I tried to connect a uart device via 40-pin gpio (uart9_tx and uart9_rx) but
doesn’t work. In rk3568-bpi-r2-pro.dts device tree, changed status to okay in
After rebooting the machine, I cannot see the /dev/ttyS9 device node.
Does anyone know how to fix it? Thanks.
uart9 is not mapped to ttyS9
Look for adress of uart9 in dtsi and search this in dmesg then there should be an entry with ttySx. If not try to increase the max uarts in your kernel
So address is fe6d0000 and should visible in dmesg if device is probed successfully.
After fixing your link to dts i see my comment that uart9 is pin-shared with
pwm13 and pwm12/spi3…have you disabled these nodes?
@frank-w Thank you very much for your help. After increasing the max uarts, I can see that device node.