Re: [PATCH 3/4] serial: 8250: Make em485_rts_after_send() set mctrl according to rts state.

[Andy Shevchenko]

On Wed, 2018-06-06 at 11:49 +0200, Giulio Benetti wrote:
> When rs485 enabled and RTS_AFTER_SEND set on startup, need to preserve
> mctrl status, because later functions will call set_mctrl passing
> port->mctrl=0 overriding rts status, resulting in rts pin in
> transmission when idle.
> 
> Make mctrl reflect rts pin state.
> 

This might make sense, I leave it to Matwey to Ack / NAK / etc.
But it also feels that patch 2/4 should be part of this change.

> Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
> ---
>  drivers/tty/serial/8250/8250_port.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c
> b/drivers/tty/serial/8250/8250_port.c
> index 95833cbc4338..c8c10b5ec6d6 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -562,10 +562,13 @@ static inline void
> serial8250_em485_rts_after_send(struct uart_8250_port *p)
>  {
>  	unsigned char mcr = serial8250_in_MCR(p);
>  
> -	if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
> +	if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) {
>  		mcr |= UART_MCR_RTS;
> -	else
> +		p->port.mctrl |= TIOCM_RTS;
> +	} else {
>  		mcr &= ~UART_MCR_RTS;
> +		p->port.mctrl &= ~TIOCM_RTS;
> +	}
>  	serial8250_out_MCR(p, mcr);
>  }
>  

-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy