Re: [PATCH DON'T APPLY v2 3/7] serial: 8250: Support rs485 bus termination GPIO

[Andy Shevchenko]

On Thu, Mar 26, 2020 at 12:14:18AM +0100, Heiko Stuebner wrote:
> From: Lukas Wunner <lukas@xxxxxxxxx>
> 
> Amend the serial core to retrieve the rs485 bus termination GPIO from
> the device tree (or ACPI table) and amend the default ->rs485_config()
> callback for 8250 drivers to change the GPIO on request from user space.

> +	port->rs485_term_gpio = devm_gpiod_get(dev, "rs485-term",
> +					       GPIOD_FLAGS_BIT_DIR_OUT);
> +	if (IS_ERR(port->rs485_term_gpio)) {
> +		ret = PTR_ERR(port->rs485_term_gpio);
> +		port->rs485_term_gpio = NULL;
> +		if (ret != -ENOENT) {
> +			if (ret != -EPROBE_DEFER)
> +				dev_err(dev, "Cannot get rs485-term-gpios\n");
> +			return ret;
> +		}

NIH of gpiod_get_optional().

> +	} else {
> +		ret = gpiod_get_value(port->rs485_term_gpio);
> +		if (ret < 0) {
> +			dev_err(dev, "Cannot get rs485-term-gpios value\n");
> +			return ret;
> +		}
> +		if (ret)
> +			rs485conf->flags |= SER_RS485_TERMINATE_BUS;
> +	}

-- 
With Best Regards,
Andy Shevchenko