Re: [PATCH/RFC] 8250: Auto RS485 direction control

Grant Edwards
2008-08-04T16:15:27Z

On 2008-08-04, Laurent Pinchart <laurentp@cse-semaphore.com> wrote:
> On Monday 04 August 2008, Tosoni wrote:
>> About the flags names -- CARTS, UART_FCTR_RS485
>>
>> May I suggest CRTSTOGGLE since it is known by that kind of name in other
>> OS's :-)
>
> I like Russell's proposal of sticking to CRTSCTS and adding options to setserial:
>
>> Should CRTSCTS be a global "enable some kind of flow control" bit and
>> setserial be used to configure the actual flow control method
>> (conventional RTS/CTS, DTR/DSR, alternate RTS/CTS, RS485 on RTS,
>> RS485 on DTR) ?
>
> Any opinion on that ?

Opposed.

1) CRTSCTS means something quite specific. Rather than
overload that name for something unrelated, create a new
mode bit for the new mode.

2) Most of what's in setserial is useless and irrelevent to
non-PC-motherboard-16550-uart serial ports (the drivers for
which often don't support setserial).

Let's just suck it up and do it the right way.

>> And further, it says was RTS will do, instead of why. Maybe
>> someone could use it for something other than RS485 ?
>
> I agree with you here. The name should reflect that RTS is
> used in 'envelope' mode (asserted during data transmission,
> idle between frames).

I don't really care what the name is. "RTS toggle" or
"half-duplex" is what everybody I know calls it.

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