BFE Engineering
42fb386f60
Replace every em dash with real punctuation (rewrites, not hyphen swaps) in docs, code comments, scripts, configs, and the port records; convert en dashes, curly quotes, ellipsis glyphs, arrows, and section signs to ASCII; drop machine-writing tell phrases from living docs. ADR titles now use a colon. The M2 bring-up DTS model string carried an em dash into the patch series and its record echoes; fixed at both, and the full series re-verified to apply cleanly onto pristine 6.18.46. One comment in freshness.h deliberately names the em dash glyph the UI renders as the unknown mark; that is data, kept as prose naming it. Verified: cargo tests (sim, config-lint, rs485-bridge), shellcheck, both driver MC/DC harnesses, patches-apply.
44 lines
2.3 KiB
Markdown
44 lines
2.3 KiB
Markdown
# NPU (rknpu) open kernel driver: VERIFIED on warden-c8a3 (2026-08-25)
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The open GPL rknpu kernel driver runs on our self-built Linux 6.18.46. This is the
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achievable open end state (Tier A in `OPEN-NPU-PLAN.md`); open *compute* remains a
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from-scratch RE project (see the ceiling note below).
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## Evidence (serial, _b slot = our 6.18)
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```
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[drm] Initialized rknpu 0.9.2 for ff660000.npu on minor 1
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/dev/dri/ -> card0 (VOP display) card1 (rknpu) renderD128
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$ rknpu_version_test
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/dev/dri/card0: not an rknpu node (version ioctl: Invalid argument)
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opened /dev/dri/card1 (fd=3)
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driver version: 0.9.2 (raw code 902)
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hw version: 0x54524548 (raw)
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PASS: /dev/dri/card1 answered both version-query ioctls -- probe,
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power-get/put, and clock/reset all exercised.
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```
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The `RKNPU_GET_DRV_VERSION`/`RKNPU_GET_HW_VERSION` ioctls exercise the full
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dispatch -> power-domain get/put -> clock/reset path, so a clean answer confirms the
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whole driver bring-up, not just registration.
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## The fix that took it from probe-fail to PASS
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The base dtsi `npu@ff660000` node declares its interrupt but has **no
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`interrupt-names`**; the rknpu driver requests its IRQ by name (`"npu_irq"`), so
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probe bailed `error -ENXIO: IRQ npu_irq not found` and never registered its DRM
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device. Board DTS override adds `interrupt-names = "npu_irq";` (+ `status="okay"`).
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(The rest of the port (GPL source, 4 compat-shim headers for dead-code vendor
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headers, 10 mechanical 6.18 API deltas) is in `PORT-PROGRESS.md`.)
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Also: the version test must iterate DRM cards and keep the one that ANSWERS the
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ioctl. The display card (card0) opens fine but returns EINVAL. Fixed in
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`rknpu_version_test.c`.
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## The honest ceiling (why "100% open NPU" stops at the driver)
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The kernel driver only DMAs an opaque userspace-authored `regcmd` blob into the PC
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registers and pulses go. It never inspects the compute stream. The compute-engine
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register map (TRM Part 2) is not public for RV1106, there is **zero open RE prior
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art** for this NPU generation, and only the closed RKNN-Toolkit2 compiler emits
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valid regcmd. Mainline `accel/rocket` + Mesa Teflon are RK3588-only (64-bit). So an
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open compiler/runtime is a from-scratch, ~person-year register-RE project, scoped
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(not staffed) in `OPEN-NPU-PLAN.md` (M-NPU-2 spike / M-NPU-3). We ship the open
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driver; we do NOT ship any closed blob.
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