[PATCH v2] mxs: uart: allow setting RTS from software

[PATCH v2] mxs: uart: allow setting RTS from software

[Steffen Trumtrar]

With the patch "serial: mxs-auart: fix the wrong RTS hardware flow control" the
mainline mxs-uart driver now sets RTSEN only when hardware flow control is
enabled via software. It is not possible any longer to set RTS manually via
software. However, the manual modification is a valid operation.
Regain the possibility to set RTS via software and only set RTSEN when hardware
flow control is explicitly enabled via settermios cflag CRTSCTS.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
 drivers/tty/serial/mxs-auart.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 6db23b0..21d9b12 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -412,10 +412,12 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)
 
 	u32 ctrl = readl(u->membase + AUART_CTRL2);
 
-	ctrl &= ~AUART_CTRL2_RTSEN;
+	ctrl &= ~(AUART_CTRL2_RTSEN | AUART_CTRL2_RTS);
 	if (mctrl & TIOCM_RTS) {
 		if (tty_port_cts_enabled(&u->state->port))
 			ctrl |= AUART_CTRL2_RTSEN;
+		else
+			ctrl |= AUART_CTRL2_RTS;
 	}
 
 	s->ctrl = mctrl;
@@ -676,8 +678,10 @@ static void mxs_auart_settermios(struct uart_port *u,
 				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
 				       | AUART_CTRL2_DMAONERR;
 		}
+		u->flags |= ASYNC_CTS_FLOW;
 		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
 	} else {
+		u->flags &= ~ASYNC_CTS_FLOW;
 		ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);
 	}
 
-- 
1.7.10.4

[PATCH v2] mxs: uart: allow setting RTS from software

[Huang Shijie]

? 2012?12?13? 16:42, Steffen Trumtrar ??:
> With the patch "serial: mxs-auart: fix the wrong RTS hardware flow control" the
> mainline mxs-uart driver now sets RTSEN only when hardware flow control is
> enabled via software. It is not possible any longer to set RTS manually via
> software. However, the manual modification is a valid operation.
> Regain the possibility to set RTS via software and only set RTSEN when hardware
> flow control is explicitly enabled via settermios cflag CRTSCTS.
>
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> ---
>  drivers/tty/serial/mxs-auart.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index 6db23b0..21d9b12 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -412,10 +412,12 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)
>  
>  	u32 ctrl = readl(u->membase + AUART_CTRL2);
>  
> -	ctrl &= ~AUART_CTRL2_RTSEN;
> +	ctrl &= ~(AUART_CTRL2_RTSEN | AUART_CTRL2_RTS);
>  	if (mctrl & TIOCM_RTS) {
>  		if (tty_port_cts_enabled(&u->state->port))
>  			ctrl |= AUART_CTRL2_RTSEN;
> +		else
> +			ctrl |= AUART_CTRL2_RTS;
>  	}
>  
>  	s->ctrl = mctrl;
> @@ -676,8 +678,10 @@ static void mxs_auart_settermios(struct uart_port *u,
>  				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
>  				       | AUART_CTRL2_DMAONERR;
>  		}
> +		u->flags |= ASYNC_CTS_FLOW;
>  		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
>  	} else {
> +		u->flags &= ~ASYNC_CTS_FLOW;
I think these two lines is not needed.
uart_change_speed() has set/unset ASYNC_CTS_FLOW for us.

thanks
Huang Shijie
>  		ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);
>  	}
>  

[PATCH v2] mxs: uart: allow setting RTS from software

[Steffen Trumtrar]

On Thu, Dec 13, 2012 at 06:19:32PM +0800, Huang Shijie wrote:
> ? 2012?12?13? 16:42, Steffen Trumtrar ??:
> > With the patch "serial: mxs-auart: fix the wrong RTS hardware flow control" the
> > mainline mxs-uart driver now sets RTSEN only when hardware flow control is
> > enabled via software. It is not possible any longer to set RTS manually via
> > software. However, the manual modification is a valid operation.
> > Regain the possibility to set RTS via software and only set RTSEN when hardware
> > flow control is explicitly enabled via settermios cflag CRTSCTS.
> >
> > Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> > ---
> >  drivers/tty/serial/mxs-auart.c |    6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> > index 6db23b0..21d9b12 100644
> > --- a/drivers/tty/serial/mxs-auart.c
> > +++ b/drivers/tty/serial/mxs-auart.c
> > @@ -412,10 +412,12 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)
> >  
> >  	u32 ctrl = readl(u->membase + AUART_CTRL2);
> >  
> > -	ctrl &= ~AUART_CTRL2_RTSEN;
> > +	ctrl &= ~(AUART_CTRL2_RTSEN | AUART_CTRL2_RTS);
> >  	if (mctrl & TIOCM_RTS) {
> >  		if (tty_port_cts_enabled(&u->state->port))
> >  			ctrl |= AUART_CTRL2_RTSEN;
> > +		else
> > +			ctrl |= AUART_CTRL2_RTS;
> >  	}
> >  
> >  	s->ctrl = mctrl;
> > @@ -676,8 +678,10 @@ static void mxs_auart_settermios(struct uart_port *u,
> >  				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
> >  				       | AUART_CTRL2_DMAONERR;
> >  		}
> > +		u->flags |= ASYNC_CTS_FLOW;
> >  		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
> >  	} else {
> > +		u->flags &= ~ASYNC_CTS_FLOW;
> I think these two lines is not needed.
> uart_change_speed() has set/unset ASYNC_CTS_FLOW for us.

I don't know that much of the inner workings of the serial framework, but it
seems like it is guaranteed, that uart_change_speed is called before the
mxs_auart_settermios. And therefore you are right and the two lines can be
dropped.

Regards,
Steffen

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