Re: [PATCHv2 12/19] ARM: OMAP4: PM: update ROM return address for OSWR and OFF

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On Wed, 2012-05-16 at 16:36 -0700, Kevin Hilman wrote:
> Tero Kristo <t-kristo@xxxxxx> writes:
> > From: Carlos Leija <cileija@xxxxxx>
> >
> > At wakeup from OFF/OSWR CPU1 will call secure HAL service through a local
> > secure dispatcher with MMU off, 
> Reviewers who are uninitaited in this level of detail need some more
> help here  (even those who are deeply familiar will need more help in a
> few months when they forget the details.)
> So, some more detail about where this is in the code would be helpful
> here.
> > thus ROM will save a PA return address.
> > Later in the wakeup, when SMC driver calls an RPC through
> > omap4_secure_dispatcher (MMU is on now), 
> Again, pointer to where is this in the code would be helpful.

I believe this refers to any of the SMC calls done in the ASM files.
Most notably the one in omap-headsmp.S, which is added (rather)
illogically after this patch in the set though.

> Also, it's not obvious why RPC use used here. Is that referring to the
> fact that the secure calls on CPU1 are dispatched to CPU0?  Whatever it
> means, it should be summarized in the changelog.

Not sure about this, maybe security guys can comment on this.

> > ROM code won't log the new return
> > address as RPCs are handled different. Thus ROM will attempt to return to
> > a PA address when the MMU is on and the system will hang.
> >
> > We need to do this for OSWR state and OFF state of mpu power domain,
> > not just for device off(mpu pd OFF).
> The code suggests that affects *all* OMAP4 revisions?  Is that correct?

I think thats right.

> And once again, can this be implmented using cluster PM notifiers, where
> the notifier is registered only on affected revisions?

Should be okay to do that. I guess this should move to omap-secure.c.

> (Sheesh, the number of ROM code workaounds in this series is rather
> disconcerting.)
> Kevin

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