > it's had more investigation, then the results needs to be included in
> > > > the commit description so that everyone can understand the issue here.
> > > > 
> > > > We should not be resuming a device which hasn't been suspended.  Maybe
> > > > the runtime PM enable sequence is wrong, and that's what should be fixed
> > > > instead?  
> > > > 
> > > > This sequence in the probe() function:
> > > > 
> > > >         pm_runtime_irq_safe(&pdev->dev);
> > > >         pm_runtime_enable(&pdev->dev);
> > > >         pm_runtime_get_sync(&pdev->dev);
> > > > 
> > > > would enable runtime PM while the s/w state indicates that it's disabled,
> > > > and then that pm_runtime_get_sync() will want to resume the device.  See
> > > > the section "5. Runtime PM Initialization, Device Probing and Removal"
> > > > in Documentation/power/runtime_pm.txt, specifically the second paragraph
> > > > of that section.
> > > 
> > > that was tested. It worked in pandaboard but didn't work on beagleboard
> > > XM. Sourav tried to start a discussion about that, but it simply died...
> > > 
> > > In any case, pm_runtime_get_sync() in probe will always call
> > > runtime_resume callback, right ?
> > 
> > Well, if the runtime PM state says it's suspended, and then you enable
> > runtime PM, the first call to pm_runtime_get_sync() will trigger a resume
> > attempt.  The patch description is complaining about resume events without
> > there being a preceding suspend event.
> > 
> > This could well be why.
> 
> that's most likely, of course. But should we cause a regression to
> beagleboard XM because of that ?

What would cause a regression on beagleboard XM?  I have not suggested
any change other than more investigation of the issue and a fuller patch
description - yet you're screaming (idiotically IMHO) that mere
investigation would break beagleboard.

Well, if it's _that_ fragile, that mere investigation of this issue by
someone elsewhere on the planet would break your beagleboard, maybe it
deserves to be broken!