Mikhail ChusavitinandClaude Sonnet 5
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pcie-link's retrain check compared post-retrain speed against a port's max capability without checking whether anything was actually seated downstream. A switch downstream port with no card plugged in retrains to zero lanes but still reports a reset-state speed, so it was misreported as "retrained to Gen1, capable of Gen5" — indistinguishable from a real degraded link. Now a port that was already empty before the retrain is skipped (same treatment as a disabled device: legitimately unpopulated slots are common and shouldn't fail the check), while a device that answered before the retrain and disappeared right after it still fails, with an honest "no device detected downstream" message instead of a fabricated speed reading. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>