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C778 on RV1126B

This guide starts from the LT6911UXE integration profile for Luckfox Aura / RV1126B. Other RV1126B boards need their own CSI, I²C, power, GPIO and audio verification; host pin numbers are not universal.

Integration reference, not completed C778 board acceptance

An LT6911UXE BSP profile exists, but module-side GPIO, clock and wiring assumptions still require verification. Do not assume the Pi dual-half firmware works with this single-CSI profile. No unverified system-flashing recipe is provided here.

Differences from the Pi 5 profile​

ItemExisting Pi 5 factory-test profileCurrent RV1126B reference
CSI pathsTwo parallel half-frame pathsOne four-lane CSI0 path
Pixel dataBGR888_1X24; RGB3 video queueDriver identifies RGB/YUV from the bridge; verify negotiated format
SoftwareLT bridge driver + RP1-CFE + DTBORockchip BSP media drivers + board DTS
Mode evidence960×1080 @ 120 × 2 test contractComplete the mode table using matching single-path firmware and hardware tests

With a left/right split firmware profile, connecting only one CSI path may deliver half an image. Establish how firmware transports a full image before adapting the host.

Board-level configuration​

The Aura reference uses the following assumptions, not a universal wiring table:

  • I²C4, Linux 7-bit address 0x2b. Do not use the vendor's 8-bit address 0x56 directly in a Linux DTS.
  • compatible = "lontium,lt6911uxe"; four data lanes <1 2 3 4>.
  • A 24 MHz xvclk device-tree description; verify how it corresponds to C778's actual clock hardware.
  • Paired CSI endpoints and disabled competing bridge nodes on the same receiver path.
  • Reset, power and plugin-detect GPIOs remain unbound in the example. This does not prove the module never needs these signals.
  • Separate I²S audio via SAI2 M1, subject to module and host pin verification.

Integration sequence​

  1. Lock the board and BSP/kernel revisions and retain a recoverable system image.
  2. Collect the BSP's drivers/media/i2c/lt6911uxe.c, Kconfig/Makefile and receiver-side patches.
  3. Match DTS I²C, CSI endpoints, lanes, clocks and GPIOs to C778's hardware definitions.
  4. Match firmware output, media-bus code and capture format. RGB/YUV mismatches can cause wrong colors, stride errors or no image.
  5. Build and review the DTB and kernel/modules through the BSP's normal process. Deploy using a verified recovery/flashing procedure.
  6. Start with a confirmed low-load input mode, then test the target resolution, rate and audio.

The build host contains Rockchip's LT6911UXE V4L2 media driver, marked GPL-2.0. It is different from the vendor firmware-update example. A timing listed in driver source does not prove that C778 hardware has passed that mode.

The firmware-update example alone is not a complete Linux media stack. The future driver repository will separate capture drivers, board integration and chip firmware maintenance to avoid automatic installation of mismatched firmware.

Inspect a configured system​

These commands collect information without flashing firmware:

uname -a
cat /proc/device-tree/model
v4l2-ctl --list-devices
for media in /dev/media*; do
  [ -e "$media" ] || continue
  media-ctl -d "$media" -p
done
dmesg | grep -Ei 'lt6911|csi|rkcif|dphy|i2c'

After identifying the actual capture node, replace the placeholder below:

# /dev/videoX is a placeholder, not a literal device to copy.
v4l2-ctl -d /dev/videoX --all
v4l2-ctl -d /dev/videoX --list-formats-ext

Once the media path and current format are configured, a short delivery check is:

# Uses the existing configuration; does not configure pads or source timing.
v4l2-ctl -d /dev/videoX --stream-mmap=4 --stream-count=120 --stream-to=/dev/null

If tools are missing, include v4l-utils when building the BSP rootfs. Do not assume a Buildroot image provides apt. MC-centric devices may require media-graph configuration before streaming; see the Linux media-device reference.

Audio and final acceptance​

Verify SDOUT, WS, SCLK, optional MCLK, host input pins and electrical levels separately. A sound-card node does not prove valid audio. Record and check sample rate, channels, clocks and continuity.

Published compatibility should identify host board, system, kernel, driver, DTS, chip firmware, input timing, capture format/rate and audio results. RV1126B remains an integration reference until hardware acceptance is complete.

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