Device Tree • How to run RS485 for uart0, and uart3?

I am using "Raspberry Pi Compute Module 5 Rev 1.0" with Openwrt firmware having 6.12.55 kernel version.
In this I am not able to get RX bytes on serial interface so accordingly no RX is happening. I added following dts overlay for serial ports. DE and RE are tied to RTS. I don't see RTS toggling on oscilloscope, it is always high.

In config.txt I have written this-
#Enable ttyAMA0
dtoverlay=uart0-pi5,ctsrts=on
dtparam=uart0-pi5=on

#Enable ttyAMA3
dtoverlay=uart3-pi5,ctsrts=on,rs485=on,rs485_invert_rts=on
dtparam=uart3-pi5=on

here is the pinctrl details-
8: a2 pn | hi // GPIO8 = TXD3
9: a2 pu | hi // GPIO9 = RXD3
10: a2 pu | hi // GPIO10 = CTS3
11: a2 pn | lo // GPIO11 = RTS3

What can be issue, please suggest.

Statistics: Posted by shailesh170 — Wed Dec 17, 2025 6:10 am

---