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

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

On Tue, Sep 25, 2012 at 01:52:03PM +0530, Poddar, Sourav wrote:

quoted

Hi Greg,

Ping on this?

On Tue, Sep 18, 2012 at 6:10 PM, Sourav Poddar [off-list ref] wrote:

quoted

Greg's tty-next is not booting on 2420 based N800. The failure is
observed at serial init itself. The reason might be that n800 tries to
resume even though it is not suspended before.

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 ?

-- 
balbi