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SubjectRe: [PATCH v8 3/3] tty: 8250_omap: Use software emulated RS485 direction control
From
Hello,

2016-02-01 21:09 GMT+03:00 "Matwey V. Kornilov" <matwey@sai.msu.ru>:
> +static int omap_8250_rs485_config(struct uart_port *port,
> + struct serial_rs485 *rs485)
> +{
> + struct uart_8250_port *up = up_to_u8250p(port);
> +
> + /* Clamp the delays to [0, 100ms] */
> + rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
> + rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
> +
> + port->rs485 = *rs485;
> +
> + /*
> + * Both serial8250_em485_init and serial8250_em485_destroy
> + * are idempotent
> + */
> + if (rs485->flags & SER_RS485_ENABLED) {
> + int ret = serial8250_em485_init(up);
> +
> + if (ret) {
> + rs485->flags &= ~SER_RS485_ENABLED;
> + port->rs485.flags &= ~SER_RS485_ENABLED;
> + }
> + return ret;
> + }
> +
> + serial8250_em485_destroy(up);
> +
> + return 0;
> +}

I think that an invocation of serial8250_em485_destroy() should be
performed inside omap8250_remove() as well. However there is a catch -
serial8250_get_port() is only reserved for suspend-resume power
management operations, and I am aware of no other means how to supply
an uart_8250_port to serial8250_em485_destroy() at that point.

Similarly, I got no idea on how to implement handling
"linux,rs485-enabled-at-boot-time" property without using
serial8250_get_port() directly (well, honestly I could try invoking
the corresponding ioctl somehow, but that's gonna be plain ugly at
least).

Regards,
Ilyas G.

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