Crate culvert 

Typed access to the HDMI 2.1 SCDC (Status and Control Data Channel) register map.

Culvert sits on top of hdmi_hal::scdc::ScdcTransport and provides named structs, bitfield types, and typed operations for scrambling control, FRL training primitives, and CED (Character Error Detection) reporting.

The central type is Scdc, a thin stateless client that wraps a transport and exposes one typed method per register group. Sequencing of register operations — rate selection, timeout handling, retry logic — belongs in the link training crate above.

The register map itself — addresses and per-register encoding and decoding — is the I/O-free codec module, which Scdc and culvert-async’s client share.

Modules

codec

Register addresses and per-register encoding and decoding for the SCDC register map (HDMI 2.1), without I/O.

Structs

CedCount

A 15-bit character error count decoded from an ERR_DET register pair.

CedCounters

Per-lane character error counts decoded from ERR_DET registers (0x50–0x55 for lanes 0–2, 0x57–0x58 for lane 3).

CedReading

The per-lane character error counts from one read of the CED registers, with what the read found wrong.

ClearableUpdateFlags

The Update_0 flags a source may clear: every flag but RR_Test (bit 2).

Config0

Content written to Config_0 (0x30).

FfeLevels

FFE (Feed-Forward Equalization) levels written into Config_1 bits[7:4]: the highest TxFFE level index the source supports for the requested rate.

FrlConfig

Configuration written to Config_1 (0x31). Build one with new.

LtpRequests

Per-lane link training pattern requests from Status_Flags_1 (0x41) and Status_Flags_2 (0x42).

RsCorrectionCount

A 15-bit Reed-Solomon correction count decoded from RS_Correction_L/H (0x59/0x5A).

Scdc

Typed client for the HDMI 2.1 SCDC (Status and Control Data Channel) register map.

ScramblerStatus

Decoded content of Scrambler_Status (0x21).

SourceTestConfig

Decoded content of Source_Test_Configuration (0x35).

StatusFlags

Decoded content of Status_Flags_0 (0x40).

TmdsConfig

Configuration written to TMDS_Config (0x20).

UpdateFlags

Decoded content of Update_0 (0x10).

Enums

CedWarning

A non-fatal anomaly in a CED read, returned with the decoded counters in CedReading.

FrlRate

Maximum Fixed Rate Link (FRL) bandwidth supported by a HDMI 2.1 sink.

HdmiLanes

The link’s data lanes, re-exported from display-types: three for TMDS and 3-lane FRL, four for 4-lane FRL (FrlRate::lanes). Scdc::read_ced takes it to know what the CED checksum covers: 0x50–0x56 with Three, 0x50–0x58 with Four. The number of data lanes an HDMI link carries: three for TMDS (its three data channels) and 3-lane FRL, four for 4-lane FRL, where the TMDS clock channel becomes lane 3. See HdmiForumFrl::lanes.

LtpReq

Link Training Pattern requested by the sink for one lane: a 4-bit field in Status_Flags_1 (0x41, lanes 0–1) or Status_Flags_2 (0x42, lanes 2–3).

ProtocolError

What culvert refuses because it would violate the SCDC protocol.

ScdcError

Errors returned by Scdc register operations.

Traits

ScdcTransport

The transport Scdc<T> is generic over, re-exported from hdmi-hal. Raw register access to the SCDC register map over DDC/I²C.