On Sat, Jan 07, 2017 at 07:38:31PM -0200, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@xxxxxxx>
>
> On a board that needs to drive RTS GPIO high in order to enable the
> transmissionof a RS485 transceiver the following description is passed
> in the devide tree:
>
> &uart4 {
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_uart4>;
> rts-gpios = <&gpio6 2 GPIO_ACTIVE_HIGH>;
> status = "okay";
> };
>
> However the polarity observed on the oscilloscope is inverted.
>
> Change the mctrl_gpio_set() logic so that the RTS gpio pin can
> behave correctly.
>
> Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxx>
> ---
> Hi,
>
> Marking as RFC as I don't know if this is the proper way to fix it.
>
> Is my device tree description correct assuming I need RTS pin going to
> high to enable the TXEN pin of the RS485 transceiver?
>
> Thanks
>
> drivers/tty/serial/imx.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 33fcc84..451e50f 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -339,14 +339,14 @@ static void imx_port_rts_active(struct imx_port *sport, unsigned long *ucr2)
> *ucr2 &= ~UCR2_CTSC;
> *ucr2 |= UCR2_CTS;
>
> - mctrl_gpio_set(sport->gpios, sport->port.mctrl | TIOCM_RTS);
> + mctrl_gpio_set(sport->gpios, sport->port.mctrl & ~TIOCM_RTS);
> }
>
> static void imx_port_rts_inactive(struct imx_port *sport, unsigned long *ucr2)
> {
> *ucr2 &= ~(UCR2_CTSC | UCR2_CTS);
>
> - mctrl_gpio_set(sport->gpios, sport->port.mctrl & ~TIOCM_RTS);
> + mctrl_gpio_set(sport->gpios, sport->port.mctrl | TIOCM_RTS);
> }
>
> static void imx_port_rts_auto(struct imx_port *sport, unsigned long *ucr2)
> --
> 2.7.4
>
Tested-by: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
Regards,
Clemens
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