linux-kernel - Re: [PATCH 2/3] serial: 8250_aspeed_vuart: initialize vuart->port in aspeed_vuart

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Message-Id: <6d4338e2-d9be-411a-aeb7-7d46121b73d4@www.fastmail.com>
Date:   Thu, 13 May 2021 11:04:06 +0930
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Zev Weiss" <zev@...ilderbeest.net>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Jeremy Kerr" <jk@...abs.org>
Cc:     openbmc@...ts.ozlabs.org, "Jiri Slaby" <jirislaby@...nel.org>,
        "Joel Stanley" <joel@....id.au>, "Johan Hovold" <johan@...nel.org>,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] serial: 8250_aspeed_vuart: initialize vuart->port in aspeed_vuart_probe()



On Mon, 10 May 2021, at 11:12, Zev Weiss wrote:
> Previously this had only been initialized if we hit the throttling path
> in aspeed_vuart_handle_irq(); moving it to the probe function is a
> slight consistency improvement and avoids redundant reinitialization in
> the interrupt handler.  It also serves as preparation for converting the
> driver's I/O accesses to use port->port.membase instead of its own
> vuart->regs.
> 
> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
> ---
>  drivers/tty/serial/8250/8250_aspeed_vuart.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c 
> b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> index 9e8b2e8e32b6..249164dc397b 100644
> --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
> +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> @@ -349,11 +349,9 @@ static int aspeed_vuart_handle_irq(struct 
> uart_port *port)
>  			struct aspeed_vuart *vuart = port->private_data;
>  			__aspeed_vuart_set_throttle(up, true);
>  
> -			if (!timer_pending(&vuart->unthrottle_timer)) {
> -				vuart->port = up;
> +			if (!timer_pending(&vuart->unthrottle_timer))
>  				mod_timer(&vuart->unthrottle_timer,
>  					  jiffies + unthrottle_timeout);
> -			}
>  
>  		} else {
>  			count = min(space, 256);
> @@ -511,6 +509,7 @@ static int aspeed_vuart_probe(struct platform_device *pdev)
>  		goto err_clk_disable;
>  
>  	vuart->line = rc;
> +	vuart->port = serial8250_get_port(vuart->line);

The documentation of serial8250_get_port() is somewhat concerning wrt 
the use:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tty/serial/8250/8250_core.c?h=v5.13-rc1#n399

However, given the existing behaviour it shouldn't be problematic?

Andrew