Wi-Fi hardware-timestamping prototypes: USB RX SO_TIMESTAMPING + PCIe PHC/rtw88#232
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… PHC/rtw88 Out-of-band reference tooling behind the timing findings in docs/timing-accuracy.md. None of it is part of the devourer library build. USB (surfaces the vendor rtl88x2cu RX hardware timestamp): - Bump the reference/rtl88x2cu submodule to the merged CONFIG_RTW_HWTSTAMP driver (attaches the RX-descriptor TSF to skb_hwtstamps -> SO_TIMESTAMPING). - tests/rx_hwtstamp_probe.c: AF_PACKET + SO_TIMESTAMPING reader. - tests/rx_hwtstamp_validate.sh: capability check (driver swap + ethtool -T). - tests/rx_hwtstamp_onair.sh: on-air value check against a devourer open AP. PCIe (RTL8821CE, rtw88): - tests/pcie_phc/: a passive PTP hardware clock off the MAC TSF over BAR2 MMIO (rtw88 stays bound), a gettime-latency probe, an Intel-I226 cross-check, and a one-hunk rtw88 RX skb_hwtstamps patch. See tests/pcie_phc/README.md. - tests/pcie_tsf_read.c: userspace BAR2 TSF reader. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Out-of-band reference tooling behind the timing findings in
docs/timing-accuracy.md. None of it is part of the devourer library build — it's kernel-side experiments intests/, so the library CI is unchanged.USB — surface the vendor
rtl88x2cuRX hardware timestampreference/rtl88x2cu→ the mergedCONFIG_RTW_HWTSTAMPdriver (attaches the RX-descriptor TSF toskb_hwtstampsbefore delivery, so aSO_TIMESTAMPINGsocket reads the 802.11 hardware RX timestamp).tests/rx_hwtstamp_probe.c— AF_PACKET +SO_TIMESTAMPINGreader.tests/rx_hwtstamp_validate.sh— capability check (driver swap +ethtool -T).tests/rx_hwtstamp_onair.sh— on-air value check against a devourer open AP; verified the RX timestamps advance in step with real airtime.PCIe — RTL8821CE (
rtw88)tests/pcie_phc/— a passive PTP hardware clock (/dev/ptpN) off the MAC TSF over BAR2 MMIO (rtw88stays bound; the module onlyioremaps and reads), a gettime-latency probe (~3.7 µs MMIO floor), an Intel I226 cross-check (Wi-Fi TSF tracks a real IEEE-1588 clock to ~290 ns), and a one-hunkrtw88RXskb_hwtstampspatch. Seetests/pcie_phc/README.md.tests/pcie_tsf_read.c— userspace BAR2 TSF reader.Scope
RX hardware timestamping works on both transports; a real PHC is tractable on PCIe. Two-way
ptp4lover the Wi-Fi radio stays blocked on a host-reported TX-egress timestamp (firmware limitation) — the board's I226 Ethernet is the real-PTP reference. All measured results and that limit are indocs/timing-accuracy.md.🤖 Generated with Claude Code