Issue with HW CTRL flow on ttyTHS1

[KevinFFF]

@eduardo45

Something I notice on this one however is that the ttyTHSx present on the 40 pin header is ttyTHS0 (On my previous devkit with JP6.1 it was ttyTHS1). On the brand new dev kit with JP 5.1.2-B104 it is ttyTHS0. Is this expected?

Yes, it should be expected since JP5.x and JP6.x have some differences in device tree for the numbering of UART interface .

@eduardo45

Is this behavior the expected one?

Yes, they are expected that RTS would pull low when it is busy and turn back to high when it is idle.

@eduardo45

1.) Is there any way we can modify the behavior to be the other way? My idea would be to modify serial-tegra.c to directly change the RTS pin by modifying register UART_MCR_0::RTS to toggle RTS on and off (with HW mode disabled). What do you think?

Are you using Uart interface for RS-485 so that you want the opposite behavior?
If so, you can refer to Need to Invert UART2 RTS - #5 by KevinFFF for this use case.