serial: imx: rs485: State of rts pin during tty device is closed

[Christoph Niedermaier]

Hello,

I have some problems with the uart rs485 mode on my imx6ull. I
discovered that the rts pin is high when the tty device is closed. In
my case it means the rs485 transceiver is active and all signal from
Tx going through onto the rs485 bus. The reason for my problem is that
I also have a microcontroller on this rs485 transceiver. So I expected
when I don't use the uart in Linux (device closed) the rts signal isn't
active. If I have the device in Linux opened everything is OK, because
only on sending the rts pin will be active. So for me it makes no sense
to have the rts pin active (in rs485 mode) when the device is closed.

Could someone maybe answer my following question:
Is this a hardware restriction of the imx6ull soc uart core or
can this be handled by the imx driver or
do I have a lack of understanding here?


Regards
Christoph