[PATCH v2 0/2] Introduce XHCI_FULL_RESET_ON_REMOVE quirk for DWC3

[Roy Luo <royluo@google.com>]

Commit 6ccb83d6c497 ("usb: xhci: Implement xhci_handshake_check_state()
helper") introduced an optimization to xhci_reset() during xhci removal,
allowing it to bail out early without waiting for the reset to complete.

This behavior can cause issues on SNPS DWC3 USB controller with dual-role
capability. When the DWC3 controller exits host mode and removes xhci
while a reset is still in progress, and then tries to configure its
hardware for device mode, the ongoing reset leads to register access
issues; specifically, all register reads returns 0. These issues extend
beyond the xhci register space (which is expected during a reset) and
affect the entire DWC3 IP block, causing the DWC3 device mode to
malfunction.

To fix this, introduce XHCI_FULL_RESET_ON_REMOVE quirk andd enable it on
DWC3. This ensures xhci_reset() completes its full handshake before
proceeding.

---
Changes in v2:
- no code change
- add Fixes tag and cc stable kernel
Link to v1: https://lore.kernel.org/r/20250515040207.1253690-1-royluo@google.com/
---

Roy Luo (2):
  xhci: Add a quirk for full reset on removal
  usb: dwc3: Force full reset on xhci removal

 drivers/usb/dwc3/host.c      | 5 ++++-
 drivers/usb/host/xhci-plat.c | 3 +++
 drivers/usb/host/xhci.c      | 8 +++++++-
 drivers/usb/host/xhci.h      | 1 +
 4 files changed, 15 insertions(+), 2 deletions(-)


base-commit: c94d59a126cb9a8d1f71e3e044363d654dcd7af8
-- 
2.49.0.1112.g889b7c5bd8-goog