/jetson-customize-camera

Camera overlay regeneration recipe (referenced by SKILL.md §6)

The committed tegra<soc>-overlay-<carrier_short>-camera.dts is regenerated from the in-tree NVIDIA reference templates. The templates are read-only inputs; the agent never #includes them into the carrier overlay at compile time, never copies the in-tree __fixups__ placeholder pattern, and never ships the artefact with unresolved macros from dt-bindings/.

Source templates (read-only inputs)

For SoC <soc> ∈ {t264 (Thor), t23x (Orin)}:

$L4T_DIR/source/hardware/nvidia/<soc>/nv-public/overlay/
  tegra<soc>-p3971-camera-<sensor>-overlay.dts          # connectivity + status="okay" overrides
  tegra<soc>-camera-<sensor>*.dtsi                      # sensor body (mode tables, regulators, labels)
  tegra<soc>-p3971-camera-modules.dtsi                  # disabled-by-default tegra-camera-platform skeleton

For Thor with the dual-IMX274 selection:

The dtsi defines all the cross-fragment endpoint labels (liimx274_csi_in0/1, liimx274_csi_out0/1, liimx274_imx274_out0/1, liimx274_vi_in0/1) inline, so a preprocessed-and-merged DTS resolves them via __local_fixups__.

Recipe

1. Stitch input. Inject #include "<sensor>.dtsi" after the gpio binding include in the per-sensor overlay file. This is a build-time stitch, not a runtime dependency:

   awk '/^#include <dt-bindings\/gpio\/tegra<soc>-gpio.h>/{
           print; print "#include \"tegra<soc>-camera-<sensor>*.dtsi\""; next}
        {print}' \
       $SRC/tegra<soc>-p3971-camera-<sensor>-overlay.dts > /tmp/cam_render/input.dts

2. Materialise macros via cpp -E. Resolve every dt-bindings symbol to its literal value before any DTC pass:

   cpp -nostdinc -undef -x assembler-with-cpp \
       -I $SRC \
       -I $L4T_DIR/source/hardware/nvidia/<soc>/nv-public/include/kernel-<soc> \
       -I $L4T_DIR/source/kernel/kernel-noble/include \
       /tmp/cam_render/input.dts -o /tmp/cam_render/expanded.dts

   expanded.dts now contains literal clock IDs (<&bpmp 278U>), literal GPIO offsets (<&gpio_main 0x12 0>), and the full sensor body inlined. No more TEGRA264_CLK_EXTPERIPH1, no more CAM0_RST_L, no more GPIO_ACTIVE_HIGH.

3. Transform for the carrier. Programmatically rewrite the expansion:

   • Strip cpp # N "file" line markers and SPDX headers emitted by the preprocessor; collapse consecutive blank lines.
   • Replace overlay-name = "Jetson Camera ..." with "<carrier_short> <sensor_id>".
   • Replace the in-tree devkit compatible string list with compatible = derived from the base kernel DTB's /compatible (read with dtc -I dtb -O dts $L4T_DIR/kernel/dtb/<DTB_FILE> then sed -n '/^\/ {/,/^};/p' | grep '^[[:space:]]*compatible').
   • Replace board_config.ids = "LPRD-..." with a carrier-specific stub the carrier's daughter-card EEPROM (or a software stub) reports.
   • Substitute per-sensor wiring answers from session.camera: reset-gpios (controller + offset), mux.channel (which i2c@<ch> block under tca9546@70), port-index (CSI port per sensor), bus-width, vc-id.
   • Prepend the mandatory header comment (carrier short, sensor selection, CSI port + lane assignments, MCLK + reset GPIO per sensor, the reference template paths, the citation list).

4. Compile + verify.

   dtc -@ -I dts -O dtb \
       -o $L4T_DIR/kernel/dtb/tegra<soc>-overlay-<carrier_short>-camera.dtbo \
       <carrier_short>-camera.dts
   fdtoverlay -i $L4T_DIR/kernel/dtb/<DTB_FILE> -o /tmp/m.dtb \
       $L4T_DIR/kernel/dtb/tegra<soc>-overlay-<carrier_short>-camera.dtbo
   strings /tmp/m.dtb | grep -E '<sensor>|tca9546|skip_mux_detect'

   fdtoverlay MUST exit zero. The grep MUST return ≥1 hit per expected substring. If FDT_ERR_NOTFOUND, an external &label reference doesn't resolve in the base DTB's __symbols__; fix it before flashing.

Invariants in the regenerated DTS

Per-carrier substitution table