Kernel 4.1 ( no cap ) & RS485


I’m trying to make rs485 working on the kernel 4.1 :

&uart1 {
pinctrl-names = “default”;
pinctrl-0 = <&uart1_pins>;
status = “okay”;
rts-gpio = <&gpio0 27 GPIO_ACTIVE_HIGH>;
rs485-rts-delay = <1 1>;

but in the boot log I have :

[ 2.961866] 48022000.serial: ttyS1 at MMIO 0x48022000 (irq = 155, base_baud = 3000000) is a 8250

does it mean that it’s the driver 8250 that handle this uart ?

If it’s the case, that not good, because only the driver omap handle rs485.

When I’m trying to configure the RS485 port, I have the errno = 25 = Not a typewriter


switch back to the old omap_serial.c driver

The new omap_8250 still needs to be extended to rs485..


8250 is the uart type its a serial device

rs485 denotes a differential serial hardware layer

you still need the 8250 driver to talk serial

btw see this thread:

Since you've done a lot with rs485 i think you can help extend
omap_8250 for rs485.. (the 8250 already has rs485 support, and with
the mctrl_gpio helpers it should be easy-ish..)


looks like infradead dropped the last message:


Yes, that’s a good idea, I will look into the driver 8250 soon.