On Fri, Sep 15, 2017 at 02:56:35PM +0200, Clemens Gruber wrote:
> On Thu, Sep 14, 2017 at 01:11:33PM +0100, Ian Jamison wrote:
> > UART core function uart_update_mctrl relies on a cached value of
> > modem control lines. This was used but not updated by local RTS
> > control functions within imx.c. These are used for RS485 line
> > driver enable signalling. Having an out-of-date value in the cached
> > mctrl can result in the transmitter being enabled when it shouldn't
> > be.
> >
> > Fix this by updating the mctrl value before applying it.
> >
> > Cc: Uwe-Kleine König <u.kleine-koenig@xxxxxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
> > Cc: Fabio Estevam <festevam@xxxxxxxxx>
> > Cc: Fabio Estevam <fabio.estevam@xxxxxxx>
> > Signed-off-by: Ian Jamison <ian.dev@xxxxxxxxxx>
> > ---
> > Compile tested only, since my devboard uses a monostable off the TXD
> > line to enable the transmitter.
> >
> > Resending to CC Fabio and Clemens.
> >
> > drivers/tty/serial/imx.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> > index dfeff3951f93..3657d745e90f 100644
> > --- a/drivers/tty/serial/imx.c
> > +++ b/drivers/tty/serial/imx.c
> > @@ -334,7 +334,8 @@ static void imx_port_rts_active(struct imx_port *sport, unsigned long *ucr2)
> > {
> > *ucr2 &= ~(UCR2_CTSC | UCR2_CTS);
> >
> > - mctrl_gpio_set(sport->gpios, sport->port.mctrl | TIOCM_RTS);
> > + sport->port.mctrl |= TIOCM_RTS;
> > + mctrl_gpio_set(sport->gpios, sport->port.mctrl);
> > }
> >
> > static void imx_port_rts_inactive(struct imx_port *sport, unsigned long *ucr2)
> > @@ -342,7 +343,8 @@ static void imx_port_rts_inactive(struct imx_port *sport, unsigned long *ucr2)
> > *ucr2 &= ~UCR2_CTSC;
> > *ucr2 |= UCR2_CTS;
> >
> > - mctrl_gpio_set(sport->gpios, sport->port.mctrl & ~TIOCM_RTS);
> > + sport->port.mctrl &= ~TIOCM_RTS;
> > + mctrl_gpio_set(sport->gpios, sport->port.mctrl);
> > }
> >
> > static void imx_port_rts_auto(struct imx_port *sport, unsigned long *ucr2)
> > --
> > 2.14.1
> >
>
> Looks good to me. I tested RS-485 communications with this patch applied
> between an i.MX6Q board and my host PC (with a RS-485-to-232 converter).
>
> Tested-by: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
Did it actually repair someting? Do you use it in combination with my
patch that masked RTS from uart_dtr_rts? Do you use a gpio for RTS or
the native function?
I have this change in my wip state, too, and it improves the situation,
but it's not working compeletely yet.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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