Marcel Holtmann wrote:

Hi Sjur,

quoted

Add CAIF Serial driver. This driver is implemented as a line
discipline. The TTY is opened from inside the kernel module.

caif_serial uses the following module parameters:
ser_ttyname - specifies the tty name.
ser_use_stx - specifies if STart of frame eXtension is in use.
ser_loop    - sets the interface in loopback mode.

I think opening the TTY from within the kernel is the wrong approach.
It basically takes all the control away from the system people trying
to bring up the device. And for every special TTY you need to add
hacks and workarounds.   

You should be just providing the TTY line discipline for CAIF. And
then have a program like caifattach that open the TTY and sets it. We
do this for Bluetooth with hciattach for IrDA with irattach etc.  

I see your point, actually we did this in a while back, 
but changed it to open the tty from kernel side.
I think this is a trade off between flexibility and making it simple to 
use from user space. Another problem with the current approach miss the
flexibility of configuring the UART and the possibility to have multiple 
serial links...

BR/Sjur