[LEDE-DEV] Serial Port unusable in Ramips RT5350 target after disabling serial console

[Tobias Welz]

Hello All,

I'm currently struggling with using serial port on Ramips RT5350 Target 
- for me it looks like a bug. I tried this on an Intenso M2M drive and 
and WIZnet WizFi630A.

used boards:
- Intenso M2M has one serial port, with the console /dev/ttyS0
- WIZnet WizFi has two serial ports /dev/ttyS0 and /dev/ttyS1 which also 
has the console.

If I use stock Lede (tried OpenWrt as well) I can communicate with the 
console on both devices - so the serial port/setup is fine on my PC.

Then I disabled the EarlyPrintK and added console=null to the kernel 
parameters and removed the "ash" line from /etc/inittab. So far as 
expected I don't get output on the former console port.

when I now run
minicom -D /dev/ttyS0 -b 115200
on the WizFi (which accesses the Port that was not used as console 
before) I can communicate bidirectional. Everything fine as expected.

when I run
minicom -D /dev/ttyS1 -b 115200
on the WizFi (or ttyS0 on the Intenso M2M) datatransmission is only 
unidirectional.
I can send Data from the PC to the serial port and receive it via minicom.
But when I send data from minicom it is not sent to the serial port!

Can someone give me a hint where to look or investigate more closely?

Regards Tobias