1a613626d2
On a board that needs to drive RTS GPIO high in order to enable the
transmission of 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";
};
and userspace configures the uart port as follows:
/* enable RS485 mode: */
rs485conf.flags |= SER_RS485_ENABLED;
/* set logical level for RTS pin equal to 1 when sending: */
rs485conf.flags |= SER_RS485_RTS_ON_SEND;
/* set logical level for RTS pin equal to 0 after sending: */
rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
However the RTS GPIO polarity observed in the oscilloscope is inverted.
When the SER_RS485_RTS_ON_SEND flag is set the imx_port_rts_active()
function should be called and following the same logic when
SER_RS485_RTS_AFTER_SEND flag is cleared the imx_port_rts_inactive()
should be called.
Do such logic change so that RS485 communication in half duplex can
work successfully when the RTS GPIO pin is passed via device tree.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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