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Re: Power Management Framework architectural design

On Apr 9, 2008, at 7:35 AM, Joerg Sonnenberger wrote:
On Wed, Apr 09, 2008 at 08:02:49AM +0000, Juha Keski-Saari wrote:
We are investigating architectural possibilities for a power management framework for NetBSD currently specifically for the ARM OMAP2 port, but we feel that such a design could benefit more than the users of the ARM
port. As we're still in the phase of architectural design, it is a
great time to give input and propose features that would make the
outcome more useful to more interest groups within the NetBSD community.

I've asked Matt for a dmesg of an actual system and it seems the ARM
device tree is quite flat. So the device central approach of PMF should
work quite well for this if obio registers a bus layer to do powering
down of unused part. You can use the idle time facility as well.
What currently is missing is proper high-level support for power domains
(e.g. multiple devices sharing power resources). Another item is lower
power states with wake up notification on events. That's something at
least useful in the context of USB and Firewire on all ports with
support for those, but I think it applies to other parts as well.

Please keep the discussion here on tech-kern, port-arm is too obscure
for the general topic :-)

Alas, the device tree doesn't match power domains at all.
Back when pmf was being designed, I strongly urged that it
include the concept of power domains under which device could
be grouped.

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