linux-kernel - Re: [PATCH] tty: serial: meson: if no alias specified use an available id

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Date:   Tue, 15 Jan 2019 10:35:25 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Loys Ollivier <lollivier@...libre.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Kevin Hilman <khilman@...libre.com>
Cc:     linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty: serial: meson: if no alias specified use an
 available id

On 14/01/2019 17:54, Loys Ollivier wrote:
> At probe, the uart driver tries to get an id from a device tree alias.
> When no alias was specified, the driver would return an error and probing
> would fail.
> 
> Providing an alias for registering a serial device should not be mandatory.
> If the device tree does not specify an alias, provide an id from a reserved
> range so that the probing can continue.
> 
> Signed-off-by: Loys Ollivier <lollivier@...libre.com>
> ---
>  drivers/tty/serial/meson_uart.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
> index 8a842591b37c..fbc5bc022a39 100644
> --- a/drivers/tty/serial/meson_uart.c
> +++ b/drivers/tty/serial/meson_uart.c
> @@ -72,7 +72,8 @@
>  #define AML_UART_BAUD_USE		BIT(23)
>  #define AML_UART_BAUD_XTAL		BIT(24)
>  
> -#define AML_UART_PORT_NUM		6
> +#define AML_UART_PORT_NUM		12
> +#define AML_UART_PORT_OFFSET		6
>  #define AML_UART_DEV_NAME		"ttyAML"
>  
>  
> @@ -654,10 +655,20 @@ static int meson_uart_probe(struct platform_device *pdev)
>  	struct resource *res_mem, *res_irq;
>  	struct uart_port *port;
>  	int ret = 0;
> +	int id = -1;
>  
>  	if (pdev->dev.of_node)
>  		pdev->id = of_alias_get_id(pdev->dev.of_node, "serial");
>  
> +	if (pdev->id < 0) {
> +		for (id = AML_UART_PORT_OFFSET; id < AML_UART_PORT_NUM; id++) {
> +			if (!meson_ports[id]) {
> +				pdev->id = id;
> +				break;
> +			}
> +		}
> +	}
> +
>  	if (pdev->id < 0 || pdev->id >= AML_UART_PORT_NUM)
>  		return -EINVAL;
>  
> 

This is welcome !

You could also add:
Suggested-by: Rob Herring <robh@...nel.org>

Reviewed-by: Neil Armstrong <narmstrong@...libre.com>

Neil