[Letux-kernel] [PATCHv2] i2c: omap: Use noirq system sleep pm ops to idle device for suspend

[Andreas Kemnade]

On Thu, 21 Feb 2019 14:39:55 -0800
Tony Lindgren <tony at atomide.com> wrote:

> * Andreas Kemnade <andreas at kemnade.info> [190221 22:37]:
> > On Thu, 21 Feb 2019 14:25:32 -0800
> > Tony Lindgren <tony at atomide.com> wrote:
> >   
> > > * Andreas Kemnade <andreas at kemnade.info> [190221 22:14]:  
> > > > On Thu, 21 Feb 2019 13:41:57 -0800
> > > > Tony Lindgren <tony at atomide.com> wrote:    
> > > > > I tried with just plain omap2plus_defconfig, do you have maybe
> > > > > something extra enabled that I don't?
> > > > >     
> > > > A quick guess:
> > > > CONFIG_PREEMPT=y    
> > > 
> > > Hmm I just tried adding that and it still works here.
> > >   
> > > > my config:
> > > > https://misc.andi.de1.cc/mydef
> > > > 
> > > > omap2plus_defconfig works here also. Now I need some sleep.    
> > > 
> > > Maybe you have a USB cable connected and the USB PHY is
> > > producing interrupts on resume? My test devices are in a
> > > rack so it's a bit hard for me to quickly test that.
> > >   
> > usb irqs would not explain why waking up via other pinctrl does not
> > cause these problems. phy modules are not loaded.
> > 
> > So, now really brain sleep time here, hopefully a resume with fresh
> > ideas.  
> 
> OK, good night. I booted your config with 8250 + nfsroot added
> and I'm still unable to reproduce your issue here.
> 
so you have more modules loaded than me when trying that.
Hmm, so what do we know:
- git bisect at least led to something interesting, not some unrelated thing.
    which might just cause timing differences.
- rtcwake + actual wakeup via rtc on my config = problem
- rtcwake + actual wakeup via some other pin in the wkup domain = no problem
- rtcwake + actual wakeup via powerbutton (twl4030-pwrbutton) = problem
- omap2plus_defconfig seems to work here
- no problems at other systems with dm3730 + twl4030 with my config
  and with omap2plus defconfig

I deduce that there happens something strange at resume independant
from what happend at suspend. Probably some timing issue.

Hmm, does "bisecting" omap2_defconfig and my config give some helpful
information? Besides of some key points like CONFIG_PREEMPT, I will probably
just find things which somehow influence timing a little, so I will probably
end up without anything interesting. Hopefully it will not just fix something.

I will try to add printks to find out in which order things happen.
We have
enable_irq_wake(irq_num);
in twl4030-irq.c: Does that has any interersting consequences? sys_nirq seems
to be equal on non-affected and affected systems (pinmux + twl irq config)

Regards,
Andreas
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