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

Hi,

On Tue, Sep 25, 2012 at 10:21:18AM +0100, Russell King - ARM Linux wrote:

On Tue, Sep 25, 2012 at 12:11:14PM +0300, Felipe Balbi wrote:

quoted

On Tue, Sep 25, 2012 at 10:12:28AM +0100, Russell King - ARM Linux wrote:

quoted

On Tue, Sep 25, 2012 at 11:31:20AM +0300, Felipe Balbi wrote:

quoted

On Tue, Sep 25, 2012 at 09:30:29AM +0100, Russell King - ARM Linux wrote:

quoted

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!

why are you always so over the top like that ? This is just
counter-productive to say the least.

What I'm trying to say here, is that there might be a bug either on pm
core or on OMAP3's implementation and I'd like to get input from Tony,
Santosh, Paul, etc before going forward. Maybe it's something they've
already been through, or maybe it rings a bell and points to somewhere
we should look for.

anyway, instead of feeding your ego, we can stop this discussion and let
Sourav see what he can come up with.

-- 
balbi