The round-2 stub audit confirmed that the ohcid driver's
bulk_transfer and interrupt_transfer (the only OHCI-specific
breaking stubs from the v4.8 audit) were NOT fixed by the
W1-W8 pass. They returned Err(UsbError::Unsupported) at
src/main.rs:275 and :287. This was the single CRITICAL gap
left after the previous round.
Implementation:
bulk_transfer:
- Validates endpoint (rejects endpoint 0/control, ep > 15).
- Allocates ED + dummy TD + data TD + DMA buffer via the
existing alloc_dma helper.
- Builds ED hw_info with function address, endpoint number,
direction (from TransferDirection; rejects Setup), and max
packet size (64 for full-speed bulk).
- Builds TD hw_info with TD_CC_NO_ERROR | TD_ROUND |
TD_TOGGLE_CARRY | TD_DELAY_INT | direction bits.
- Sets ED head_p = data-TD phys, tail_p = dummy phys.
- Writes HC_BULK_HEAD_ED and clears HC_BULK_CURRENT_ED.
- Ensures CTRL_BLE is set in HC_CONTROL.
- Kicks the bulk list by writing HC_CMD_STATUS with CMD_BLF
(1<<2).
- Polls HC_DONE_HEAD for completion.
- Maps TD condition code to UsbError: 4=Stall, 5=NoDevice,
8=Babble, 0xF=Timeout, others=DataError.
- Computes actual bytes transferred correctly: hw_cbp==0
means full transfer; otherwise hw_cbp - buf_phys.
- For IN transfers, copies data out of the DMA buffer.
interrupt_transfer:
- Same TD/ED setup as bulk.
- Adds 'hcca' (Hcca pointer) and 'hcca_phys' fields to
OhciController for periodic ED placement.
- Places the ED in HCCA.int_table via periodic-slot selection.
Default slot 0 (period 1, every frame) for the synchronous
one-shot model. The 32-slot periodic table is walked by the
HC via the low 5 bits of the frame number.
- Enables PLE (Periodic List Enable) in HC_CONTROL.
- A 32-slot periodic table is implemented for proper OHCI
semantics (Linux-style balance() pattern: an ED with
interval N is inserted into every Nth slot).
- Per-interval slot selection picks the least-loaded branch for
the given interval.
- Polls HC_DONE_HEAD for completion; same error mapping.
- For IN transfers, copies data out of the DMA buffer.
registers.rs additions:
- CMD_CLF = 1<<1 (Control List Filled, for completeness)
- CMD_BLF = 1<<2 (Bulk List Filled)
- CTRL_PLE = 1<<2 (Periodic List Enable)
- TD_CC_* constants expanded for all 16 OHCI condition codes
(CRC, BitStuffing, DataToggleMismatch, Stall, DeviceNotResponding,
PIDCheckFailure, UnexpectedPID, DataOverrun, DataUnderrun,
BufferOverrun, BufferUnderrun, NotAccessed).
- TD_DP_IN/OUT direction bit constants.
- ED_DIR_IN/OUT direction bit constants.
- ED_LOW_SPEED constant.
- ED_MAX_PKT_SHIFT constant.
- HC_INTERRUPT_STATUS, HC_HCCA, HC_PERIOD_CURRENT_ED,
HC_PERIOD_HEAD_ED, HC_PERIOD_BANDWIDTH, HC_DONE_HEAD
address constants (for completeness).
- HCCA_ALIGN = 256 (OHCI spec: HCCA must be 256-byte aligned).
- HCCA_INT_TABLE_OFFSET = 0 (int_table is the first field of HCCA).
- NUM_INT_SLOTS = 32 (OHCI spec: 32 interrupt slots).
Pure-logic helpers extracted into standalone functions so they
can be tested on the host (redox-specific DMA/MMIO paths remain
in the methods that actually touch hardware):
- validate_data_endpoint(u8) -> Result<u8, UsbError>
- ed_direction_bits(TransferDirection) -> Result<u32, UsbError>
- build_data_ed_info(...)
- build_data_td_info(...)
- td_condition_code(hw_info)
- td_bytes_transferred(cbp, buf_phys, requested_len)
- td_cc_to_usb_error(cc)
- periodic_slot_for_interval(interval_ms)
- link_periodic_ed(ed_phys, hcca, interval)
Tests (15 new, all passing):
- validate_endpoint_accepts_numbered_endpoints
- validate_endpoint_rejects_control_and_bogus
- ed_direction_maps_out_and_in
- ed_direction_rejects_setup
- build_ed_info_packs_fields
- build_td_info_uses_carry_toggle_and_round
- build_td_info_out_direction
- cc_mapping_matches_linux_ohci
- td_condition_code_extract_is_correct
- bytes_transferred_full_completion
- bytes_transferred_short_read
- interrupt_slots_period_one_visits_every_frame
- (3 more for periodic slot selection)
Cross-reference to Linux 7.1 ohci-hcd.c:
- td_fill() pattern (TD_T_TOGGLE | TD_CC | TD_DP_IN/OUT)
- BLF (Bulk List Filled) kick via HcCommandStatus
- PLE (Periodic List Enable) for interrupt transfer
- balance() periodic-slot selection
- HC_DONE_HEAD polling pattern
Per local/AGENTS.md:
- No new branches (work on 0.3.1)
- No stubs, no todo!/unimplemented!
- Cat 1 in-house recipe - source IS the durable location
- No new warnings (verified: same warning count as HEAD)
Closes C1 from v4.8 audit. The single CRITICAL gap from the
round-2 scan is now fixed.
kellito
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