HCI_UART on NRF52840, attaching the device on a Yocto based Linux SBC errors out saying “Can't init device hci0: Cannot assign requested address (99)”

[Maneesh N]

Hello all,

I'm fairly new to BLE and Linux BlueZ.

I'm trying to interface a Mikrobus BLE module based on nrf52840dk to our Yocto based Linux SBC (Rugged board i.MX6-UL), I have flashed Zephyr's hci_uart code onto the module.
The module seems to work fine when attached on a Linux PC (Ubuntu) using hciattach command but on our SBC / BLE gateway the device fails to get inited and errors out like this

root@rb-imx6:~# hciconfig hci0 up

root@rb-imx6:~# Can't init device hci0: Cannot assign requested address (99)

it'd be great if anyone could help me figure out this issue.

Thanks in advance.

[Maneesh N]

So I ran btmon while attaching the device and saw that it was erroring out here,

bluetoothd: ../bluez-5.55/src/adapter.c:get_static_addr() Failed to open crypto

On googling this issue I got to know that, when attaching the UART HCI controller with btattach, BlueZ was not able to create a static address, because of missing Linux kernel crypto interface in user-space. Compiling the kernel with these configs helped me solve the issue.

CONFIG_CRYPTO_USER
CONFIG_CRYPTO_USER_API
CONFIG_CRYPTO_USER_API_AEAD
CONFIG_CRYPTO_USER_API_HASH

CONFIG_CRYPTO_AES
CONFIG_CRYPTO_CCM
CONFIG_CRYPTO_AEAD
CONFIG_CRYPTO_CMAC