secubox-deb/kernel-build

SecuBox MOCHAbin Kernel Build

Custom Linux 6.6.x LTS kernel for Marvell Armada 7040 (MOCHAbin) with OpenWrt-style built-in drivers.

Important: Use kernel 6.6.x (same as OpenWrt) for reliable I2C/LED support. Kernel 6.12.x has mv64xxx I2C driver timing issues that cause LED write failures.

Features

Built-in Drivers (=y)

Critical boot drivers are built-in to avoid deferred probe issues:

Category	Driver	Config
DSA	mv88e6xxx switch	CONFIG_NET_DSA_MV88E6XXX=y
Ethernet	Marvell PPv2	CONFIG_MVPP2=y
PHY	Marvell 1G/10G	CONFIG_MARVELL_PHY=y, CONFIG_MARVELL_10G_PHY=y
Storage	Xenon SDHCI (eMMC)	CONFIG_MMC_SDHCI_XENON=y
Storage	AHCI SATA	CONFIG_AHCI_MVEBU=y
USB	XHCI Host	CONFIG_USB_XHCI_HCD=y
ComPHY	CP110 PHY	CONFIG_PHY_MVEBU_CP110_COMPHY=y

Module Drivers (=m)

Drivers as modules for flexibility and recovery:

Module	Purpose
leds-is31fl319x	LED controller (module allows I2C recovery)
usbnet	USB network framework
cdc_ether	CDC-ECM USB Ethernet
cdc_ncm	CDC-NCM USB Ethernet
rndis_host	RNDIS USB Ethernet

Note: LED driver is a module to allow recovery from I2C bus hangs:

rmmod leds_is31fl319x && modprobe leds_is31fl319x

Build Instructions

Prerequisites

# Install cross-compiler
sudo apt install gcc-aarch64-linux-gnu

# Get kernel source
wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.6.137.tar.xz
tar xf linux-6.6.137.tar.xz
cd linux-6.6.137

Apply I2C/LED Patches

Apply patches to fix I2C timing issues with the IS31FL319X LED driver:

# From kernel source directory
cd linux-6.6.137

# Apply LED driver delay patch
patch -p1 < ../kernel-build/patches/001-leds-is31fl319x-add-i2c-delays.patch

# Apply I2C errata delay increase patch
patch -p1 < ../kernel-build/patches/002-i2c-mv64xxx-increase-errata-delay.patch

Configuration

# Start with defconfig
make ARCH=arm64 defconfig

# Merge SecuBox fragment
scripts/kconfig/merge_config.sh -m .config \
    ../board/mochabin/kernel/config-6.12-openwrt-merged.fragment

# Finalize config
make ARCH=arm64 olddefconfig

Build

# Build kernel (cross-compile for ARM64)
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j$(nproc)

# Output: arch/arm64/boot/Image

Deploy

# Copy to MOCHAbin
scp arch/arm64/boot/Image root@C3BOX:/boot/Image-openwrt

# Update boot menu (already configured in extlinux.conf)
ssh root@C3BOX reboot

Config Fragment

The main configuration is in:

board/mochabin/kernel/config-6.12-openwrt-merged.fragment

This fragment merges:

• OpenWrt MVEBU/Cortex-A72 kernel config (built-in drivers)
• Debian systemd compatibility requirements
• SecuBox-specific features (LED, USB network)

Key Sections

1. ARCHITECTURE - ARM64 Cortex-A72, 4K pages, 39-bit VA
2. MVEBU PLATFORM - Armada 8K/7040, GIC-v3, clock/reset
3. BOOT CRITICAL - Storage (MMC, SATA), filesystems (ext4, FAT)
4. NETWORK - PPv2 Ethernet, DSA switch, PHYs
5. USB HOST - XHCI, EHCI, OHCI
6. I2C/LED - MV64XXX I2C, IS31FL319X LED
7. SYSTEMD - cgroups, namespaces, BPF, seccomp
8. CRYPTO - ChaCha20, AES, hardware CESA

Boot Configuration

Extlinux boot menu at /boot/extlinux/extlinux.conf:

DEFAULT openwrt
TIMEOUT 50
PROMPT 1
MENU TITLE SecuBox MOCHAbin Boot Menu

LABEL openwrt
    MENU LABEL 1. OpenWrt-style Kernel (DSA built-in)
    KERNEL /Image-openwrt
    FDT /armada-7040-mochabin-openwrt.dtb
    APPEND root=/dev/mmcblk0p2 rootfstype=ext4 rw rootwait console=ttyS0,115200

LED Hardware

MOCHAbin has 9 RGB LEDs controlled by an IS31FL3199 chip:

• Bus: I2C-1
• Address: 0x64
• Driver: leds-is31fl319x

After boot, LEDs should appear at:

ls /sys/class/leds/
# is31fl3199:led0 ... is31fl3199:led8

Troubleshooting

DSA switch not working

• Ensure CONFIG_NET_DSA_MV88E6XXX=y (not =m)
• Check dmesg for mv88e6xxx probe messages

LEDs not appearing

• Check I2C bus: i2cdetect -y 1 (should show 0x64)
• Check driver loaded: dmesg | grep is31fl
• Verify DTS has correct node

LED I2C errors (-EIO)

Symptoms:

leds green:led1: Setting an LED's brightness failed (-5)

The mv64xxx I2C driver on Marvell Armada platforms has timing issues (errata FE-8471889). The mainline kernel has a 5µs delay fix, but this is sometimes insufficient for LED controllers.

Solution: Apply the patches in kernel-build/patches/:

1. 001-leds-is31fl319x-add-i2c-delays.patch - Adds 1ms delays between I2C writes in LED driver
2. 002-i2c-mv64xxx-increase-errata-delay.patch - Increases errata delay from 5µs to 50µs

After patching and rebuilding the kernel, LED timer triggers should work without errors.

Alternative workaround (without kernel rebuild): Use slow kernel timers (2-4 second cycles) via secubox-led-trigger script instead of rapid userspace updates. The slow timers give the I2C bus time to settle between writes.

USB network not working

• Load modules: modprobe cdc_ether
• Check dmesg when plugging Eye Remote

Related Issues

• GitHub Issue #60: Kernel build tracking
• GitHub Issue #45: IS31FL3199 driver
• GitHub Issue #39: LED heartbeat port

Author

Gerald KERMA devel@cybermind.fr CyberMind — https://cybermind.fr