How to configure USART2/BT with no hardware flow control

We are using MuRata Module LBEE5HY1MW on our custom board based on OSD32MP157. Wi-Fi is working ok, but BT fails to initialize.

Here are the hardware pin connections between 1MW BT module and SiP:

1MW BT module  OSD32MP157F SiP

BT_UART_RTS => USART2_RTS (PA1)

BT_UART_CTS => USART2_CTS (PE15)

BT_UART_RXD => USART2_TX (PA2)

BT_UART_TXD => USART2_RX (PA3)

We noticed that RTS/CTS pin connection is wrong and we can not change it on the current board version.

We want to configure the USART2/BT with “no hardware flow control” which require RTS/CTS signals has to be pulled active low.

I’ve made following changes in kernel device-tree, removed RTS/CTS from pinctrl block and applied pull-down in bluetooth block.

&pinctrl {

usart2_pins_mx: usart2_mx-0 {

pins1 {

pinmux = <STM32_PINMUX(‘A’, 3, AF7)>; /* USART2_RX */

bias-disable;

};

pins2 {

pinmux = <STM32_PINMUX(‘A’, 2, AF7)>; /* USART2_TX */

bias-disable;

drive-push-pull;

slew-rate = <0>;

};

};

usart2_sleep_pins_mx: usart2_sleep_mx-0 {

pins {

pinmux = <STM32_PINMUX(‘A’, 2, ANALOG)>, /* USART2_TX */

<STM32_PINMUX(‘A’, 3, ANALOG)>; /* USART2_RX */

};

};

};

/* Bluetooth */

&usart2{

pinctrl-names = “default”, “sleep”;

pinctrl-0 = <&usart2_pins_mx>;

pinctrl-1 = <&usart2_sleep_pins_mx>;

status = “okay”;

bluetooth {

shutdown-gpios = <&gpioe 10 GPIO_ACTIVE_HIGH>;

gpios = <&gpioe 15 GPIO_PULL_DOWN>, /* PE15 USART2_CTS apply pull-down*/

<&gpioa 1 GPIO_PULL_DOWN>; /* PA1 USART2_RTS apply pull-down */

compatible = “brcm,bcm4345c5”;

max-speed = <3000000>;

vbat-supply = <&v3v3_eth>;

vddio-supply = <&v3v3>;

};

};

Using following firmware from murata github.

BCM4345C0_003.001.025.0172.0344.1MW.hcd

cyfmac43455-sdio.1MW.txt

cyfmac43455-sdio.bin

cyfmac43455-sdio.1MW.clm_blob

Getting following timeout error during BT initialization.

debian@device123:~$ dmesg | grep -i blue

[   16.922303] Bluetooth: Core ver 2.22

[   16.928872] Bluetooth: HCI device and connection manager initialized

[   17.020394] Bluetooth: HCI socket layer initialized

[   17.023853] Bluetooth: L2CAP socket layer initialized

[   17.028934] Bluetooth: SCO socket layer initialized

[   18.018175] Bluetooth: HCI UART driver ver 2.3

[   18.021322] Bluetooth: HCI UART protocol H4 registered

[   18.045556] Bluetooth: HCI UART protocol Broadcom registered

[   20.410427] Bluetooth: hci0: command 0xfc18 tx timeout

[   28.650237] Bluetooth: hci0: BCM: failed to write update baudrate (-110)

[   28.655497] Bluetooth: hci0: Failed to set baudrate

[   30.730307] Bluetooth: hci0: command 0x0c03 tx timeout

[   38.890247] Bluetooth: hci0: BCM: Reset failed (-110)

Would appreciate any help resolving this issue.

/Farid