Re: [PATCH 6/8] serial: 8250: Copy mctrl when register port.

[Giulio Benetti]

Hi Aaron,

Il 06/06/2018 16:31, Aaron Sierra ha scritto:
> ----- Original Message -----
> > From: "Giulio Benetti" <giulio.benetti@xxxxxxxxxxxxxxxx>
> > Sent: Friday, June 1, 2018 7:40:19 AM
>
> > RS485 can modify mctrl on startup, especially when RTS_AFTER_SEND is on
> > TIOCM_RTS is set, then need to keep it set when registering port.
> >
> > Copy mctrl to new port too.
> >
> > Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
> > ---
> > drivers/tty/serial/8250/8250_core.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/tty/serial/8250/8250_core.c
> > b/drivers/tty/serial/8250/8250_core.c
> > index c8c2b260c681..c8e62fbd6570 100644
> > --- a/drivers/tty/serial/8250/8250_core.c
> > +++ b/drivers/tty/serial/8250/8250_core.c
> > @@ -993,6 +993,7 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
> > 		uart->port.unthrottle	= up->port.unthrottle;
> > 		uart->port.rs485_config	= up->port.rs485_config;
> > 		uart->port.rs485	= up->port.rs485;
> > +		uart->port.mctrl	= up->port.mctrl;
>
> Hi Guilio,
>
> I ran into this same thing about six months ago, but I was able to
> accomplish what I needed by assigning a set_mctrl() function in my
> port definition. Perhaps that would be enough for your case, too?

Thanks for pointing me.
But wouldn't it be better copying mctrl?
In any case, serial8250_register_8250_port() will call:
- uart_add_one_port()
- uart_configure_port()
- port->ops->set_mctrl(port, mctrl);

So it would be a double call IMHO.
Are there any drawbacks on doing what I'm saying?
Maybe I'm missing something.

> You should see a little lower in this file that set_mctrl is copied
> to the new port. > -Aaron
>
> > 		uart->dma		= up->dma;
> > 		uart->em485		= up->em485;
> >
> > --
> > 2.17.0

--
Giulio Benetti
CTO

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