linux-kernel - Re: [PATCH v7 2/6] serial: 8250: create lsr_save

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Date:   Wed, 15 Jun 2022 17:01:32 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     linux-serial@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-kernel@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Lino Sanfilippo <LinoSanfilippo@....de>
Subject: Re: [PATCH v7 2/6] serial: 8250: create lsr_save_mask

On Wed, Jun 15, 2022 at 03:48:25PM +0300, Ilpo Järvinen wrote:
> Allow drivers to alter LSR save mask.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> ---
>  drivers/tty/serial/8250/8250.h      | 2 +-
>  drivers/tty/serial/8250/8250_core.c | 4 ++++
>  drivers/tty/serial/8250/8250_dw.c   | 2 +-
>  include/linux/serial_8250.h         | 1 +
>  4 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
> index 0ff5688ba90c..5cc967fe3b59 100644
> --- a/drivers/tty/serial/8250/8250.h
> +++ b/drivers/tty/serial/8250/8250.h
> @@ -138,7 +138,7 @@ static inline u16 serial_lsr_in(struct uart_8250_port *up)
>  	u16 lsr = up->lsr_saved_flags;
>  
>  	lsr |= serial_in(up, UART_LSR);
> -	up->lsr_saved_flags = lsr & LSR_SAVE_FLAGS;
> +	up->lsr_saved_flags = lsr & up->lsr_save_mask;
>  
>  	return lsr;
>  }
> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
> index 90ddc8924811..57e86133af4f 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -1007,6 +1007,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
>  		uart->port.rs485	= up->port.rs485;
>  		uart->rs485_start_tx	= up->rs485_start_tx;
>  		uart->rs485_stop_tx	= up->rs485_stop_tx;
> +		uart->lsr_save_mask	= up->lsr_save_mask;
>  		uart->dma		= up->dma;
>  
>  		/* Take tx_loadsz from fifosize if it wasn't set separately */
> @@ -1094,6 +1095,9 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
>  			ret = 0;
>  		}
>  
> +		if (!uart->lsr_save_mask)
> +			uart->lsr_save_mask = LSR_SAVE_FLAGS;	/* Use default LSR mask */
> +
>  		/* Initialise interrupt backoff work if required */
>  		if (up->overrun_backoff_time_ms > 0) {
>  			uart->overrun_backoff_time_ms =
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index 4cc69bb612ab..167a691c7b19 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -129,7 +129,7 @@ static void dw8250_tx_wait_empty(struct uart_port *p)
>  
>  	while (tries--) {
>  		lsr = readb (p->membase + (UART_LSR << p->regshift));
> -		up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
> +		up->lsr_saved_flags |= lsr & up->lsr_save_mask;
>  
>  		if (lsr & UART_LSR_TEMT)
>  			break;
> diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
> index 4565f25ba9a2..8c7b793aa4d7 100644
> --- a/include/linux/serial_8250.h
> +++ b/include/linux/serial_8250.h
> @@ -120,6 +120,7 @@ struct uart_8250_port {
>  	 */
>  #define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
>  	u16			lsr_saved_flags;
> +	u16			lsr_save_mask;
>  #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
>  	unsigned char		msr_saved_flags;
>  
> -- 
> 2.30.2
> 

-- 
With Best Regards,
Andy Shevchenko