Hi @alaskora_byk_mstang,
I hope you are doing well.
UART baudrate depende upon module clock of UART.
module_clock frequency must always be greater or equal to 16x the maximum baud rate.
default module_clock frequency is 24 MHz.
Please make below change in uart node to support 4Mbps baudrate.
&uart1 { /* BT */
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart1>;
assigned-clocks = <&clk IMX8MM_CLK_UART1>;
assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
fsl,uart-has-rtscts;
status = "okay";
};
Thanks & Regards,
Dhruvit Vasavada