GTA04 PMU / Core arch block diagram v1

Werner Almesberger werner at
Tue Apr 1 23:43:14 CEST 2008

Andy Green wrote:
> Corner cases like hangup action, reacting to mute, going to handsfree
> and plugging the headphones in should be instant with no deadtime if the
> CPU is there or not.

Hmm, I'm just a bit afraid that we may end up building yet another
u-boot if the MPU gets to do too much. Small tight real-time things
(such as speaking HDQ), high-frequency events (integration of
accelerometer results), and low-level power management (PMU bringup),
yes, by all means, but things like hangup management sound rather
like the sort of policy best done in user space to me ...

> It'll be welcome to get faster but it is still deadtime.  If we do it
> right what the MPU services can be really uber solid with zero deadtime,
> giving cover to hide that Linux might be coming up for example.

Well, all we really have to do before the CPU can make decisions is
go through reset, crank up the PLLs, and bring the DRAM out of
sleep. That should be measured in milliseconds and fast enough for
most user interactions.

So I'd rather fix that general bug (resume being slowed down to a
crawl by extreme overhead), instead of constructing an elaborate

> Well, I don't mind it at all, but the image is just for the core part, I
> didn't mean to capture all the possibilities (there are other
> peripherals off 6410 like camera and so on).

Okay, fair enough. We can leave some details for the real schematics :-)

- Werner

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