Kernel driver for AR0822

Raspberry Pi kernel driver for Onsemi AR0822 — an 8 MP rolling shutter 1/1.8" back side illuminated CMOS sensor.

• 2-lane and 4-lane MIPI CSI-2 (up to 960 Mbps/lane)
• 10-bit and 12-bit RAW output
• 3840×2160 @ 40 fps (full resolution)
• 1920×1080 @ 120 fps (2×2 binning)

Note

This driver supports an experimental eHDR mode, modeled after the IMX708 implementation, by exposing the standard V4L2_CID_WIDE_DYNAMIC_RANGE control. Read more in eHDR (experimental).

Setup

Note

Requires Linux kernel 6.1 or newer. Verify with uname -r.

Install required tools:

sudo apt install -y git
sudo apt install -y --no-install-recommends dkms

Clone this repository:

cd ~
git clone https://github.com/Kurokesu/ar0822-v4l2-driver.git
cd ar0822-v4l2-driver/

Run setup script:

sudo ./setup.sh

Edit boot configuration:

sudo nano /boot/firmware/config.txt

Make two changes:

1. Find camera_auto_detect near the top and set it to 0:

camera_auto_detect=0

2. Add dtoverlay=ar0822 under the [all] section at the bottom of the file:

[all]
dtoverlay=ar0822

Save and exit. Reboot for changes to take effect.

Important

Stock libcamera does not support AR0822 — you must build a patched version for camera to function. See Build libcamera below.

dtoverlay options

ar0822 overlay supports comma-separated options to override defaults:

option	description	default
cam0	Use cam0 port instead of cam1	cam1
4lane	Use 4-lane MIPI CSI-2 (if wired)	2 lanes

cam0

If camera is connected to cam0 port, append ,cam0:

dtoverlay=ar0822,cam0

4lane

To enable 4-lane MIPI CSI-2, append ,4lane:

dtoverlay=ar0822,4lane

Warning

Before using 4lane, confirm your camera port actually supports 4-lane MIPI CSI. Not all Raspberry Pi models and carrier boards provide 4-lane MIPI CSI on both ports.

Tip

Options can be combined. Example — cam0, 4-lane:

dtoverlay=ar0822,cam0,4lane

Build libcamera

Main libcamera repository does not support AR0822. A fork with necessary modifications is available.

On Raspberry Pi, libcamera and rpicam-apps must be rebuilt together. Detailed instructions are available here, but for convenience, here is a shorter version.

Remove pre-installed rpicam-apps:

sudo apt remove --purge rpicam-apps

libcamera

Install dependencies:

sudo apt install -y libboost-dev
sudo apt install -y libgnutls28-dev openssl libtiff5-dev pybind11-dev
sudo apt install -y qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5
sudo apt install -y meson cmake
sudo apt install -y python3-yaml python3-ply
sudo apt install -y libglib2.0-dev libgstreamer-plugins-base1.0-dev

Clone Kurokesu's libcamera fork with AR0822 support:

cd ~
git clone https://github.com/Kurokesu/libcamera.git --branch ar0822
cd libcamera/

Configure with meson:

meson setup build --buildtype=release -Dpipelines=rpi/vc4,rpi/pisp -Dipas=rpi/vc4,rpi/pisp -Dv4l2=enabled -Dgstreamer=enabled -Dtest=false -Dlc-compliance=disabled -Dcam=disabled -Dqcam=disabled -Ddocumentation=disabled -Dpycamera=enabled

Build:

ninja -C build

Install:

sudo ninja -C build install

Tip

On devices with 1 GB of memory or less, build may exceed available memory. Append -j 1 to limit to a single process.

Warning

libcamera does not yet have a stable binary interface. Always build rpicam-apps after building libcamera.

rpicam-apps

Install dependencies:

sudo apt install -y cmake libboost-program-options-dev libdrm-dev libexif-dev
sudo apt install -y libavcodec-dev libavdevice-dev libavformat-dev libswresample-dev
sudo apt install -y libepoxy-dev libpng-dev

Clone Kurokesu's rpicam-apps fork with HDR modifications:

cd ~
git clone https://github.com/Kurokesu/rpicam-apps.git --branch hdr-ar0822
cd rpicam-apps

Configure with meson (libav enabled by default):

meson setup build -Denable_libav=enabled -Denable_drm=enabled -Denable_egl=enabled -Denable_qt=enabled -Denable_opencv=disabled -Denable_tflite=disabled -Denable_hailo=disabled

Important

On Raspberry Pi OS Bookworm, packaged libav* is too old for rpicam-apps newer than v1.9.0.

Bookworm libav workaround

Bookworm ships libavcodec 59.x while newer rpicam-apps expects libavcodec >= 60, causing build errors like "libavcodec API version is too old" (see Raspberry Pi forum thread).

• Keep libav, without eHDR — check out rpicam-apps v1.9.0 before running meson setup (v1.9.0 predates eHDR patches, so eHDR will not be available):

  git checkout v1.9.0

• Keep eHDR, disable libav — stay on hdr-ar0822 branch and disable libav:

  meson setup build -Denable_libav=disabled -Denable_drm=enabled -Denable_egl=enabled -Denable_qt=enabled -Denable_opencv=disabled -Denable_tflite=disabled -Denable_hailo=disabled

Build:

meson compile -C build

Install:

sudo meson install -C build

Tip

This should automatically update ldconfig cache. If you have trouble accessing your new build, update manually:

sudo ldconfig

Verify rpicam-apps build

Verify rpicam-apps was rebuilt correctly:

rpicam-hello --version

Expected output (build date will differ):

rpicam-apps build: v1.11.1 d2836f37957f 25-02-2026 (14:43:27)
rpicam-apps capabilites: egl:1 qt:1 drm:1 libav:1
libcamera build: v0.0.0+6160-8903357b

Verify that ar0822 is detected

Do not forget to reboot!

sudo reboot

List available cameras:

rpicam-hello --list-cameras

Expected output (varies by link frequency and lane configuration):

Available cameras
-----------------
0 : ar0822 [3840x2160 12-bit GRBG] (/base/axi/pcie@1000120000/rp1/i2c@88000/ar0822@10)
    Modes: 'SGRBG10_CSI2P' : 1920x1080 [120.15 fps - (0, 0)/3840x2160 crop]
                             3840x2160 [40.03 fps - (0, 0)/3840x2160 crop]
           'SGRBG12_CSI2P' : 1920x1080 [120.21 fps - (0, 0)/3840x2160 crop]
                             3840x2160 [33.89 fps - (0, 0)/3840x2160 crop]

eHDR (experimental)

AR0822 features an on‑sensor HDR mode that expands dynamic range up to 120 dB by combining three exposures within sensor using the MEC algorithm. To reduce bandwidth requirements, linearized 20‑bit HDR signal is companded to a 12‑bit output.

Important

libcamera pipeline is designed for linear image data from sensor. While Kurokesu's fork HDR implementation is experimental, companded data may show color shifts due to compression.

Due to exposure range limitations, running at maximum fps with current PIXCLK configuration reduces maximum exposure drastically.

For instance, running 4K @ 30 fps results in maximum exposure T1 ≈ 10.26 ms, while running 4K @ 28.8 fps results in T1 ≈ 30.4 ms (right at internal delay buffer limit).

Consider reducing framerate slightly when larger exposure range is desired. This will be addressed in future driver revisions.

eHDR mode is enabled by appending --hdr to rpicam commands.

List eHDR modes

rpicam-hello --list-cameras --hdr

Available cameras
-----------------
0 : ar0822 [3840x2160 12-bit GRBG] (/base/axi/pcie@1000120000/rp1/i2c@88000/ar0822@10)
    Modes: 'SGRBG12_CSI2P' : 1920x1080 [48.04 fps - (0, 0)/3840x2160 crop]
                             3840x2160 [30.01 fps - (0, 0)/3840x2160 crop]

Special thanks

• Will Whang for imx585-v4l2-driver, used as basis for structuring this driver.
• Sasha Shturma's Raspberry Pi CM4 carrier with Hi-Res MIPI Display project. Install script adapted from cm4-panel-jdi-lt070me05000.