Completes the TT-clear recovery path started in slice 2. Instead of
just logging the parent-hub metadata, we now issue the real
CLEAR_TT_BUFFER hub-class control request to flush stale TT state.
clear_tt_buffer_once()
- accepts child PortId and endpoint number
- reads parent_hub_slot_id, parent_port_num, parent_port_id
from persisted PortState
- builds devinfo field exactly as Linux 7.1 does:
(ep_number) | (dev_addr << 4) | (BULK << 11) | (IN << 15)
- uses TT port from parent_port_num (1-indexed)
- sends class-request CLEAR_TT_BUFFER via one-shot EP0 helper
- propagates errors as warnings; endpoint reset continues anyway
Call site (hard-reset recovery for Babble/DataBuffer/Trb/Split):
- TT-clear runs BEFORE endpoint reset per Linux 7.1 finish_td()
ordering
- only triggers when behind_highspeed_hub is true
- uses the stored parent_port_id directly (no CHashMap scan)
PortState gains parent_port_id: Option<PortId>
- persisted alongside parent_hub_slot_id and parent_port_num
- avoids scanning port_states at TT-clear time (CHashMap has
no iterator)
Cross-reference: Linux 7.1
- drivers/usb/core/hub.c: usb_hub_clear_tt_buffer()
- drivers/usb/host/xhci-ring.c: xhci_clear_hub_tt_buffer()
- driver_interface.rs: PortId definition
This completes the first implementation of P2-C error recovery:
- UsbTransaction: bounded soft retry (3x)
- Resource: bounded retry/backoff
- Stall: reset/restart + non-recursive device-side clear-halt
- Babble/DataBuffer/Trb/SplitTransaction: TT-clear (if behind HS hub)
+ hard endpoint reset
Red Bear OS
61b1510a46