linux-kernel - Re: [PATCH 10/33] serial: 8250: invert conditions in RSA functions

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Message-ID: <19c8369c-6839-1876-eefe-33dd69977707@linux.intel.com>
Date: Wed, 11 Jun 2025 14:45:54 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
cc: gregkh@...uxfoundation.org, linux-serial@...r.kernel.org, 
    linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/33] serial: 8250: invert conditions in RSA functions

On Wed, 11 Jun 2025, Jiri Slaby (SUSE) wrote:

> The code can short-return in case something does not hold. So invert the
> conditions and return in those cases immediately. This makes the code
> flow more natural and less nested.

Ah, never mind my comment on the previous patch :-).

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

-- 
 i.


> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
> ---
>  drivers/tty/serial/8250/8250_port.c | 59 +++++++++++++++++------------
>  1 file changed, 34 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 233316a88df2..e7652d62ab2f 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -743,15 +743,16 @@ static int __enable_rsa(struct uart_8250_port *up)
>   */
>  static void enable_rsa(struct uart_8250_port *up)
>  {
> -	if (up->port.type == PORT_RSA) {
> -		if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) {
> -			uart_port_lock_irq(&up->port);
> -			__enable_rsa(up);
> -			uart_port_unlock_irq(&up->port);
> -		}
> -		if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16)
> -			serial_out(up, UART_RSA_FRR, 0);
> +	if (up->port.type != PORT_RSA)
> +		return;
> +
> +	if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) {
> +		uart_port_lock_irq(&up->port);
> +		__enable_rsa(up);
> +		uart_port_unlock_irq(&up->port);
>  	}
> +	if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16)
> +		serial_out(up, UART_RSA_FRR, 0);
>  }
>  
>  /*
> @@ -764,37 +765,45 @@ static void disable_rsa(struct uart_8250_port *up)
>  	unsigned char mode;
>  	int result;
>  
> -	if (up->port.type == PORT_RSA &&
> -	    up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16) {
> -		uart_port_lock_irq(&up->port);
> +	if (up->port.type != PORT_RSA)
> +		return;
>  
> -		mode = serial_in(up, UART_RSA_MSR);
> -		result = !(mode & UART_RSA_MSR_FIFO);
> +	if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16)
> +		return;
>  
> -		if (!result) {
> -			serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
> -			mode = serial_in(up, UART_RSA_MSR);
> -			result = !(mode & UART_RSA_MSR_FIFO);
> -		}
> +	uart_port_lock_irq(&up->port);
> +	mode = serial_in(up, UART_RSA_MSR);
> +	result = !(mode & UART_RSA_MSR_FIFO);
>  
> -		if (result)
> -			up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16;
> -		uart_port_unlock_irq(&up->port);
> +	if (!result) {
> +		serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
> +		mode = serial_in(up, UART_RSA_MSR);
> +		result = !(mode & UART_RSA_MSR_FIFO);
>  	}
> +
> +	if (result)
> +		up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16;
> +	uart_port_unlock_irq(&up->port);
>  }
>  
>  static void rsa_autoconfig(struct uart_8250_port *up)
>  {
>  	/* Only probe for RSA ports if we got the region. */
> -	if (up->port.type == PORT_16550A && up->probe & UART_PROBE_RSA &&
> -	    __enable_rsa(up))
> +	if (up->port.type != PORT_16550A)
> +		return;
> +	if (!(up->probe & UART_PROBE_RSA))
> +		return;
> +
> +	if (__enable_rsa(up))
>  		up->port.type = PORT_RSA;
>  }
>  
>  static void rsa_reset(struct uart_8250_port *up)
>  {
> -	if (up->port.type == PORT_RSA)
> -		serial_out(up, UART_RSA_FRR, 0);
> +	if (up->port.type != PORT_RSA)
> +		return;
> +
> +	serial_out(up, UART_RSA_FRR, 0);
>  }
>  #else
>  static inline void enable_rsa(struct uart_8250_port *up) {}
>