linux-kernel - Re: [PATCH v4 2/5] serial/8250: Use the cache value of the FCR register

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Message-ID: <ce8be768-6210-c3b-2131-de302a7757d@linux.intel.com>
Date:   Thu, 17 Mar 2022 10:29:40 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Wander Lairson Costa <wander@...hat.com>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Johan Hovold <johan@...nel.org>,
        "Maciej W. Rozycki" <macro@...am.me.uk>,
        Serge Semin <fancer.lancer@...il.com>,
        Lukas Wunner <lukas@...ner.de>,
        Pali Rohár <pali@...nel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>, rostedt@...dmis.org,
        senozhatsky@...omium.org, andre.goddard@...il.com,
        sudipm.mukherjee@...il.com, andy.shevchenko@...il.com,
        David.Laight@...lab.com, jonathanh@...dia.com, phil@...pberrypi.com
Subject: Re: [PATCH v4 2/5] serial/8250: Use the cache value of the FCR
 register

On Wed, 16 Mar 2022, Wander Lairson Costa wrote:

> commit 5021d709b31b ("tty: serial: Use fifo in 8250 console driver")
> erroneous tries to read the FCR register content, but this register is
> write-only.
> 
> This patch fixes that by reading the content from the port struct fcr
> field.
> 
> Thanks to Jon Hunter and Jiri Slaby.
> 
> Suggested-by: Jiri Slaby <jirislaby@...nel.org>
> Reported-by: Jon Hunter <jonathanh@...dia.com>
> Signed-off-by: Wander Lairson Costa <wander@...hat.com>
> ---
>  drivers/tty/serial/8250/8250_port.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 2abb3de11a48..9f3fa9fe2a4e 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -3410,7 +3410,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
>  
>  	use_fifo = (up->capabilities & UART_CAP_FIFO) &&
>  		port->fifosize > 1 &&
> -		(serial_port_in(port, UART_FCR) & UART_FCR_ENABLE_FIFO) &&
> +		(up->fcr & UART_FCR_ENABLE_FIFO) &&

Didn't you just add this line in 1/5? Please merge this kind of fixes that 
are due to development history of a change to the main patch itself.


-- 
 i.