Jetson TX2 UART fast baud rate issues

Uart Settings are 921600N8,S2,N.send 14bytes data to pc
TX2 receive and send data is correct.
in 921600N8,S1,N. TX2 send data to pc is correct.but TX2 receive data from pc is not correct.
in lower baud rate is ok.

Above 115200 you need two stop bits. There is an errata about the clock being slightly off, with the two stop bits compensating.

change cbootargs console ttyS0 baudrate to 921600N8S1, console is ok.
other port loopback also is ok.
our board need RS422 connect to other device, so the connection is:
TX2 uartb =1.8v=> FPGA =3.3v=> SN74ALVC164245 =5v=> SN65HVD52DR ==> RS422
we using RS422toUSB cable connect RS422 port to PC to test.
TX2 receive data from pc is not correct.
pc data is fixed.
tx2 receive data is random.

Are you saying the other side of the connection is unable to be configured for two stop bits? If so, then you will probably need a serial USB UART to replace the built-in UART at higher speeds. “8N1” won’t work at those speeds…it needs “8N2”.