linux-kernel - Re: [PATCH 09/33] serial: 8250: remove CONFIG_SERIAL_8250

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Message-ID: <95e65501-7096-045f-db52-26e90683a003@linux.intel.com>
Date: Wed, 11 Jun 2025 14:42:05 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
    linux-serial <linux-serial@...r.kernel.org>, 
    LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 09/33] serial: 8250: remove CONFIG_SERIAL_8250_RSA inline
 macros from code

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

> All these:
>   #ifdef CONFIG_SERIAL_8250_RSA
>   ...
>   #endif
> 
> in the 8250 generic code distract the reader. Introduce empty inlines to
> handle the !CONFIG_SERIAL_8250_RSA case and handle the '#if's around the
> RSA functions definitions.
> 
> This means rsa_autoconfig() and rsa_reset() functions were introduced to
> contain the particular code.
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
> ---
>  drivers/tty/serial/8250/8250_port.c | 54 ++++++++++++++---------------
>  1 file changed, 27 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index f5407832e8a7..233316a88df2 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -738,6 +738,9 @@ static int __enable_rsa(struct uart_8250_port *up)
>  	return result;
>  }
>  
> +/*
> + * If this is an RSA port, see if we can kick it up to the higher speed clock.
> + */
>  static void enable_rsa(struct uart_8250_port *up)
>  {
>  	if (up->port.type == PORT_RSA) {

In general, a good change but it would also be nice to reverse all these 
type check because then it would be immediately obvious the function does 
nothing if it's not PORT_RSA.

> @@ -752,10 +755,9 @@ static void enable_rsa(struct uart_8250_port *up)
>  }
>  
>  /*
> - * Attempts to turn off the RSA FIFO.  Returns zero on failure.
> - * It is unknown why interrupts were disabled in here.  However,
> - * the caller is expected to preserve this behaviour by grabbing
> - * the spinlock before calling this function.
> + * Attempts to turn off the RSA FIFO and resets the RSA board back to 115kbps compat mode. It is
> + * unknown why interrupts were disabled in here. However, the caller is expected to preserve this
> + * behaviour by grabbing the spinlock before calling this function.
>   */
>  static void disable_rsa(struct uart_8250_port *up)
>  {
> @@ -780,6 +782,25 @@ static void disable_rsa(struct uart_8250_port *up)
>  		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))
> +		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);
> +}
> +#else
> +static inline void enable_rsa(struct uart_8250_port *up) {}
> +static inline void disable_rsa(struct uart_8250_port *up) {}
> +static inline void rsa_autoconfig(struct uart_8250_port *up) {}
> +static inline void rsa_reset(struct uart_8250_port *up) {}
>  #endif /* CONFIG_SERIAL_8250_RSA */
>  
>  /*
> @@ -1267,14 +1288,7 @@ static void autoconfig(struct uart_8250_port *up)
>  		break;
>  	}
>  
> -#ifdef CONFIG_SERIAL_8250_RSA
> -	/*
> -	 * Only probe for RSA ports if we got the region.
> -	 */
> -	if (port->type == PORT_16550A && up->probe & UART_PROBE_RSA &&
> -	    __enable_rsa(up))
> -		port->type = PORT_RSA;
> -#endif
> +	rsa_autoconfig(up);
>  
>  	serial_out(up, UART_LCR, save_lcr);
>  
> @@ -1289,10 +1303,7 @@ static void autoconfig(struct uart_8250_port *up)
>  	/*
>  	 * Reset the UART.
>  	 */
> -#ifdef CONFIG_SERIAL_8250_RSA
> -	if (port->type == PORT_RSA)
> -		serial_out(up, UART_RSA_FRR, 0);
> -#endif
> +	rsa_reset(up);
>  	serial8250_out_MCR(up, save_mcr);
>  	serial8250_clear_fifos(up);
>  	serial_in(up, UART_RX);
> @@ -2248,13 +2259,7 @@ int serial8250_do_startup(struct uart_port *port)
>  				UART_DA830_PWREMU_MGMT_FREE);
>  	}
>  
> -#ifdef CONFIG_SERIAL_8250_RSA
> -	/*
> -	 * If this is an RSA port, see if we can kick it up to the
> -	 * higher speed clock.
> -	 */
>  	enable_rsa(up);
> -#endif
>  
>  	/*
>  	 * Clear the FIFO buffers and disable them.
> @@ -2521,12 +2526,7 @@ void serial8250_do_shutdown(struct uart_port *port)
>  			serial_port_in(port, UART_LCR) & ~UART_LCR_SBC);
>  	serial8250_clear_fifos(up);
>  
> -#ifdef CONFIG_SERIAL_8250_RSA
> -	/*
> -	 * Reset the RSA board back to 115kbps compat mode.
> -	 */
>  	disable_rsa(up);
> -#endif
>  
>  	/*
>  	 * Read data port to reset things, and then unlink from
> 

-- 
 i.