_S0D and \_S0?

[Nate Lawson <nate-Y6VGUYTwhu0@public.gmane.org>]

After doing some more analysis, on ASL, it appears some systems (Dell)
have _S0D methods under devices.  It appears the OSPM should run those
at runtime when deciding to change the power state for a device.  Here's
an example:

            Device (USB3)
                Method (_S0D, 0, NotSerialized)
                {
                    Store (SMI (0x85, 0x00), Local0)
                    And (Local0, 0x01, Local0)
                    If (LEqual (Local0, 0x00))
                    {
                        Return (0x03)
                    }
                    Else
                    {
                        Return (0x00)
                    }
                }
                Name (_S1D, 0x02)
                Name (_S3D, 0x02)

This appears to say "if transitioning to another power state and the
system is up and running (i.e. S0), the device must always be powered off
(0x03) if bit 0 of SMI 0x85 is clear.  Otherwise, any power state is fine
(0x00)".

Additionally, some machines have non-zero values for \_S0.  Should we be
writing these values to the wake register at some point?

asl/vaio.asl:Name(_S0_, Package(0x4) {
asl/vaio.asl-    0x5,
asl/vaio.asl-    0x5,
asl/vaio.asl-    0x0,
asl/vaio.asl-    0x0,

Comments welcome.

-Nate


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