Transcribe BCM PDFs to markdown visually (tables intact); catalog probe candidates: EEE advertised in reference bringup, EMI cmds are fast-retrain enables, 1588/loopback/ECD chapters missing

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 # BCM84891L MDIO command handler — transcription
 Transcribed (visually, tables intact) from the FS-provided excerpt of the Broadcom
 datasheet `84891L-DS101` (`BCM84891L-MDIO Command Descriptions-.pdf`). The excerpt
 keeps the cover, TOC, and datasheet pages 41–59. Chapters the TOC lists but the
 excerpt **omits** — each a potential follow-up ask to FS:
 - §1.17 EEE / AutogrEEEn (enable/disable, **monitoring EEE readiness**, fast retrain
  modes: IEEE FR, Negotiated FR, BCM-proprietary FR)
 - §1.18 Jumbo packets, §1.19 HiGig2
 - §1.20 Loopback operation — per-speed PCS loopbacks and **copper line loopback at
  PMD/PCS** (§1.20.2)
 - §1.21 Management interface, §1.22 TRD (MDI) pair swapping, §1.23 SPI
 - **Chapter 2: Register Summary** (p62+)
 - Not in the TOC at all: the ECD chapter and the 1588 operation chapter.
 Device headline features (cover page): IEEE 1588-2008 v2-compliant; IEEE fast retrain
 and link monitoring; EEE with AutogrEEEn; enhanced cable diagnostics; detection and
 correction of pair swaps (MDI crossover), pair skew, and pair polarity; line-side
 loopback; jumbo to 18 KB; low-EMI; XFI/USXGMII/KR host interfaces.
 ## Handler protocol (§1.24)
 Write the command code to CMD `1E.0x4005` with bit 15 set; firmware raises an
 interrupt, services the command, and reports through STATUS `1E.0x4037`
 (bidirectional — user-writable). Poll STATUS every ~100 ms. During the 2-second
 10GBASE-T training phase STATUS freezes (returns SYSTEM_BUSY); only issue commands
 after link-up.
 | Register | Address |
 |---|---|
 | CMD | 1E.0x4005 |
 | STATUS | 1E.0x4037 |
 | DATA1–DATA5 | 1E.0x4038–1E.0x403C |
 | STATUS code | Value |
 |---|---|
 | CMD_RECEIVED | 0x0001 |
 | CMD_IN_PROGRESS | 0x0002 |
 | CMD_COMPLETE_PASS / OPEN_FOR_CMDS | 0x0004 |
 | CMD_COMPLETE_ERROR / OPEN_FOR_CMDS | 0x0008 |
 | CMD_SYSTEM_BUSY | 0xBBBB |
 Procedure: poll STATUS until neither IN_PROGRESS nor BUSY → write params to DATAn →
 write code\|0x8000 to CMD → poll STATUS for PASS/ERROR → read DATAn results.
 Provisioning changes generally require an AN restart to take effect.
 **Field note (hardware-verified):** the handler does not clear DATA registers it
 doesn't use — stale values persist across commands. GET_SNR must be invoked with
 *no* DATA1 write (see its entry).
 ## Table 5 — command codes (verified against hardware)
 | Command | Code | Notes |
 |---|---|---|
 | CMD_GET_PAIR_SWAP | 0x8000 | |
 | CMD_SET_PAIR_SWAP | 0x8001 | needs AN restart |
 | Reserved | 0x8002, 0x8003 | |
 | CMD_GET_1588_ENABLE | 0x8004 | |
 | CMD_SET_1588_ENABLE | 0x8005 | needs AN restart |
 | GET_LIMITED_REACH_MODE_ENABLE | 0x8006 | |
 | SET_LIMITED_REACH_MODE_ENABLE | 0x8007 | |
 | CMD_GET_EEE_MODE | 0x8008 | |
 | CMD_SET_EEE_MODE | 0x8009 | needs AN restart |
 | CMD_GET_EMI_MODE_ENABLE | 0x800A | **description says: gets SW fast-retrain enable** |
 | CMD_SET_EMI_MODE_ENABLE | 0x800B | **sets fast-retrain enables; needs AN restart** |
 | CMD_GET_SUB_LF_RF_STATUS | 0x800D | |
 | GET_KR_MODE_ENABLE | 0x800E | |
 | SET_KR_MODE_ENABLE | 0x800F | |
 | CMD_CLEAR_SUB_LF_RF | 0x8010 | |
 | CMD_SET_SUB_LF_RF | 0x8011 | |
 | GET_SYNC_E_ENABLE | 0x8012 | |
 | SET_SYNC_E_ENABLE | 0x8013 | |
 | GET_XFI_2P5G_5G_MODE | 0x8016 | |
 | SET_XFI_2P5G_5G_MODE | 0x8017 | |
 | SET_EEE_STATISTICS | 0x801A | arm counters; issue after link-up |
 | GET_EEE_STATISTICS | 0x801B | |
 | GET_JUMBO_PACKET | 0x801D | note: GET is 1D |
 | SET_JUMBO_PACKET | 0x801C | note: SET is 1C |
 | GET_PAUSE_FRAME_MODE | 0x801F | WAP/idle-stuffing niche only |
 | SET_PAUSE_FRAME_MODE | 0x8020 | WAP/idle-stuffing niche only |
 | GET_LED_TYPE | 0x8021 | |
 | SET_LED_TYPE | 0x8022 | |
 | GET_WAP_MODE_FRAME_TYPE | 0x8023 | |
 | SET_WAP_MODE_FRAME_TYPE | 0x8024 | |
 | SET_USXGMII | 0x8026 | |
 | GET_USXGMII | 0x8027 | |
 | GET_XFI_TX_FILTERS | 0x802B | |
 | SET_XFI_TX_FILTERS | 0x802C | |
 | GET_XFI_POLARITY | 0x802D | |
 | SET_XFI_POLARITY | 0x802E | |
 | GET_CURRENT_VOLTAGE | 0x802F | |
 | CMD_GET_SNR | 0x8030 | |
 | CMD_GET_CURRENT_TEMP | 0x8031 | |
 | CMD_SET_UPPER_TEMP_WARNING_LEVEL | 0x8032 | |
 | CMD_GET_UPPER_TEMP_WARNING_LEVEL | 0x8033 | |
 | CMD_SET_LOWER_TEMP_WARNING_LEVEL | 0x8034 | |
 | CMD_GET_LOWER_TEMP_WARNING_LEVEL | 0x8035 | |
 | SET_WOL_ENABLE | 0x805A | |
 | GET_WOL_ENABLE | 0x805B | |
 ## Command semantics
 ### CMD_GET_PAIR_SWAP (0x8000) / CMD_SET_PAIR_SWAP (0x8001)
 GET: DATA1 = forced/requested swap value, DATA2 = current swap value.
 SET: DATA2 = value to force; needs AN restart.
 Encoding (Table 8): bits [7:6] PAIR_D_SEL, [5:4] PAIR_C_SEL, [3:2] PAIR_B_SEL,
 [1:0] PAIR_A_SEL; each 2-bit field: 00=Pair A, 01=B, 10=C, 11=D.
 ### CMD_GET/SET_1588_ENABLE (0x8004/0x8005)
 DATA1: 0 = IEEE 1588 disabled, 1 = enabled. Set prior to link-up (or bounce the
 link via AN restart). The 1588 engine's own registers are not documented in this
 excerpt.
 ### GET/SET_LIMITED_REACH_MODE_ENABLE (0x8006/0x8007)
 DATA1: 0 = LR mode disabled, 1 = enabled.
 DATA2 (when enabled): 0 = dynamically switch to LR power-saving level 2 **based on
 cable length**; 1/2/3 = forced level 1 (most saving) / 2 / 3 (least).
 GET-only DATA3: 1 = currently linked in limited-reach mode — the sole
 handler-visible consequence of the DSP's internal length estimate.
 ### CMD_GET_EEE_MODE (0x8008) / CMD_SET_EEE_MODE (0x8009)
 Per-speed EEE mode fields in DATA1 — 10G in bits [1:0], 1G/100M in [3:2]
 (interpreted per bits [11:10]), 2.5G in [5:4], 5G in [7:6]:
 0 = EEE disabled, 1 = native EEE, 2 = AutogrEEEn fixed latency,
 3 = AutogrEEEn variable latency.
 DATA2 = AutogrEEEn high threshold, DATA3 = low threshold (default 0x7A12),
 DATA4 = AutogrEEEn latency (default 0x480); shared across 2.5/5/10G, ignored at 10G
 native. SET needs AN restart.
 ### CMD_GET/SET_EMI_MODE_ENABLE (0x800A/0x800B)
 Datasheet titles say EMI; both descriptions read "SW Fast Retrain enable":
 DATA1 = 10G fast retrain (0/1), DATA2 = 5G, DATA3 = 2.5G. SET needs AN restart.
 ### CMD_GET_SUB_LF_RF_STATUS (0x800D), CLEAR (0x8010), SET (0x8011)
 Substitution of local/remote fault codes with IDLE toward the line direction.
 GET DATA1: 0 = copper-TX LF/RF passes through, 1 = LF/RF replaced with IDLE.
 SET enables substitution, CLEAR disables it.
 ### GET/SET_KR_MODE_ENABLE (0x800E/0x800F)
 DATA1: KR mode on the host interface, 0/1. (KR unsupported when 2500X/5000X mode
 is enabled.)
 ### GET/SET_SYNC_E_ENABLE (0x8012/0x8013)
 DATA1 SyncE enable; DATA2/DATA3 M0/M1 recovered-clock mux select (P0 10G, P1–P3
 10G/1G, or P0 1G); DATA4 FW-vs-user control; DATA5 bits [1:0] M0/M1 output
 disable.
 ### GET/SET_XFI_2P5G_5G_MODE (0x8016/0x8017)
 Rate adaptation for 2.5G/5G on the host side: 0 = 10G idle-stuffing, 1 = X mode,
 2 = R mode (per speed in DATA1/DATA2).
 ### SET_EEE_STATISTICS (0x801A) / GET_EEE_STATISTICS (0x801B)
 SET arms the statistics (no params; issue after link-up). GET input selector:
 0 = event counters, 1 = time durations. Returns TX(LOC) counter/time in
 DATA2 (low 16) / DATA3 (high 16) and RX(REM) in DATA4/DATA5. PHY picks the
 10G or 1G counter bank from current link speed.
 ### GET/SET_JUMBO_PACKET (0x801D/0x801C)
 DATA1 enable; DATA2 size option 0 = 10K, 1 = 18K, 2 = 9K.
 ### GET/SET_PAUSE_FRAME_MODE (0x801F/0x8020)
 DATA1: 0 = no pause frame, 1 = enabled. **Only valid for 2.5/5G idle-stuffing in
 10G XFI WAP mode** — inert in plain 10G operation.
 ### GET/SET_LED_TYPE (0x8021/0x8022)
 DATA1: 0 = firmware control, 1 = user control.
 ### GET/SET_WAP_MODE_FRAME_TYPE (0x8023/0x8024)
 GET: DATA1 = 1 when priority protocol is IEEE 802.3bz; DATA2 current link frame
 type (1 = 802.3bz, 2 = NBASE-T). SET: DATA1 frame-type priority.
 ### SET/GET_USXGMII (0x8026/0x8027)
 DATA1 enable; DATA2 USXGMII autoneg; DATA3 [2:0] single_max_speed (1 = 2.5G,
 2 = 5G, 4 = 10G); DATA5: 1 = MAC/PHY frequency unlocked, 0 = locked.
 ### GET/SET_XFI_TX_FILTERS (0x802B/0x802C)
 Host-side XFI TX FIR taps. GET (for the current link speed; invalid if link
 down): DATA2 [7:0] pre tap / [15:8] main tap; DATA3 [7:0] post1 / [15:8] post2;
 DATA4 [15:8] TX HPF. SET adds DATA1 [15:8] speed selector (0 = 10G
 backward-compat, 1 = 100BT, 2 = 1G, 3 = 10G, 4 = 2.5G, 5 = 5G).
 ### GET/SET_XFI_POLARITY (0x802D/0x802E)
 DATA2 TX polarity, DATA3 RX polarity.
 ### GET_CURRENT_VOLTAGE (0x802F)
 DATA1/DATA2 = 0.8 V rail measurements, DATA3 = 1.88 V rail. (Observed: tenths of
 mV — 0x1E47 ≈ 775.1 mV, 0x49BC ≈ 1887.6 mV.)
 ### CMD_GET_SNR (0x8030)
 Documented: DATA1 input 0/1 = display SNR in IEEE registers; returns DATA2–5 =
 SNR for channels A–D in dB×10. **Hardware-verified behavior: write nothing to
 DATA1** — writing the display flag (either value) makes this firmware return
 zeros, and the IEEE registers 1.133–1.140 never populate (constant 0x8080)
 regardless. Bare invocation returns live per-pair SNR (~27–32 dB on a bench
 cable, 0.1–0.4 dB jitter per read). Values are absolute receiver SNR.
 ### CMD_GET_CURRENT_TEMP (0x8031)
 DATA1 = die temperature (°C; observed ~68–70 on bench).
 ### Temp warning levels (0x8032–0x8035)
 Upper/lower limit in °C (two's complement) in DATA1, margin in DATA2, enable in
 DATA3.
 ### SET/GET_WOL_ENABLE (0x805A/0x805B)
 DATA1: 0/1. SET takes effect immediately; soft-reset the PHY afterward. Only
 relevant at 2.5G and above.
 ## LED programmability (§1.26)
 LED control words live in top-level vendor registers **1.0xA83B (LED Control)**
 and **1.0xA83C (LED Control Source)** — five programmable LEDs, per-LED source
 masks, 2-bit mode fields (off / blink-on-source / on-on-source), activity
 sources: bit 1 RX activity, bit 2 TX activity, with a stretch enable for
 visibility. (First documented vendor registers outside the handler; the SMI
 example in the registers reference writes another one, 1.0xA820.)
@@ -0,0 +1,79 @@
 # FS SFP-10G-T-100 transport reference — transcription
 Transcribed (visually, tables intact) from the FS-provided 4-page
 `10GBase-T Coper SFP Registers Operation's Reference for BCM84891.pdf`
 (an ODM document — PDF metadata titles it "ABCU-5710RZ / ABCU-5700RZ").
 ## 1. Serial ID memory (A0h)
 Standard SFP MSA serial ID at I2C A0h. Notable factory values (the module is
 honest about copper — cf. hardware.md):
 | Addr | Field | Value | Meaning |
 |---|---|---|---|
 | 0 | Identifier | 03 | SFP |
 | 1 | Ext. identifier | 04 | MOD4 |
 | 2 | Connector | 21 | Copper pigtail (the shipped unit reads 22 = RJ45) |
 | 3–10 | Transceiver | 02 00 00 00 00 08 00 00 | 10G Base-XFI to copper / SGMII to copper |
 | 11 | Encoding | 00 | 64B/66B (or 8B/10B) |
 | 12 | BR, nominal | 67 | 10.3125 GBd |
 | 18 | Length (copper) | 64 | 100 m; 30 m minimum in-spec copper length |
 | 20–35 | Vendor name | "OEM " | shipped unit reads "FS" |
 | 40–55 | Vendor PN | "10GBase-T C100m" | shipped unit reads "SFP-10G-T-100" |
 | 64–65 | Options | 00 12 | TX_DISABLE and RX_LOS implemented (shipped: 00 1A) |
 | 92 | Diag monitoring | 00 | **no A2h DOM implemented** |
 | 93 | Enhanced options | 00 | |
 | 94 | SFF-8472 compliance | 00 | digital diagnostics not included |
 | 96–127 | Vendor specific | all 00 | |
 ## 2–3. SMI (I2C→MDIO) protocol for the PHY, with timing
 The PHY is a 2-wire device at 8-bit address **0xAC write / 0xAD read**
 (`1010110x`). Clause-45 access frames:
 **Write (one I2C frame, 6 bytes):**
 `S [0xAC] [000+DEVAD] [Reg_H] [Reg_L] [Data_H] [Data_L] P`
 **Read (two I2C frames):**
 `S [0xAC] [001+DEVAD] [Reg_H] [Reg_L] P` → **delay > 1 ms** →
 `S [0xAD] [Data_H] [Data_L] P`
 Bit-level example diagrams confirm: every byte is slave-ACKed except the final
 read data byte, which the master **NAKs** before STOP. Worked examples: write
 0x55AA to 1.0xA820; read 0x8542 from 1.0x0003.
 ## 4. PHY MMD map
 Clause-45 MMDs behind the bridge:
 | DEVAD | Block |
 |---|---|
 | 1 | 10GBASE-T PMA/PMD |
 | 3 | 10GBASE-T PCS; XFI_M (XGMII) block also on DEVAD 3 |
 | 7 | AN; SGMII block and 10/100/1000BASE-T PCS/PMA/PMD at 7.0xFFE0–0xFFFF |
 | 30 | Top level (user-defined) |
 Side blocks: JTAG, SPI, BSC, PLL/clock, LED controller.
 ## 5. Reference access commands and 10G bring-up sequence
 The ODM's host-side primitives are exactly our `sff_i2c` ops:
 `Write_XGPHY_Register 0xAC [000+DEVAD] RegH RegL DataH DataL` and
 `Read_XGPHY_Register 0xAC [001+DEVAD] RegH RegL, >1 ms, 0xAD DataH DataL`.
 Reference sequence "set PHY to work in 10GBE rate" (write in order):
 | Frame | Register = value | Meaning |
 |---|---|---|
 | AC 01 00 00 20 40 | 1.0 = 0x2040 | PMA control: 10G speed select |
 | AC 01 00 07 00 09 | 1.7 = 0x0009 | PMA control 2: 10GBASE-T type |
 | AC 07 00 10 10 01 | 7.16 = 0x1001 | AN advertisement |
 | AC 07 00 20 10 03 | 7.32 = 0x1003 | 10GBASE-T AN control |
 | AC 07 00 3C 00 08 | 7.60 = 0x0008 | **EEE advertisement — advertises 10GBASE-T EEE** |
 | AC 07 00 40 00 00 | 7.64 = 0x0000 | |
 | AC 07 80 00 00 10 | 7.0x8000 = 0x0010 | vendor AN register |
 | AC 07 00 00 B2 00 | 7.0 = 0xB200 | AN control: enable + restart |
 The EEE-advertisement line means the reference bring-up (and possibly the module
 firmware's own defaults) leaves 10GBASE-T EEE negotiable — verify and disable
 for measurement runs (see modules.md probe list).
@@ -34,13 +34,17 @@ All via the SMI bridge + command handler (transports.md carries the codes and th
 - **Standard PCS 3.32/3.33** — block lock, latched errored-block/BER counters, clear-on-read: the noise-stress error proxy.
 - **Retrain** — IEEE AN restart `7.0 |= bit9`, relinks in ~6 s.
-Documented in the handler table, not yet exercised:
+Documented in the handler table, not yet exercised (full transcription: `bcm84891l-mdio-commands.md`), in probe-priority order:
- **CMD_GET_PAIR_SWAP 0x8000** — MDI wiring/crossover/polarity report.
+- **GET_EEE_MODE 0x8008** — per-speed EEE mode (disabled / native / AutogrEEEn fixed / variable; 10G in DATA1 bits [1:0]). Probe first: the ODM's reference bring-up *advertises 10GBASE-T EEE* (`7.60 = 0x0008`, see `bcm84891l-sfp-registers.md`), and module-to-module LPI would corrupt loss and latency numbers. `SET_EEE_MODE 0x8009` can force it off (AN restart to apply).
 - **SET/GET_EEE_STATISTICS 0x801A/0x801B** — arm after link-up, then read TX(local)/RX(remote) LPI event counters or time durations. Direct evidence of whether EEE is actually happening on the wire, independent of what's advertised.
 - **Fast-retrain enables 0x800A/0x800B** — the datasheet titles these EMI_MODE but both descriptions read "SW Fast Retrain enable" (per-speed, DATA1=10G/DATA2=5G/DATA3=2.5G). Fast retrains mask marginal-cable events as sub-ms hiccups; knowing (and possibly controlling) the enable state matters when attributing loss bursts.
 - **CMD_GET_PAIR_SWAP 0x8000** — forced and current MDI pair mapping, 2 bits per pair: wiring/crossover verification.
 - **GET_LIMITED_REACH_MODE 0x8006** — DATA3 = "currently linked in limited-reach mode": the only handler-visible consequence of the DSP's internal cable-length estimate, a single short/long bit, and only meaningful when LR mode is enabled (a config change — measure-only by default).
- **GET_EEE_MODE 0x8008 / GET_EEE_STATISTICS 0x801B** — verify EEE is off before trusting loss numbers.
+- **GET_SUB_LF_RF_STATUS 0x800D** — whether copper-TX local/remote fault codes pass through or are replaced with IDLE toward the line (SET/CLEAR 0x8011/0x8010): affects whether the far end can see faults at all.
- **GET_SUB_LF_RF_STATUS 0x800D** — local/remote fault detail.
+- **Host-interface health**: GET_XFI_TX_FILTERS 0x802B (FIR taps for the current speed), GET_XFI_POLARITY 0x802D, GET_USXGMII 0x8027 (DATA5 = MAC/PHY frequency unlock flag).
 - Pause-frame mode (0x801F/0x8020) turns out to be scoped to 2.5/5G idle-stuffing under 10G XFI WAP mode — inert in plain 10G operation.
-**No cable length.** The handler catalog is complete (§1.25.1.1–45: pair swap through WOL) and contains no ECD, length, or skew command. Cable length, opens/shorts, pair skew, and polarity live in the separate ECD register mechanism whose chapter FS hasn't sent — still the one outstanding ask. Until it lands, FS-side length comes only from the NIC timestamp path — in contrast to the Aquantia oracle, whose `1E.C884` length register is fully documented.
+**No cable length.** The handler catalog is complete (§1.25.1.1–45: pair swap through WOL) and contains no ECD, length, or skew command. Cable length, opens/shorts, pair skew, and polarity live in the separate ECD register mechanism whose chapter FS hasn't sent. The 1588 engine is the same story: the PHY is IEEE 1588-2008 v2-compliant with a one-command enable (0x8004/0x8005) but its operation registers are undocumented — in-PHY timestamping would measure path delay at the MDI, taking PHY-pipeline latency out of the length equation entirely (open-questions.md §2). Until either chapter lands, FS-side length comes only from the NIC timestamp path — in contrast to the Aquantia oracle, whose `1E.C884` length register is fully documented.
 ## Marvell cable-length register candidates (unverified, single-shot only)
 From kernel drivers for sibling parts — templates for a *future* single targeted probe on a sacrificial module, never a sweep, never near `*.0x??64`:
@@ -53,10 +53,10 @@ Docs are in this folder (`10GBase-T...BCM84891.pdf` transport, `BCM84891L-MDIO C
  - **CMD_GET_SNR = 0x8030** — invoke with **no DATA1 write**; writing the documented display flag makes this firmware return zeros. Bare invocation returns DATA2–5 = per-pair SNR (channels A–D) in tenths of dB. Bench: 27–32 dB absolute, ~0.1–0.4 dB read-to-read jitter. This is *absolute* receiver SNR, not margin (10GBASE-T operating point ≈ 26.5 dB).
  - The IEEE PMA SNR registers 1.133–1.140 read a constant 0x8080 on the BCM — never populated, display flag inert. **On FS modules SNR comes from the command handler, not standard registers.**
  - **CMD_GET_CURRENT_TEMP = 0x8031** (die runs ~70 °C on bench), **GET_CURRENT_VOLTAGE = 0x802F**.
-  - **Trap: 0x8020 is SET_PAUSE_FRAME_MODE** — a config *write*, and the handler executes whatever stale DATA1 holds as its argument. Module pause is explicitly set to 0 (off — the state cabletest requires); GET_PAUSE_FRAME_MODE (0x801F) returns junk on this firmware, so treat the setting as write-only.
+  - **Trap: SET commands execute stale DATA1.** The handler doesn't clear DATA registers between commands, so invoking any SET without writing its params applies leftover garbage (0x8020 SET_PAUSE_FRAME_MODE was hit this way under the old wrong GET_SNR constant — harmlessly, since pause mode is scoped to 2.5/5G idle-stuffing under XFI WAP mode and is inert at plain 10G).
  - The >1 ms SMI read delay: 3 ms works reliably.
-  - Also pair swap/skew/polarity, 1588.
+  - Full command catalog with semantics: `bcm84891l-mdio-commands.md`. Probe-priority list: modules.md "What the FS/BCM gives".
-  - **Enhanced Cable Diagnostics** (shorts/opens/**cable length**) is a headline feature, but its invocation is NOT in the command-code table (0x8000–0x805B) — it's a separate ECD register mechanism whose chapter isn't in the docs FS sent. This is the one outstanding ask to FS.
+  - **Enhanced Cable Diagnostics** (shorts/opens/**cable length**) is a headline feature, but its invocation is NOT in the command-code table (0x8000–0x805B) — it's a separate ECD register mechanism whose chapter isn't in the docs FS sent. The FS ask list, in value order: the ECD chapter, the 1588 operation chapter (in-PHY timestamping; enable exists at 0x8004/5), datasheet §1.20 loopback (copper line loopback) and §1.17 EEE/fast-retrain monitoring, and Chapter 2 register summary — the excerpt's TOC names them all.
 **Correct BCM SMI framing over the E810 topo-I2C** (recorded in case a write-capable multi-byte transport reappears): read = write `[001+devad,RegH,RegL]` offset_size=1, STOP, >1 ms, then read 2 B offset_size=0; write = offset_size=2, addr = devad<<8|RegH, data = `[RegL,DataH,DataL]`.