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asmc: prefer MMIO backend over PIO when both are present
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Authored by seuros on Fri, Aug 14, 8:37 AM.
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Details

Summary

T2, T1, and some pre-T1 Macs advertise a legacy PIO
range in the SMC ACPI _CRS alongside a live MMIO window, but the
silicon behind the PIO range is bogus.

Try MMIO first, validate via LDKN >= 2, fall back to PIO if that
fails or no MMIO resource is present. Drop "(T2)" from the backend
message since MMIO isn't T2-exclusive.

MFC: 1 week

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rG FreeBSD src repository
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