Re: [PATCH v2 1/3] serial: 8250: allow use of non-runtime configured uart ports

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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On Tue, 18 Oct 2022, Martin Hundebøll wrote:

> The logic to find unused ports when registering new 8250 uart ports
> searches only up to CONFIG_SERIAL_8250_RUNTIME_UARTS, which forces users
> of external 8250 ports to increase the number of runtime ports
> artificially.
> 
> Fix this by initializing each allocated port structure with basic
> settings like line number and uart operation callbacks, and by searching
> the entire array of allocated ports to find an unused one.

So nr_uarts no longer means "Maximum number of UARTs supported." ?
Perhaps it should be reworded too.

-- 
 i.
 
> Signed-off-by: Martin Hundebøll <martin@geanix.com>
> ---
>  drivers/tty/serial/8250/8250_core.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
> index 94fbf0add2ce..a166cc66e7d1 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -500,7 +500,7 @@ static void __init serial8250_isa_init_ports(void)
>  	if (nr_uarts > UART_NR)
>  		nr_uarts = UART_NR;
>  
> -	for (i = 0; i < nr_uarts; i++) {
> +	for (i = 0; i < UART_NR; i++) {
>  		struct uart_8250_port *up = &serial8250_ports[i];
>  		struct uart_port *port = &up->port;
>  
> @@ -926,15 +926,16 @@ static struct uart_8250_port *serial8250_find_match_or_unused(const struct uart_
>  
>  	/* try line number first if still available */
>  	i = port->line;
> -	if (i < nr_uarts && serial8250_ports[i].port.type == PORT_UNKNOWN &&
> +	if (i < UART_NR && serial8250_ports[i].port.type == PORT_UNKNOWN &&
>  			serial8250_ports[i].port.iobase == 0)
>  		return &serial8250_ports[i];
> +
>  	/*
>  	 * We didn't find a matching entry, so look for the first
>  	 * free entry.  We look for one which hasn't been previously
>  	 * used (indicated by zero iobase).
>  	 */
> -	for (i = 0; i < nr_uarts; i++)
> +	for (i = 0; i < UART_NR; i++)
>  		if (serial8250_ports[i].port.type == PORT_UNKNOWN &&
>  		    serial8250_ports[i].port.iobase == 0)
>  			return &serial8250_ports[i];
> @@ -943,7 +944,7 @@ static struct uart_8250_port *serial8250_find_match_or_unused(const struct uart_
>  	 * That also failed.  Last resort is to find any entry which
>  	 * doesn't have a real port associated with it.
>  	 */
> -	for (i = 0; i < nr_uarts; i++)
> +	for (i = 0; i < UART_NR; i++)
>  		if (serial8250_ports[i].port.type == PORT_UNKNOWN)
>  			return &serial8250_ports[i];
>  
>