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 Having an out-of-date value in the cached 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/ | -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html