[PATCHv9 0/8] ARM: OMAP4: core retention support

[Tero Kristo]

On Tue, 2012-11-06 at 13:19 -0800, Kevin Hilman wrote:
> Tero Kristo <t-kristo at ti.com> writes:
> 
> > Hi Kevin,
> >
> > On Mon, 2012-11-05 at 14:23 -0800, Kevin Hilman wrote:
> >> Hi Tero,
> >> 
> >> Tero Kristo <t-kristo at ti.com> writes:
> >> 
> >> > Hi,
> >> >
> >> > Changes compared to previous version:
> >> > - rebased on top of 3.7-rc1
> >> > - applies on top of latest func pwrst code (v6)
> >> > - added back patch #1 to this set (it wasn't queued yet after all)
> >> > - added patch #7 for fixing a bug in the functional pwrst code
> >> > - added patch #8 for fixing a regression with MUSB PHY power handling
> >> >   (not quite sure if this is the correct way to fix this or not)
> >> >
> >> > Tested with omap4460 gp panda + omap4430 emu blaze boards, with cpuidle +
> >> > suspend.
> >> >
> >> > Branch also available here:
> >> > git://gitorious.org/~kristo/omap-pm/omap-pm-work.git
> >> > branch: mainline-3.7-rc1-omap4-ret-v9
> >> 
> >> I tested this branch on 4430/Panda and 4460/Panda-ES and I'm seeing
> >> several domains not hitting target power state in suspend[1].
> >> 
> >> Am I missing some other fixes?  Using omap2plus_defconfig, I tried your
> >> branch alone, and merged with v3.7-rc4, and I get the same errors.
> 
> [...]
> 
> > This looks like a combination of boot loader/kernel problems. My guess
> > is that l3init is probably held on by the USB, and both ivahd / tesla
> > are held on by some DSP/IVA modules which are not idling properly.
> >
> > The last patch in this set should fix the USB problems at least
> > partially, but also the USB DPLL itself might be in wrong state,
> > attached patch might help for that one and get l3init to idle.
> >
> > For DSP I don't have a patch right now, what is the boot loader you are
> > using? (Can you provide git / commit / config info?)
> 
> I was using mainline u-boot at tag v2012.04.01 when I saw the errors.  
> 
> To check the bootloader, I upgraded to the latest mainline tag
> (v2012.10) and the problems are gone on both 4430/Panda and
> 4460/Panda-ES...   Interesting.
> 
> That suggests that there's still some kernel assumptions/dependencies on
> the bootloader that need to be addressed.

After a little bit of looking into this, this is pretty similar to what
I was working on quite a while back once I tried to get the core ret
work with mainline kernel. I ended up sending patches against the
boot-loader as there wasn't a readily visible solution to some of the
issues on kernel side => so now if you update the u-boot, it gets fixed.

I am seeing (at least) following subsystems being non-idle with the old
bootloader:
- M3 cortex (stuck in transition)
- DSP (stuck in transition)
- SL2IF (stuck in transition)
- FSUSB (stuck in transition)

...but I am not aware of any way to get these to working properly from
this state without POR. Some of them probably require firmware to be
loaded and letting them out of reset also (M3 / DSP.) Benoit, do you
have any clues?

-Tero