Implements the next recovery slice after the first active P2-C pass:
1. Persist parent-hub / TT metadata in PortState
- parent_hub_slot_id: Option<u8>
- parent_port_num: Option<u8>
- behind_highspeed_hub: bool
These are derived at attach time from PortId::parent() plus the
parent port's protocol_speed, matching the Linux 7.1 TT decision
rule: LS/FS device behind HS hub.
2. Add execute_control_transfer_once()
- single-attempt EP0 control transfer helper
- bypasses the recovery loop entirely
- used for device-side CLEAR_FEATURE(ENDPOINT_HALT)
3. Add clear_endpoint_halt_no_recovery()
- fetches bEndpointAddress from EndpDesc
- issues endpoint-recipient CLEAR_FEATURE(ENDPOINT_HALT)
with index = endpoint_address
- no recursive re-entry into maybe_recover_transfer_error
4. Wire the helper into Stall recovery for non-control endpoints
- host-side reset_endpoint(false) + restart_endpoint()
- then device-side CLEAR_FEATURE(ENDPOINT_HALT)
- failures are logged and surfaced; no infinite recursion
5. Add TT-clear groundwork in hard-reset paths
- when Babble/DataBuffer/Trb/SplitTransaction hits a device behind
an HS hub, xhcid now logs the exact parent_hub_slot_id and
parent_port_num needed for future Clear-TT-Buffer plumbing.
Cross-reference:
- Linux 7.1 drivers/usb/host/xhci-ring.c
* finish_td()
* xhci_halted_host_endpoint()
- Linux 7.1 drivers/usb/core/hub.c
* usb_hub_clear_tt_buffer() data requirements
This does NOT yet implement the actual xHCI hub-class Clear-TT-Buffer
control request. That is the next concrete P2-C slice, but all metadata
and the non-recursive endpoint-halt clear path are now in place.
Red Bear OS
ceb1a5799a