Hello everyone, I'm using Linux on big endian CPU (one of MIPS-based home routers). Also, I'm trying to use Cypress CYW20704A2 USB-Bluetooth dongle on it. However, `hciconfig hci0 up` failed, and `btmon` showed very specific problem: < HCI Command: LE Write Suggested Default Data Length (0x08|0x0024) plen 4 TX octets: 64256 TX time: 18440 > HCI Event: Command Complete (0x0e) plen 4 LE Write Suggested Default Data Length (0x08|0x0024) ncmd 1 Status: Invalid HCI Command Parameters (0x12) After comparing with similar log on the Linux desktop (where TX octets value is `251`), I came to conclusion that it's an endianness problem, therefore here is a patch that fixes it. Thanks, Andrey --- linux-4.14.104-old/net/bluetooth/hci_core.c 2019-07-07 23:39:44.069862824 +0000 +++ linux-4.14.104/net/bluetooth/hci_core.c 2019-07-07 22:43:21.291838543 +0000 @@ -802,8 +802,8 @@ if (hdev->le_features[0] & HCI_LE_DATA_LEN_EXT) { struct hci_cp_le_write_def_data_len cp; - cp.tx_len = hdev->le_max_tx_len; - cp.tx_time = hdev->le_max_tx_time; + cp.tx_len = cpu_to_le16(hdev->le_max_tx_len); + cp.tx_time = cpu_to_le16(hdev->le_max_tx_time); hci_req_add(req, HCI_OP_LE_WRITE_DEF_DATA_LEN, sizeof(cp), &cp); }