should respond with all zeroes to any access to slave registers. Test with
PATA devices confirmed such behavior. Unluckily, Intel SATA controllers in
legacy emulation mode behave differently, not making any difference between
ATA and ATAPI devices. It causes false positive slave device detection and,
as result, command timeouts.
To workaround this problem, mask result of legacy-emulated soft-reset with
the device presence information received from the SATA-specific registers.
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