Re: PM(?) problems on v3.3-rc1 on OMAP3

Tomi Valkeinen
2012-01-23T08:53:14Z

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On Sun, 2012-01-22 at 22:11 +1100, NeilBrown wrote:

> This code disables the auto-idling of some clocks ... not entirely sure of
> the details.
>
> So it seems that it isn't a low power state but rather some clock being
> allowed to turn off which is the problem.
>
> I guess I could selective try denying idle on each clock domain until I find
> the one that is the problem..

I also did some testing: Normally DISPC's SIDLEMODE is set to smart idle
and MIDLEMODE to smart standby. Changing either of them to no idle or no
standby (respectively) removes the sync lost problem. But I guess that
doesn't tell much, except that the problem is some kind of idle/wakeup
problem.

Then I noticed that the DISPC's ENWAKEUP is not set. Setting ENWAKEUP
(with SIDLEMODE/IDLEMODE in smart mode) also removes the problem.

Again, my understanding of OMAP PM is rather limited, but could this be
the problem? Something (core/L3/whatever) goes to idle mode and when DSS
needs to fetch data or requires a clock, and DSS is not able to wake the
other component up?

Tomi

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