Attention is currently required from: Felix Singer, Nico Huber, Martin Roth, Tim Wawrzynczak, Angel Pons, Subrata Banik.

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• File src/soc/intel/skylake/acpi/scs.asl:

  • Patch Set #5, Line 120: 0x4c4

    That's an interesting thought. My understanding was that with the _ADR
    above this "Device" would only be treated as present if it matches an
    enumerated PCI device in the OS.

    My understanding matches what you outlined here. However, I think the device will be enumerated in the OS unless it is power and clock gated before jumping into OS. This is where `ScsSdCardEnabled` seems to play a role. If the mainboard has initialized devicetree correctly to mark SD controller as `off`, then it should be power and clock gated by FSP, thus preventing it from showing up on the PCI bus.

    Would the OS try to switch power states of a PCI device that it can't see?

    My understanding is that if the OS doesn't see the device, then it won't really switch the power states for the device.

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