Re: Fail to enter retention

[Tony Lindgren <tony@atomide.com>]

* Ran Shalit <ranshalit@gmail.com> [141117 11:48]:
> >You need to look if you have some devices blocking deeper
> >idle states in cm_idlest*_core and cm_idlest_per registers.
> 
> >The device will automatically idle whatever it can if there
> >are no blockers. I believe at least EHCI still is blocking,
> >and MUSB if configured and cable connected.
> 
> I'll check the registers value, should I then try to modify this
> registers in order to get into retention ?

No, those are read-only status registers. You need idle the
drivers that show as blocking in those registers.

> I will still have to disable serial right ? Maybe some kernel process
> which run in background prevents retention ?

Yes otherwise the UART bits will show as blocking in those
registers.

> Is there some simple way to debug this or do I need to modify these registers ?

Just printing them out in the idle loop most likely will give
you the info you need.

Regards,

Tony