RS485, DE after one time sending stays high

[jhi]

Next problem with my board is the RS485. I can send bytes, but can't receive because after sending once the DE stays always high. Without sending receive of course works.

&uart5 {
	status = "okay";
    pinctrl-names = "default", "sleep","idle";
    pinctrl-0 = <&uart5_pins_a>;
    pinctrl-1 = <&uart5_sleep_pins_a>;
	pinctrl-2 = <&uart5_idle_pins_a>;
 
	rts-gpios = <&gpioc 6 GPIO_ACTIVE_HIGH>;
	rs485-rts-delay = <0 0>;
	linux,rs485-enabled-at-boot-time;
};

uart5_pins_a: uart5-0 {
                                pins1 {
                                        pinmux = <STM32_PINMUX('B', 6, AF12)>; /* UART5_TX */
                                        bias-disable;
                                        drive-push-pull;
                                        slew-rate = <0>;
                                };
                                pins2 {
                                        pinmux = <STM32_PINMUX('B', 5, AF12)>; /* UART5_RX */
                                        bias-pull-up;
                                };
                        };
 
                        uart5_idle_pins_a: uart5-idle-0 {
                                pins1 {
                                        pinmux = <STM32_PINMUX('B', 6, ANALOG)>; /* UART5_TX */
                                };
                                pins2 {
                                        pinmux = <STM32_PINMUX('B', 5, AF8)>; /* UART5_RX */
                                        bias-pull-up;
                                };
                        };
 
                        uart5_sleep_pins_a: uart5-sleep-0 {
                                pins {
                                        pinmux = <STM32_PINMUX('B', 6, ANALOG)>, /* UART5_TX */
                                                 <STM32_PINMUX('B', 5, ANALOG)>; /* UART5_RX */
                                };
                        };

I also tried setting these with ioctl but the result is always the same. What am I doing wrong?

[jhi]

Could some one help me with this @Community member​  @Gregory PLANCHON​ ?

I'm using kernel 5.10.

[jhi]

The moment I open the port (open( /dev/ttySTM2, O_RDWR | O_NOCTTY | O_NONBLOCK ) the control signal goes high and stays high.

I also tried with rs485-rts-active-low;, but then the signal will stay low and can't send anything. I also back ported the stm32-usart.c from 5.15 but it didn't make any difference. For me it seems that it is stuck in sending mode, but why?

And why is the flag SER_RS485_RX_DURING_TX always set on? It also didn't work if I commented it out.

[jhi]

I tried the uart7 where I have possibility to use hardware control pin and it works. So it seems that the RTS control is just broken in your driver if using other pins. @Community member​ @Gregory PLANCHON​ Any plans on fixing this?