`sample.bluetooth.hci_usb.device_next` broken on stm32wb55

[lopsided98]

Describe the bug

The hci_usb sample is non-functional when used with the new USB device stack on the STM32WB55. The command buffer sent to the HCI driver is malformed, with buf->data == NULL and buf->len > buf->size, causing the following error message to be printed: bt_hci: Error sending to driver.

I'm having some trouble following the data flow in the udc_stm32 driver, but I traced at least as far as HAL_PCD_DataOutStageCallback(). In that function, udc_buf_get() returns a buffer with len == size == 0 and data == NULL. The code then proceeds to call net_buf_add(buf, rx_count) on the buffer, where rx_count > 0. This results in the buffer with len > size and would cause a assertion failure with CONFIG_ASSERT. In practice, enabling CONFIG_ASSERT causes a crash earlier due to #61464.

To Reproduce Steps to reproduce the behavior:

1. Connect Nucleo WB55 board
2. Add missing NULL argument to sample_usbd_init_device() call in hci_usb sample to fix build
3. west build samples/bluetooth/hci_usb -DCONF_FILE=usbd_next_prj.conf --board nucleo_wb55rg
4. west flash
5. Observe that the USB HCI device does not work

Expected behavior hci_usb should be functional with the new USB stack

Impact The old USB stack must be used to get hci_usb functionality on the STM32WB55.

Logs and console output

*** Booting Zephyr OS build v3.6.0-1547-g6c300c9c66e7 ***
[00:00:00.003,000] <inf> bt_hci_raw: Bluetooth enabled in RAW mode
[00:00:00.004,000] <err> usbd_core: Failed to set default address after bus reset
Bluetooth over USB sample
[00:00:00.463,000] <inf> bt_hci: Configuration enabled
[00:00:00.464,000] <err> bt_hci: Error sending to driver

Environment:

• OS: Linux
• Toolchain: GCC 13.2.0
• Zephyr: v3.6.0-1547-g6c300c9c66e7

cc @loicpoulain

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CC @erwango @FRASTM @ABOSTM @gautierg-st @Desvauxm-st @GeorgeCGV

[lopsided98]

After playing with hci_usb (with the old USB stack) on the STM32WB55, it looks like the M0+ HCI firmware is far too buggy to be usable with Linux, so this is definitely a low priority.

[github-actions[bot]]

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[erwango]

@asm5878 to provide an update

[asm5878]

ST doesn't support hci over usb way of working with STM32WB product. And a feature update is not planned.

Sorry, but I think we can close this ticket as a solution cannot be provided.