[Bug] ARM: mxs: STI: console can't wake up from freeze

[Stefan Wahren]

Hi Daniel,

> Daniel Lezcano <daniel.lezcano at linaro.org> hat am 5. November 2016 um 14:00
> geschrieben:
> 
> 
> On Sat, Nov 05, 2016 at 01:01:26PM +0100, Stefan Wahren wrote:
> 
> [ ... ]
> 
> > > > CONFIG_SUSPEND=y
> > > > CONFIG_SUSPEND_FREEZER=y
> > > > CONFIG_PM=y
> > > > CONFIG_CPU_IDLE is not set
> > > 
> > > hmmm, why not have CONFIG_CPU_IDLE set?
> > 
> > I'm using mxs_defconfig which doesn't select the ARM CPU idle. Is this
> > necessary?
> 
> Very likely :) suspend_freezer and cpuidle are tied together.
> 
> Moreover, while reading the code, it appears without CONFIG_CPU_IDLE the
> function cpuidle_idle_call is constantly failing, ending up by having the
> cpu looping again and again in the idle loop. The function stubs return
> -ENODEV in the cpuidle's header when CONFIG_CPU_IDLE is not set.
> 
> If I'm not wrong the traces should show the cpu actually does never go
> to suspend. As soon as it enters the state, it should exit immediately
> without an interrupt event.
> 
> Probably there is an inconsistent configuration leaving the kernel with
> a strange wakeup condition or a race with the short the suspend/resume
> cycle delay.
> 
> First test would be to enable CONFIG_CPU_IDLE.
> 
> If it is confirmed, it would be nice to feed bugzilla.

first i tried with CONFIG_CPU_IDLE=Y and then additionally with
CONFIG_ARM_CPUIDLE=y.

In both cases the issue is still reproducible.

As i wrote in my email before, i added a pr_info() into freeze_wake. But i never
see the output of this message. So i assume freeze_wake is never called. Again,
how could this happen?