RE: Power management for ppc 85xx

Hi Clemens,

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Hello, Kumar, Hi, Marta!
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Glad I managed to make sense. I checked the hardware spec on the

board

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and it looks like we're using everything, apart from the SEC and

maybe

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the stand-alone I2C (I think we're just using the one within the

CMP).

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By the way, I made a mistake and the actual processor on the board

is

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the cut-down 8541, not the 8555. My apologies for that.

This morning I added some printks and confirmed that there is no

code

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behind pm_ops, so my question remains: is there some code out there
that
I can use? (hope so, otherwise I'm doomed...)

I'm sorry to say you're doomed.  I don't believe anyone's spent any
time trying to do pwr mgmt on 85xx.

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I am working with the MPC8540 in a mobile product and some
power saving would be fine to use. But I haven't seen any
power management code for that thingy in the kernels at all.
So, there is some work left there. Maybe I will have
a closer look in the future.
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According to some tests of a board manufacturer, the cpu
doesn't power down very much, when you stop some peripherals
or send the core to nap. But I wasn't able to confirm that yet.

We're estimating 2.5 watts saving on doze mode, in case that helps.
That's for a 8545 @ 800MHz

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Best greets,
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Clemens Koller
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Bfn,

Marta Chamorro