Cross-referenced with Linux 7.1 drivers/usb/host/xhci-pci.c.
main.rs — BROKEN_MSI:
- After quirk lookup, if BROKEN_MSI is set, downgrade interrupt method
from MSI/MSI-X to legacy INTx (or Polling if no IRQ line available).
Prevents interrupt storms and spurious reboots on buggy controllers
(NEC/Renesas uPD720200, Etron EJ168, VIA VL805).
mod.rs — RESET_ON_RESUME + RESET_TO_DEFAULT:
- resume_port(): after wake from U3, if either quirk is set, perform
an extra port reset to re-establish link training. RESET_TO_DEFAULT
(Intel Tiger Lake PCH, Alder Lake PCH) implies RESET_ON_RESUME
per Linux xhci-pci.c init path.
- Prevents USB 3.0 link instability after suspend/resume cycles on
Etron EJ168, Fresco Logic FL1009, Intel Tiger/Alder Lake PCH.
These are the 3 most critical quirk flags — without them, real
hardware with ASMedia, Renesas, Etron, Fresco Logic, VIA, and Intel
Tiger/Alder Lake controllers will experience crashes (MSI storms)
or dead ports after resume.
Previous quirk enforced: NO_SOFT_RETRY (scheme.rs:600).
Previous quirk effectively enforced: AVOID_BEI (always false).
Total quirk flags now RUNTIME-ENFORCED: 5/50 (+4 from 1).
Red Bear OS
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