ISP source compilation: umbrella tracker for all platforms

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Overview

Tracking ISP subsystem openness across all HiSilicon platforms. The ISP pipeline spans kernel modules (open_isp.ko, open_sensor_i2c.ko, open_mipi_rx.ko) and userspace libraries (libisp.so, libsns_*.so). The goal is to compile as much as possible from source instead of shipping vendor binary blobs.

The key architectural split is between V1–V3A (ISP algorithms in the kernel module) and V4 (algorithms in userspace libisp.so). Source code exists for most platforms but is not always wired into the build.

Platform Comparison

Platform	Gen	ISP kernel .ko	ISP userspace libisp.so	Sensors libsns_*.so	MIPI RX	VI	sensor_i2c
hi3516ev200	V4	Source (HAL+shared mkp)	Source (41 .c)	30 sensors, source	Source	Blob	Source
gk7205v200	V4	symlink→ev200	symlink→ev200	symlink→ev200	shared	Blob	shared
hi3516cv500	V3.5	Source (7 .c)	Source (41 .c)	20 sensors, source	Source	Blob	Source
hi3516cv200	V2	Source (6 .c)	Not built (34 .c exist)	10 sensors, source	Source	Blob	Source
hi3516av100	V2A	Blob (33 .c exist)	Not built (25 .c exist)	14 sensors, source	Source	Blob	Source
hi3516cv300	V3	Blob (43 .c exist)	Not built (38 .c exist)	9 sensors, source	Source	Blob	Source
hi3519v101	V3A	Blob (40 .c exist)	Not built (35 .c exist)	9 sensors, source	Source	Blob	Source
hi3516cv100	V1	Blob (no source)	None (no source)	16 sensors, source	None	Blob	Blob

Where 3A Algorithms Live

The ISP algorithms (AE, AWB, AF, demosaic, sharpening, DRC, noise reduction, etc.) are the core image quality code. They live in different places depending on chip generation:

Generation	Platforms	Algorithms location	Count
V4	ev200, gk7205v200	Userspace libraries/isp/arch/hi3516ev200/algorithms/	37 .c files
V3.5	cv500	Userspace libraries/isp/arch/hi3516cv500/algorithms/	37 .c files
V1–V3A	cv100, cv200, av100, cv300, v101	Kernel kernel/isp/arch/<platform>/firmware/src/algorithms/	16–30 .c files

For V1–V3A, the algorithms are compiled into open_isp.ko itself. For V4/V3.5, the kernel module is a thin HAL and the algorithms run in userspace via libisp.so.

Source Available But Not Built

Three platforms have full ISP firmware source checked into the repo but still build from .o blobs:

Platform	Blob in build	Source available	Kernel .c files	Userspace .c files
hi3516av100	obj/hi3516av100/hi3516a_isp.o	isp/arch/hi3516av100/firmware/	33	25
hi3516cv300	obj/hi3516cv300/hi_isp.o	isp/arch/hi3516cv300/firmware/	43	38
hi3519v101	obj/hi3519v101/hi3519v101_isp.o	isp/arch/hi3519v101/firmware/	40	35

The kbuild files for CV300 and V101 have comments acknowledging this:

• hi3516cv300.kbuild:120: # --- ISP module (blob — full ISP source available but uses blob for now) ---
• hi3519v101.kbuild:134: # --- ISP module (blob) ---

Similarly, libraries/isp/arch/ has userspace ISP algorithm source for these platforms, but libraries/Makefile filters them out — only CV500 and EV200 currently build libisp.so.

hi3516cv200 is the exception: its kernel ISP already builds from source (6 .c files from firmware/drv/ + firmware/vreg/), but it still lacks a userspace libisp.so build.

Current Build Wiring

Kernel ISP (kernel/Kbuild dispatch)

• V4 (ev200/gk7205v200): Falls through to generic else branch → kernel/isp/Kbuild builds from shared isp/mkp/src/ + isp/arch/hi3516ev200/hal/isp_drv.c
• V3.5 (cv500): hi3516cv500.kbuild → source from isp/arch/hi3516cv500/{hal,mkp/src,init}/ (7 .c files, own copies of mkp)
• V2 (cv200): hi3516cv200.kbuild → source from isp/arch/hi3516cv200/firmware/{drv,vreg}/ (6 .c files)
• V2A, V3, V3A (av100, cv300, v101): Platform .kbuild → blob from obj/<platform>/ + init wrapper
• V1 (cv100): Platform .kbuild → blob, no source exists

Userspace ISP (libraries/Makefile dispatch)

• ev200/gk7205v200: No CHIPARCH filter → all subdirs built including ./isp/
• cv500: Explicit filter includes ./isp/
• All others: Filtered to ./sensor/<platform>/ only — no libisp.so built

Sensor Callback Path (runtime AE/AGC updates)

Two I2C write paths exist for all platforms:

1. Init path (userspace direct): IMX335_init() → write(/dev/i2c-N) — programs full register table at startup
2. Runtime path (kernel callback): ISP AE computes new exposure/gain → fills ISP_SNS_REGS_INFO_S → kernel ISP writes on VSync via pfnISPWriteI2CData → sensor_i2c.ko → i2c_master_send() — verified working on hi3516ev300 test camera

Remaining Binary Dependencies

Per-platform blob modules (not ISP-specific)

open_vi.ko (Video Input) is blob on every platform — no source exists anywhere in the repo. This is the single biggest remaining binary dependency across all platforms.

Other blob modules (base, sys, venc, vpss, etc.) are tracked in #51.

Recommended Priority for ISP Source Migration

1. hi3516cv200 — Kernel ISP already source. Wire up libisp.so build (34 .c files exist in libraries/isp/arch/hi3516cv200/). Lowest risk since kernel side is proven.
2. hi3516av100 — Switch kbuild from blob to source (33 .c files). Same firmware/ tree layout as cv200 which already works. Also wire up userspace libisp (25 .c).
3. hi3516cv300 — Switch kbuild from blob to source (43 .c files, most complete). Also wire up userspace libisp (38 .c).
4. hi3519v101 — Switch kbuild from blob to source (40 .c files). Also wire up userspace libisp (35 .c).
5. hi3516cv100 — No ISP source exists. Would need reverse engineering or SDK extraction. Not worth pursuing.

Per-Platform Sub-Issues

Platform	Issue	Status
hi3516ev200 / gk7205v200	No issue needed	Fully source — kernel ISP + libisp + sensors
hi3516cv500	No issue needed	Fully source — kernel ISP + libisp + sensors
hi3516cv200	TBD	Kernel ISP from source; userspace libisp source exists but not wired
hi3516av100	TBD	Both kernel + userspace ISP source exist, neither wired
hi3516cv300	TBD	Both kernel + userspace ISP source exist, neither wired
hi3519v101	TBD	Both kernel + userspace ISP source exist, neither wired
hi3516cv100	N/A	No ISP source available

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Cross-referencing a concrete blocker found while implementing #144 (sensor frame-start IRQ chrdev) against this matrix:

Three SoCs that have ISP source in-tree but build the vendor blob today prevent kernel-side ISP hooks from taking effect:

SoC	Kbuild target	Source location	Status
hi3516av100	kernel/hi3516av100.kbuild:67 — $(AV100_BLOB_DIR)/hi3516a_isp.o	kernel/isp/arch/hi3516av100/firmware/drv/isp.c (open, with ISP_ISR + ISP_IntUserBottomHalf)	Blob built, source unused
hi3516cv300	kernel/hi3516cv300.kbuild:121 — $(CV300_BLOB_DIR)/hi_isp.o (comment in-file: "full ISP source available but uses blob for now")	kernel/isp/arch/hi3516cv300/firmware/drv/isp.c (open, same pattern)	Blob built, source unused
hi3519v101	kernel/hi3519v101.kbuild:135 — $(V101_BLOB_DIR)/hi3519v101_isp.o	kernel/isp/arch/hi3519v101/firmware/drv/isp.c (open, canonical reference for the ISP_ISR pattern)	Blob built, source unused

For comparison, hi3516cv200 already builds ISP from firmware/drv/isp.o (per hi3516cv200.kbuild:177) — single working data point that source builds today on a V1–V3A SoC. So this is a per-SoC kbuild flip, not a missing-source problem.

Impact on #144: the frame-start hook in ISP_ISR only takes effect on cv200, ev200/ev300, gk7205v200, and cv500 (the last three are MIPI-RX-based and bypass ISP entirely). av100/cv300/v101 source patches are present but no-op until each `.kbuild` is flipped from blob → source. Until that happens, those three SoCs cannot get NTP-anchored frame timestamps.

Same blocker will recur for any future kernel-side ISP feature on these SoCs.