From: Steffen Trumtrar <s.trumtrar@pengutronix.de>
To: Huang Shijie <b32955@freescale.com>
Cc: linux-serial@vger.kernel.org, stable@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Alan Cox <alan@linux.intel.com>
Subject: Re: [PATCH] mxs: uart: allow setting RTS from software
Date: Thu, 13 Dec 2012 09:40:17 +0100 [thread overview]
Message-ID: <20121213084017.GA27832@pengutronix.de> (raw)
In-Reply-To: <50C93B6B.7090206@freescale.com>
Hi,
On Thu, Dec 13, 2012 at 10:20:27AM +0800, Huang Shijie wrote:
> 于 2012年12月13日 00:31, Steffen Trumtrar 写道:
> > 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
> Is there any user case to set the RTS via software?
> I am confused at this.
there are cases where the RTS is used in a non-standard way. And the always-on
hardware flowcontrol breaks these (e.g. Echelon FT5000).
And as stated in the commit message, it is a valid operation to use software
flow control.
> > flow control is explicitly enabled via settermios cflag CRTSCTS.
> >
> > Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> > ---
> > drivers/tty/serial/mxs-auart.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> > index 6db23b0..9b62c4b 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;
> > @@ -678,6 +680,10 @@ static void mxs_auart_settermios(struct uart_port *u,
> > }
> > ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
> > } else {
> > + u->flags |= ASYNC_CTS_FLOW;
> > + ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
> > + } else {
> > + u->flags &= ~ASYNC_CTS_FLOW;
> bug.
>
> Your code adds TWO "else" here.
>
Oops, wrong merge resolution. Will fix that.
Regards,
Steffen
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
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WARNING: multiple messages have this Message-ID (diff)
From: s.trumtrar@pengutronix.de (Steffen Trumtrar)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] mxs: uart: allow setting RTS from software
Date: Thu, 13 Dec 2012 09:40:17 +0100 [thread overview]
Message-ID: <20121213084017.GA27832@pengutronix.de> (raw)
In-Reply-To: <50C93B6B.7090206@freescale.com>
Hi,
On Thu, Dec 13, 2012 at 10:20:27AM +0800, Huang Shijie wrote:
> ? 2012?12?13? 00:31, 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
> Is there any user case to set the RTS via software?
> I am confused at this.
there are cases where the RTS is used in a non-standard way. And the always-on
hardware flowcontrol breaks these (e.g. Echelon FT5000).
And as stated in the commit message, it is a valid operation to use software
flow control.
> > flow control is explicitly enabled via settermios cflag CRTSCTS.
> >
> > Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> > ---
> > drivers/tty/serial/mxs-auart.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> > index 6db23b0..9b62c4b 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;
> > @@ -678,6 +680,10 @@ static void mxs_auart_settermios(struct uart_port *u,
> > }
> > ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
> > } else {
> > + u->flags |= ASYNC_CTS_FLOW;
> > + ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
> > + } else {
> > + u->flags &= ~ASYNC_CTS_FLOW;
> bug.
>
> Your code adds TWO "else" here.
>
Oops, wrong merge resolution. Will fix that.
Regards,
Steffen
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
next prev parent reply other threads:[~2012-12-13 8:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-12 16:31 [PATCH] mxs: uart: allow setting RTS from software Steffen Trumtrar
2012-12-12 16:31 ` Steffen Trumtrar
2012-12-13 2:20 ` Huang Shijie
2012-12-13 2:20 ` Huang Shijie
2012-12-13 8:40 ` Steffen Trumtrar [this message]
2012-12-13 8:40 ` Steffen Trumtrar
2012-12-14 14:11 ` Ben Hutchings
2012-12-14 14:11 ` Ben Hutchings
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