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    SubjectRe: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold
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    On Sun, 2012-04-01 at 13:56 +0800, Aaron Lu wrote:
    > Hi,
    >
    > On Sun, Apr 01, 2012 at 01:27:33PM +0800, Lin Ming wrote:
    > > > - if (device->power.states[state].flags.explicit_set) {
    > > > + /* If state is D3 Cold, try to evaluate _PS3 first */
    > > > + if (state == ACPI_STATE_D3_COLD) {
    > > > + explicit_set = (ps - 1)->flags.explicit_set;
    > > > + object_name[3] -= 1;
    > > > + }
    > >
    > > I'm not sure whether this works or not.
    > >
    > > From ACPI spec,
    > >
    > > _PS3 "is used to put the specific device into its D3hot or D3 state"
    > >
    > > D3 neither means D3hot nor D3cold. It's an old term before D3hot and
    > > D3cold were introduced.
    > I guess D3 has to mean something, right? :-)
    >
    > Here is the problem, there is no _PR3 in AMD's implementation, just _PS3.
    > And since _S0W evaluates 4, I've to put this device into D3 cold state
    > with _PS3.
    >
    > And the ACPI does have some words like:
    >
    > ------
    > Platform/drivers must assume that the device will have power completely
    > removed when the device is place into “D3” via _PS3
    > ------
    >
    > This is in section 7.2.11: _PR3.
    >
    > >
    > > Another problem:
    > >
    > > With your patch, both D3hot and D3cold will evaluate _PS3, right?
    > >
    > Yes.
    >
    > > Will it have problem on AMD platform if you try to put ODD into D3hot
    > > state? _PS3 is evaluated, so it actually enters D3Cold state.
    >
    > There is no D3 hot support for this device(from the firmware's
    > perspective), either it is at D0(via _PS0), or it will be at D3 cold(via
    > _PS3).

    But this is the generic code. We can't only consider some special
    device.

    Maybe we need some flag to tell which D3 state _PS3 is used for.

    Lin Ming

    >
    >
    > Thanks for the review.
    >
    > -Aaron
    >


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