RZA1H QCA9377-3 UART BT integration quesiton

Hi,

I am working on QCA9377-3 UART BT integration on Renesas Starter Kit+ for RZ/A1H.

the BT is connected with USB to UART convert and USB host connector (CN9)

BSP information as below:

Linux-4.9 BSP: github.com/.../rza_linux-4.9_bsp
Linux-4.9 / u-boot-2017.05 / Buildroot-2017.02

Enable BT command

1. hciattach /dev/ttyUSB0 qca 3000000 -t120 flow --> there is Bluetooth: hci0: Frame reassembly failed (-84) after this command.
2. hciconfig hci0 up --> Bluetooth: hci0: Frame reassembly failed (-84) is keeping output after this command

Anyone can share any comment for this error message??

the same QCA9377-3 EVB works well on Ubutun 4.9 OS with Lenovo T420 laptop.

Austin