ESP32-C6: Using an L2CAP MTU < 255 with BLE causes a runtime error

[lure23]

Bug description

In the trouble examples, MTU values of 128 and 251 are being used. When such examples are being run on ESP32-C6 hardware, the following error occurs:

INFO - [host] setting txq to 24, fragmenting at 255
INFO - [host] configuring host buffers (8 packets of size 251)


====================== PANIC ======================
panicked at /home/ubuntu/trouble.fork/examples/apps/src/ble_bas_peripheral.rs:104:13:
[ble_task] error: BleHost(Hci(Invalid HCI Command Parameters))

@bjoernQ asked me to report this here.

According to him, also ESP32-C2 and ESP32-H2 might be affected (I have only ESP32-C6 to test with).

To Reproduce

1. clone trouble
2. cd examples/esp32
3. edit Cargo.toml in that folder; disable the workaround:

[features]
...
esp32c2 = ["esp-hal/esp32c2", "esp-backtrace/esp32c2", "esp-hal-embassy/esp32c2", "esp-println/esp32c2", "esp-wifi/esp32c2"]
esp32c3 = ["esp-hal/esp32c3", "esp-backtrace/esp32c3", "esp-hal-embassy/esp32c3", "esp-println/esp32c3", "esp-wifi/esp32c3"]
esp32c6 = ["esp-hal/esp32c6", "esp-backtrace/esp32c6", "esp-hal-embassy/esp32c6", "esp-println/esp32c6", "esp-wifi/esp32c6"]
esp32h2 = ["esp-hal/esp32h2", "esp-backtrace/esp32h2", "esp-hal-embassy/esp32h2", "esp-println/esp32h2", "esp-wifi/esp32h2"]

 4. run with:

$ cargo esp32c6 --bin ble_bas_peripheral

Expected behavior

Starts advertising:

...
INFO - [adv] advertising

Actual behaviour

There's a panic at initialization of the BLE stack.

Environment

• Target device: ESP32-C6, -C2, -H2

  Chip type:         esp32c6 (revision v0.0)
  Crystal frequency: 40 MHz
  Flash size:        4MB
  Features:          WiFi 6, BT 5
  

• Crate name and version: esp-hal rev. 7288d0367e0a820db4ca25a22496a35beff1bb61

[bjoernQ]

Thanks!

We need to make parts of BLE_CONFIG (e.g.

esp-hal/esp-wifi/src/ble/os_adapter_esp32c3.rs

Line 249 in 660e43e

pub(crate) fn create_ble_config() -> esp_bt_controller_config_t {

and

esp-hal/esp-wifi/src/ble/os_adapter_esp32c6.rs

Line 16 in 660e43e

pub(crate) static BLE_CONFIG: esp_bt_controller_config_t = esp_bt_controller_config_t {

) user configurable

Unfortunately, it's different for different chips

[lure23]

New data:

• ESP32-C3 works only with MTU >= 251 (not 128..250)

[lure23]

According to this on Matrix, also ESP32-S3 is affected.