ARM: mxs: warnings on PM resume

[linux@armlinux.org.uk (Russell King - ARM Linux)]

On Sun, Jun 12, 2016 at 11:45:50PM +0200, Stefan Wahren wrote:
> Hi,
> 
> > Russell King - ARM Linux <linux@armlinux.org.uk> hat am 12. Juni 2016 um 15:54
> > geschrieben:
> > 
> > This isn't about the state of the interrupt controller.  It's about
> > the state of the IRQ mask bit in the CPUs CPSR.
> > 
> > irq_disabled() returns true when the I bit in CPSR is set, false
> > otherwise.
> > 
> > What it's pointing towards is some driver being unreasonable, and
> > clearing the CPUs CPSR I bit after the core PM code has set it.  Causes
> > can be using spin_lock_irq()/spin_unlock_irq()/local_irq_enable() etc
> > inappropriately, rather than using the irqsave/irqrestore versions.
> 
> i finally found the reason for the warning: clk_get_sys was called inside of
> mxs_suspend_enter.
> After moving it into the init function the issue disappear.

Hmm.  I suspect a faster way to have found that issue would be to build
your development kernels with more debugging options enabled - eg,
check that you have DEBUG_ATOMIC_SLEEP enabled.

That should have caught the attempt to take a mutex in an IRQs-disabled
region.

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