Re: [PATCH v8 3/3] tty: 8250_omap: Use software emulated RS485 direction control

[ÐÐÑÑÑ ÐÐÑÐÐÐÐ]

2016-02-18 10:18 GMT+03:00 ÐÐÑÑÑ ÐÐÑÐÐÐÐ <torso.nafi@xxxxxxxxx>:
> Also, forgot to mention that if serial8250_em485_init is called not
> upon uart startup but elsewhere (upon port register for example), and
> em485 is set, serial8250_do_startup should call
> serial8250_em485_rts_after_send, or else RTS might be in wrong state
> whenever the port device is opened, making it impossible to receive
> data through RTS-controlled RS232<->RS485 hardware converters.

Just found out that it doesn't help. Actually, it is the behavior of
tty_open function to call tty_port_block_til_ready after startup, and
of the latter - to set RTS via ioctl if baud is not zero - both of
which cannot be overriden within the scope of the 8250 framework. The
reason this works in legacy omap_serial is that my GPIO which is used
to emulate RTS is not tied to mctrl there, so the call of
tty_port_block_til_ready does not affect its state.

Therefore, a check for SER_RS485_ENABLED needs to be introduced to
tty_port_block_til_ready.


Regards,
Ilyas G.