zephyr: BLE scanning - BT RX thread hangs on.

Describe the bug During ble scan the BT RX thread hangs on and ble scan callback is not fired. This happens at random time after scan start.

To Reproduce Example: bluetooth/scan_adv west build -b nucleo_wb55rg .

scan parameters:

• BT_HCI_LE_SCAN_ACTIVE
• BT_LE_SCAN_OPT_NONE
• interval=128 (tried with other values too)
• windows=64 (tried with other values too)

Expected behavior Scanning is going continously until manually stopped.

Impact Hard reset has to be done to begin scanning again.

Logs and console output As you can see below the number of cpu ticks of BT RX thread doesn’t change for following threads analysis (time interval = 30s)

Environment (please complete the following information):

• OS: Linux
• Zephyr SDK 3.1.99
• FUS v.1.2.0
• ble stack: stm32wb5x_BLE_Stack_full_fw (1.12.1) on stm32wb55 nucleo
• ble stack: stm32wb5x_BLE_HCILayer_extended_fw (1.13.2) on own hardware
• boards: stm32wb55 nucleo, own pcb based on stm32wb55 mcu

Additional context This issue occurs on our own hardware based on stm32wb55 mcu and on stm32wb55 nucleo board. There are different ble stacks used as mentioned in Environment section.

This issue occurs at random time (from my observations this time depends on scan parameters, when scan interval and window are bigger then it’s harder to reproduce this issue).

When performing tests on scan_adv example i’ve commented the code part responsible for advertising. Only scanning is performed.

Also i tried to do some workaround and try to reset the bt stack when noticed that this issue occured, but there is another problem. When i do: (pseudocode:) bt_le_scan_disable(); hci_command->BT_HCI_OP_RESET bt_disable(); bt_enable();

I’m getting an assertion:

Adding this line in hci_core.c bt_enable() resolves problem with assertion. k_work_queue_init(&bt_workq);