The maintained line of this project is the aperto branch. main is kept as the original author's line; all current code, documentation and releases (tags vYYYY.MM.DD) live on aperto. Please base work and pull requests on aperto.

open-tx-isp

Open reimplementation of Ingenic's closed TX-ISP kernel driver (tx-isp-<soc>.ko) for T10, T20, T21, T23, T30, T31, T40 and T41. The goal is behavioural equivalence with the OEM driver: same ioctl and libimp ABI, same register sequencing, same image behaviour, with cleaner unload/reload, checked inputs and less memory.

It works with Ingenic's unmodified libimp.so and with the open replacement OpenIMP. Open stack = open-tx-isp + OpenIMP + a streamer (timps). The aperto branch carries the released open stack on top of the original main line; see Branches and releases.

This is a reverse-engineering and compatibility effort, not a greenfield pipeline: OEM binary analysis, libimp ABI work and recovery of tuning data.

Status

State on aperto (2026-10-04). "Fully open" = open driver, OpenIMP and streamer run from a flashed image.

SoC	Status
T10	Fully open; day/night, reload (5 cycles) and boot guard verified. Image controls partly documented. Module 731 KB.
T20	Fully open; 1 h 44 min soak without errors, 10x stop/start and reload without an oops, rmmod during streaming refused. Module 736 KB.
T21	First open bring-up, now fully open; AE/ADR/defog/AWB lifted from the vendor module. Module 452 KB (vendor 616).
T23	Fully open (native encoder in OpenIMP); module 622 KB (vendor 857); vendor AE default. Frequent Helix frame drops fixed (residual interrupt, kernel patch merged upstream); still open: a rare single Helix encode error (errno 5), no real WDR.
T30	Builds against a real T30 kernel; earlier bring-up on hardware. Not exercised in the latest campaign.
T31	Reference SoC; SC2336, GC2053, SC301IOT; 2 h 53 min soak without errors; module 711 KB (vendor 829).
T40	Device-tested earlier (T40XP/GC4653); statistics restart stability is a known limitation. Not in the latest campaign.
T41	Fully open from a flashed image (H.264, H.265); reload verified (10/10); module 80 KB smaller than before. Open: flip, night column noise.

Per feature and SoC: FEATURE_MATRIX. History: CHANGELOG.md.

Better than the vendor driver

• Reload and stop: 10 stop/start and rmmod/insmod cycles without an oops on T20/T21/T23/T31/T41 (T10: 5 cycles).
• T20/T10 give back about 8 MB RAM (unused 8 MiB V4L2 frame pool off by default); on a T20 the open stack measured 10.5 % streamer CPU against 25.2 % with the vendor stack, snapshots 0.20 s against 0.45 s.
• Smaller modules than the vendor on T21, T23 and T31.
• Checked inputs (all user copies, QBUF window, bounded waits), sensor module pinned while streaming.
• T21 controls and noise reduction act (the vendor ignores them), T10/T20 noise-reduction strength acts.
• Shortfall logging with a concrete parameter value when reserved memory is too small.

Details and streamer integration notes: OPENIMP_BEYOND_VENDOR.

Build

Out-of-tree kernel modules, built against a Thingino buildroot output (toolchain and vendor kernel tree, Linux 3.10.14 for T10-T31, 4.4.94 for T40/T41). The helper picks the SoC with SOC:

SOC=t31 ./build_local.sh          # t10 t20 t21 t23 t30 t31 t40 t41
TH=/path/to/thingino-firmware SOC=t23 ./build_local.sh

TH, ROOT, KDIR, CROSS and ARCH can be overridden (see the comments in build_local.sh). It builds driver/<soc>/ into tx-isp-<soc>.ko plus the diagnostic driver/tx_isp_trace.ko; when no module for the SoC was built locally the result is a compile baseline only. The T20 driver expects the external/ingenic-sdk submodule (git submodule update --init). Host tests for kernel-independent primitives: make -C tests check.

Integration in Thingino

The packages open-tx-isp (this driver) and openimp (userspace) are in the upstream thingino-firmware branch aperto (#1756), selected with BR2_PACKAGE_THINGINO_ISP_OPEN (menu "ISP stack") and pinned by commit SHA to the aperto branches of the opensensor repositories. The module is installed as tx-isp-<soc>.ko and replaces the proprietary one; SDK sensor, audio and AVPU modules stay. The kernel VPU/rmem stability patches (#1748, #1752) are merged there. The optional boot guard BR2_PACKAGE_THINGINO_ISP_GUARD (#1749, default off; isp_open=auto|manual|off) skips the ISP/sensor modules after an unstable load so a bad driver cannot boot-loop the camera. Once the first date tag exists on aperto, thingino's aperto branch will pin that tag instead of a SHA.

Branches and releases

• main: the original author's line (opensensor). It is left untouched and is a strict ancestor of aperto.
• aperto: the open stack release line: OpenIMP + open-tx-isp, as used by the thingino aperto branch. Fast-forward only; every commit was flashed and checked on cameras. Releases are tagged vYYYY.MM.DD on this branch, and thingino pins a tag instead of a SHA.
• Development and the device-test campaign happen in the Lu-Fi forks (branch next = integration, claude/<topic> = topic branches); tested work reaches aperto from next after a clean soak.
• Companion repository: opensensor/openimp (branch aperto). Both repositories are released together; use matching tags.

Documentation

• Wiki (one wiki for both repositories): module parameters, memory (rmem, ispmem, MMAP pool), troubleshooting, install and boot guard, release scheme.
• docs/T31_ISP_ARCHITECTURE.md: hardware and driver architecture
• docs/ISP_SOC_ALGORITHM_VARIANCE.md: algorithm differences between SoCs
• docs/DRIVER_REUSE_PLAN.md, docs/SHARED_DRIVER_LIBRARY.md: shared code
• docs/IMAGE_TUNING_PRD.md: image tuning plan
• docs/ISP_PERFORMANCE_BENCHMARK.md: on-device CPU/memory baseline
• docs/V4L2_CAPTURE_PATH.md: V4L2 capture architecture
• docs/INTERRUPT_DEBUG_GUIDE.md: interrupt debugging
• docs/re/: reverse-engineering dumps (T31 vendor module HLIL)
• Per SoC: driver/t10/README.md, driver/t20/README.md, driver/t21/README.md (+ COMPARATIVE_ANALYSIS.md), driver/t23/README.md, driver/t30/README.md, driver/t31/README.md, driver/t40/README.md, driver/t41/README.md

Layout: driver/<soc>/ per-SoC driver, driver/common/ and driver/include/tx_isp/ shared code and interfaces, docs/ notes, tests/ host tests and oracle checks, tools/ on-device probes and generators, sensor-src/ sensor sources used by the T10/T20 builds.

Reporting problems

Open an issue at opensensor/open-tx-isp (kernel driver, ISP, memory) or opensensor/openimp when unsure. Please include the SoC and sensor, the revisions of open-tx-isp, OpenIMP and the streamer, dmesg (including any shortfall line such as set ispmem >= N KB), the streamer log, the stream set and the rmem/ispmem values. Do not post addresses, credentials or location names. Details: Troubleshooting.

Contributing

Contributions are welcome when grounded in OEM binary analysis, libimp ABI validation, hardware logs or captures, tuning/calibration recovery or documentation. For behavioural changes state the OEM evidence, the files changed, how it was validated and what remains uncertain.

Acknowledgments

Prior art from the Ingenic / Thingino reverse-engineering community, especially thingino-firmware, ingenic-sdk and OpenIMP, and the upstream opensensor/open-tx-isp.

License

This project is licensed under the GNU General Public License (GPLv3).

---

_{Not affiliated with or endorsed by Ingenic Semiconductor. "Ingenic" is used only to name the SoCs this project supports.}