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

[Stefan Wahren]

> Daniel Lezcano <daniel.lezcano at linaro.org> hat am 6. November 2016 um 15:55
> geschrieben:
> 
> 
> On 06/11/2016 11:20, Stefan Wahren wrote:
> > Hi,
> > 
> >> Russell King - ARM Linux <linux at armlinux.org.uk> hat am 5. November 2016 um
> >> 19:05 geschrieben:
> >>
> >>
> >> On Sat, Nov 05, 2016 at 04:28:37PM +0100, Stefan Wahren wrote:
> >>> 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?
> >>
> >> Hmm, so the bit that you're getting stuck on is:
> >>
> >>         wait_event(suspend_freeze_wait_head,
> >>                    suspend_freeze_state == FREEZE_STATE_WAKE);
> >>
> > 
> > thanks for all the feedback. The real cause for this issue is in the irqchip
> > driver. I fixed it with this patch:
> 
> Mind to give some details ?
> 

No. AFAIK the serial_core already handles the suspend to idle. But it requires
that enable_irq_wake for the UART IRQ succeed. Unfortunately the irq-mxs (like a
couple of other irqchip drivers) neither implemented set_irq_wake or set
IRQCHIP_SKIP_SET_WAKE so enable_irq_wake will fail with -ENXIO and the UART
won't be setup as wakeup source. As the mxs interrupt controller doesn't provide
any facility to setup wakeup source i choose to use IRQCHIP_SKIP_SET_WAKE.

Instead of failing silently it would be better if sysfs won't allow to enable
wakeup source in this case or at least the serial core should complains about
it.