bfe-core1106-sdk/kernel/docs/bringup.md

RV1106 → Linux 6.18 forward-port (self-built, from vendor 5.10)

Decision ([maintainer], 2026-08-23): forward-port the RV1106 SoC enablement from the Rockchip vendor 5.10 tree straight to Linux 6.18 LTS, ourselves, using no plan44 code, built on our Buildroot 2025.02 LTS + uClibc. We own the tree.

The reality this rests on (verified, not assumed)

Vanilla mainline (6.6.93 and 6.18) has zero RV1106 support — no devicetree, no clock driver, no pinctrl data, not one rv1106 reference in arch/arm or drivers/. So "the newest kernel" is a generic ARM kernel that cannot boot this SoC. What we forward-port is the entire RV1106 BSP: ~120 files in the vendor 5.10 tree touch rv1106 (DT, clk, pinctrl, mach/PM, VOP display, mmc, and the out-of-tree AIC8800/RGA/MPP). This is a large, multi-milestone kernel effort; it is delivered incrementally, console-first.

Method (how each piece is ported)

• Framework drivers → sibling-delta. clk and pinctrl are driven by the shared rockchip framework (drivers/clk/rockchip/clk.c, pinctrl-rockchip.c). RV1106's siblings rv1126 and rv1108 exist in BOTH vendor-5.10 and mainline-6.18, so their 5.10→6.18 delta is the exact recipe for how the framework API changed — we apply that recipe to rv1106's data (clk-rv1106.c = 1284 lines; rv1106-cru.h clock IDs; the rv1106 pinctrl table). This turns "adapt to APIs we have to guess" into "copy a diff a sibling already proves."
• SoC-unique code → forward-port + build-fix-build. mach-rockchip (machine, rockchip_hptimer, rv1106_pm/rv1106_sleep.S), the CRU/GRF glue, and the board DT have no sibling; port directly and iterate on the 6.18 build.
• Mainline-present drivers → just wire DT + clocks. 8250-dw UART, dw_mmc (SDIO/eMMC), dw-apb i2c, rockchip gpio/pinctrl core, pwm, dw-wdt watchdog are all in mainline 6.18 — we do not port them, we supply the DT nodes + clock/reset phandles and let the mainline drivers bind.
• Out-of-tree drivers → port the driver. AIC8800 wifi (plan44 has none; ours), RGA/MPP kernel bits (assess vs need — the 86-Panel has no camera), carrying our Tier-1 SDIO-wakeup fix forward.
• Our 4 kernel patches (panel-mcu-reset/logo, watchdog-enable, usb-otg dual-role, recovery-splash) → re-apply against 6.18 (line offsets + some DT bindings changed).

Bring-up milestones (console-first order)

• M0 — buildable base. 6.18.46 tree + our Buildroot/uClibc toolchain builds a generic ARM kernel; a rv1106_defconfig forward-ported from vendor 5.10.
• M1 — SoC compiles. mach-rockchip RV1106 select + clk-rv1106 + rv1106 pinctrl data + rv1106-cru.h compile clean against 6.18 (no boot yet).
• M2 — earlycon boot. DT (rv1106.dtsi core) + clk + pinctrl + 8250-dw → kernel prints to the RV1106 UART. The first "it's alive."
• M3 — rootfs boot. dw_mmc + DT → eMMC/SD rootfs, userspace up on our Buildroot.
• M4 — display. VOP2 + the RGB666 720×720 panel + GT911 touch + PWM backlight → the LVGL UI renders.
• M5 — wifi + our patches. AIC8800 SDIO driver ported (+ Tier-1 fix); the 4 custom kernel patches re-applied.
• M6 — the rest. RGA (UI accel), watchdog, HPMCU coprocessor, USB-OTG dual role.

Regression (so a 6.18 port doesn't reintroduce the struct-ABI bug class)

The warden-sdk simulator + MC/DC harness are how we hold the line: HpmcuSim and the register/MemBus seam test the supervisor/reset logic off the ported kernel; the relays-mcdc pattern extends to each ported driver we own; and a config-lint CI gate (the class that bricked c8a3 — a load address in unreserved kernel RAM) checks the DT reservations against the drivers on every build.

Layout (this repo)

kernel/
  rv1106-enablement/   the ported RV1106 BSP as it lands (patches/files on 6.18)
  docs/bringup.md      this plan

The 6.18.46 source + the vendor 5.10 tree stay in flare-edge/research/ and flare-edge/.../sdk/ respectively (references, not committed here).