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.
2.3 KiB
NPU (rknpu) open kernel driver: VERIFIED on warden-c8a3 (2026-08-25)
The open GPL rknpu kernel driver runs on our self-built Linux 6.18.46. This is the
achievable open end state (Tier A in OPEN-NPU-PLAN.md); open compute remains a
from-scratch RE project (see the ceiling note below).
Evidence (serial, _b slot = our 6.18)
[drm] Initialized rknpu 0.9.2 for ff660000.npu on minor 1
/dev/dri/ -> card0 (VOP display) card1 (rknpu) renderD128
$ rknpu_version_test
/dev/dri/card0: not an rknpu node (version ioctl: Invalid argument)
opened /dev/dri/card1 (fd=3)
driver version: 0.9.2 (raw code 902)
hw version: 0x54524548 (raw)
PASS: /dev/dri/card1 answered both version-query ioctls -- probe,
power-get/put, and clock/reset all exercised.
The RKNPU_GET_DRV_VERSION/RKNPU_GET_HW_VERSION ioctls exercise the full
dispatch -> power-domain get/put -> clock/reset path, so a clean answer confirms the
whole driver bring-up, not just registration.
The fix that took it from probe-fail to PASS
The base dtsi npu@ff660000 node declares its interrupt but has no
interrupt-names; the rknpu driver requests its IRQ by name ("npu_irq"), so
probe bailed error -ENXIO: IRQ npu_irq not found and never registered its DRM
device. Board DTS override adds interrupt-names = "npu_irq"; (+ status="okay").
(The rest of the port (GPL source, 4 compat-shim headers for dead-code vendor
headers, 10 mechanical 6.18 API deltas) is in PORT-PROGRESS.md.)
Also: the version test must iterate DRM cards and keep the one that ANSWERS the
ioctl. The display card (card0) opens fine but returns EINVAL. Fixed in
rknpu_version_test.c.
The honest ceiling (why "100% open NPU" stops at the driver)
The kernel driver only DMAs an opaque userspace-authored regcmd blob into the PC
registers and pulses go. It never inspects the compute stream. The compute-engine
register map (TRM Part 2) is not public for RV1106, there is zero open RE prior
art for this NPU generation, and only the closed RKNN-Toolkit2 compiler emits
valid regcmd. Mainline accel/rocket + Mesa Teflon are RK3588-only (64-bit). So an
open compiler/runtime is a from-scratch, ~person-year register-RE project, scoped
(not staffed) in OPEN-NPU-PLAN.md (M-NPU-2 spike / M-NPU-3). We ship the open
driver; we do NOT ship any closed blob.